Nanotechnology Insights e-Zine

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NANOTECHNOLOGY

INSIGHTS

INTRODUCTION

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In recent years there has been ever increasing activity and interest within the scientific and engineering fields about engineered nanoparticles (ENP). PerkinElmer’s analytical instruments enable engineers and scientists to measure, characterize, and better understand nanomaterials for industrial and academic nanotechnology research. In this Nanotechnology Insights e-Zine you will find a wide range of solutions and scientific papers about nanomaterial applications (from synthesizing to end use) that illustrate PerkinElmer’s support and contribution to customers working in this revolutionary science.

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CONTENTS

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• Frequently Asked Questions- Nanotechnology and Engineered Nanomaterials

• Nanopharmaceuticals and PerkinElmer

Fundamental Concepts

Thermal Analysis

Molecular Spectroscopy

Atomic Spectroscopy

• ImprovedHyperDSCMethodtoDetermineSpecificHeatCapacityofNanocom-positesandProbeforHigh-TemperatureDevitrification

• A Study of Aged Carbon Nanotubes by Thermogravimetirc Analysis

• SimpleMethodofMeasuringtheBandGapEnergyValueofTIO2inthePow-derFormusingaUV/Vis/NIRSpectrometer

• AnalysisofNISTGoldNanoparticlesReferenceMaterialsUsingthe NexION 300 ICP-MS in Single Particle Mode

• ColoradoSchoolofMinesUsesaNexION300QICP-MStoObtainaBetterUnderstanding of the Impact of Engineered Nanomaterials

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Hyphenated Techniques

• CharacterizingInteractionofNanoparticleswithOrganicPollutantsUsingcoupling Thermal Analysis with Spectroscopic Techniques

• An Introduction to Flow Field Flow Fractionation and Coupling to ICP-MS • Coupling Flow Field Flow Fractionation to ICP-MS for the Detection and

Characterization of Silver Nanoparticles

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Fundamental Concepts • Frequently Asked Questions- Nanotechnology and Engineered

Nanomaterials • Nanopharmaceuticals and PerkinElmer

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Frequently asked

questions

Nanotechnology and Engineered Nanomaterials

A Primerauthors:

Andrew W. Salamon, Patrick Courtney and Ian Shuttler

Introduction

In recent years there has been ever increasing activity and excitement within the scientific and engineering communities, driven heavily by government investment, about engineered nanotechnology applications. The U.S. National Science Foundation has estimated that the global nanotechnology market could be worth U.S.$1 trillion by 2015.1 In parallel, much has been written and presented about the excitement and possible dangers of these materials. The tone of these media articles range from how these wonder materials are going to revolutionize all aspects of our lives to how they might kill us! The purpose of this primer is to provide some basic information about engineered nanomaterials so that you will be better informed, understand the new ‘jargon’ and appreciate some of the potential new applications of these materials. In addition, understanding the wide range and types of measurements needed to characterize these nanomaterials along with what solutions PerkinElmer has to support customers working in this field are outlined.

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Table of Contents

What is nanotechnology? 3

What is the market and potential of nanotechnology? 4

What are engineered nanomaterials? 4

Fullerenes, graphene and carbon nanotubes 5

Quantum dots 5

Nanoparticles 6

Nanofibers and Nanowires 6

Where are nanomaterials being used today and in the future? 7

How are nanomaterials characterized? 7

What analytical techniques are used to characterize nanomaterials? 12

What are the environmental implications of nanotechnology? 13

What solutions are provided by PerkinElmer for nanomaterials characterization? 15

Where can I find more information? 16

References 16

Useful books and websites for more information 19

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Q What is nanotechnology?A Nanotechnology is the science and technology of precisely manipulating the struc-

ture of matter at the molecular level. The term nanotechnology embraces many different fields and specialties, including engineering, chemistry, electronics, and medicine, among others, but all are concerned with bringing existing technologies down to a very small scale, measured in nanometers.2 Processes and functionality take place at the nanoscale, exhibiting properties not available in the bulk mate-rial. But what is a nanometer? Figure 1 compares the nano-region to things we know, such as a pin, insect and cells and provides a visual perspective.

Figure 1. Size relationships from large to small to nano.

A nanometer is a thousandth of a micron and a micron is a thousandth of a millimeter, so a nanometer is a millionth of a millimeter or 10-9 meters. To be classified as a nanomaterial (NM), the material must be less than 100 nm in size in at least one direction. According to the International Standards Organization® (ISO) a nano-object is a material with at least one, two or three external dimensions in the nanoscale range of 1 to 100 nm and a nanoparticle is a nano-object with all three external dimensions in the 1 to 100 nm range and showing a property not evident in the bulk material. Hence, a nanofiber, 400 nm long and 12 nm in diameter, and a 20 nm diameter nanoparticle, are both classified as nanomaterials.3

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Even though ISO does not distinguish between engineered nanoparticles and naturally occurring nanoparticles, you should be aware that there are naturally occurring nanoparticles in the aquatic environment such as biodegraded organic matter and colloidal inorganic species and in soils; clays, organic matter and various metal oxides.4 Many important functions of living organisms take place at the nano-scale. The human body uses natural nanoscale materials such as proteins and other molecules, to control the body’s many systems and processes. A typical protein such as hemoglobin, which carries oxygen through the bloodstream, is 5 nm in diameter.5 However, this primer concentrates on Engineered Nanomaterials (ENMs).

Q What is the market and potential of nanotechnology?A

Last year the Russian government announced that it was investing $11 billion in an ambitious plan to develop and commercialize nanotechnologies.7 It is not only gov-ernments that are investing heavily in this area, venture capital firms invested $702M in nanotechnology start-ups in 2007 across 61 investments. The Japanese Mitsubishi Institute projected nanotechnology to be worth U.S.$150 billion on the global market by 2010 and Lux Research® estimated a U.S.$2.6 trillion global market by 2014.1 The U.S. NNI continues to be well funded with a 2010 budget of $1.6B, with total spending since 2001 of nearly $14B. However, to put some of these numbers into perspective, allocation of NNI funds for environmental, health and safety research since 2005 totals $480M.8 In spite of this it is clear that significant investments are being made in all aspects of nanotechnology and that there is considerable potential.

Q What are engineered nanomaterials?A There are many new material terminologies associated with this field. This section

gives a short overview of some of the different types of nanomaterials.

According to the U.S. National Nanotechnology Initiative (NNI), Federal Government funding in the United States, for nanotechnology, has increased from approximately $464 million in 2001 to nearly $1.9 billion for the 2010 fiscal year. Private industry is investing at least as much as the government, according to estimates. The United States is not the only country to recognize the tremendous economic potential of nanotech-nology. While it is difficult to measure accurately, estimates from 2005 showed the European Union (EU) and Japan are investing approximately $1.5 billion and $1.8 billion, respectively, in nanotechnology. Behind them were Korea, China and Taiwan with $300 million, $250 million and $110 million respectively, invested in nanotechnology research and development.6

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Fullerenes, graphene and carbon nanotubes

A Fullerene is any molecule in the form of a hollow sphere, ellipsoid or tubular structure composed entirely of carbon. They are commonly referred to as “Buckyballs” – named after Buckminster Fuller who designed geodesic physical structures and buildings based on this geometry. A Buckyball is a carbon based hollow geometric sphere, first found in soot developed from a laboratory experiment.

It resembles a hollow spherical geodesic dome and is comprised of 60 carbon atoms (C60). Discovered in 1985, it is the roundest and most symmetrical large molecule known to man.9 Fullerenes or Buckyballs are used in nanotechnology. Graphene is a one atom thick planar sheet of carbon atoms densely packed in a honeycomb crystal lattice. Graphene is the basic structural building block of carbon nanotubes and fullerenes. Carbon nanotubes (CNT) also known as ‘buckytubes’ have a cylindrical nanostructure in the form of a tube and an engineered CNT typically has a nanoscale thick wall, geometrically shaped similar to a Buckyball, with a nanoscale diameter, and a length that may exceed 100 nm.

Carbon nanotubes are manufactured as single wall carbon nanotubes (SWCNT) or multiwall car-bon nanotubes (MWCNT). An example is shown in Figure 3. They are synthesized in a variety of ways, including arc discharge, laser ablation and chemical vapor deposition. With respect to tensile strength, carbon nanotubes are the strongest and stiffest materials yet discovered, more than 5 times stronger than Kevlar®. Since CNTs have a very low density, their specific strength is 300 times greater

than stainless steel, though under compression CNTs appear to be a lot weaker.

Quantum dots

Quantum dots, also known as nanocrystals, are another form of nanomaterial and are a specific type of semiconductor. They are 2-10 nanometers (10-50 atoms) in diameter, and because of their electrical characteristics, they are [electrically] tun-able.10 The electrical conductivity of semiconductors can change due to external stimulus such as voltage or exposure to light, etc. As quantum dots have such a

Figure 3. Multiwalled carbon nanotube.

Figure 2. C60 buckyball.

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small size they show different properties to bulk material. Hence the ‘tunability’, for example, sensitivity to different wavelengths of light, can be adjusted by the number of atoms or size of the quantum dot. Quantum dots are typically made from CdSe, ZnS or CdTe compounds, though from a EU Restriction of Hazardous Substances (RoHS) perspective, cadmium-free quantum dots are required.11 For an excellent explanation of quantum dots and their operation in a cadmium selenide semiconductor see the website associated with reference.10

Nanoparticles

Nanoparticles (NP) are synthesized or machined. They range in size from 2 nm to 100 nm. Nanoparticle materials vary depending on their application. Because Nanoparticles are invisible to the naked eye, they are usually supplied suspended in a liquid. This is done for safety and handling reasons. Figure 4 shows gold nanoparticles suspended in liquid. The color is due to the refraction of light the surface area of the particular nanoparticle reflects. Different sized nanoparticles exhibit different colors based on its surface area.12

Figure 4. Suspension of gold nanoparticles.

Figure 5. SEM image of aligned nanofibers. Photo courtesy of Univ. of Wisconsin – Madison, Department of Chemistry.

Nanofibers and Nanowires

Nanofibers are slightly larger in diameter than the typical nanomaterial definition, though still invisible to the naked-eye. Their size ranges between 50 nm - 300 nm in diameter and are generally produced by electro spinning in the case of inor-ganic nanofibers or catalytic synthesis for carbon nanotubes. Figure 5 shows an SEM image of aligned nanofibers. Nanofibers can be electrostatically aligned and biochemically aligned.13,14 Further information about nanofibers fabrication can be found in reference.15 Similar to nanofibers are nanowires, though nanowires are considerably smaller in diameter, of the order of 4 nm and conduct electricity.

In Table 1, the different size characteristics of the various nanomaterials are summarized.

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Table 1. Nanomaterial types and dimension characteristics.

Type of Nanomaterial Number of dimensions and size

Nanoparticle Three dimensions in the 1 to 100 nanometers (nm) range

Nanotubes/nanowires Two dimensions in the 1 to 100 nm range

Nanofibers Length ranges between 50 nm and 300 nm with diameter <50 nm

Nanofilms One dimension in the 1 to 100 nm range

Nanoplates Two dimensions in the 1 to 100 nm range

Q Where are nanomaterials being used today and in the future? A Some of the current applications of many of these nano-related materials and

technology are outlined in Table 2 (Page 8). While this table is not intended to be exhaustive, it does show how wide ranging the applications are. It is clear that the nanomaterial science revolution has the potential and magnitude to be an enormous leap forward in technology. However, it should be noted that there are increasing concerns about the impact of these materials in the environment and their possible impact on human health.

Currently the Woodrow Wilson Center for Scholars through their Project on Emerging Nanotechnologies (PEN) lists in their database, 1015 commercially available nanotechnology containing consumer products in over 20 countries16 up to 2009. This website and searchable database is recommended for those wishing to learn more.

A more comprehensive listing of current and possible future applications of nanomaterials is available on www.PerkinElmer.com/nano

Q How are nanomaterials characterized?A It is important to understand that the excitement regarding the synthesis and

application of nanomaterials is based on the fact that, because of their very small size, the characteristics and behavior are quite different to bulk materials with the same composition. Consequently, the range of parameters that has to be assessed to characterize these materials is large. Fundamentally there are seven key characteristics that contribute to the uniqueness of nanomaterials and these are summarized in Table 3.

In addition to the key seven characteristics, there are two additional qualities that are unique to nanomaterials and important in characterizing them. These are agglomeration, which is the tendency of the particles to clump together and form larger combined particles, and the particle size distribution.

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Table 1. Nanomaterial types and dimension characteristics.

Type of Nanomaterial Number of dimensions and size

Nanoparticle Three dimensions in the 1 to 100 nanometers (nm) range

Nanotubes/nanowires Two dimensions in the 1 to 100 nm range

Nanofibers Length ranges between 50 nm and 300 nm with diameter <50 nm

Nanofilms One dimension in the 1 to 100 nm range

Nanoplates Two dimensions in the 1 to 100 nm range

Q Where are nanomaterials being used today and in the future? A Some of the current applications of many of these nano-related materials and

technology are outlined in Table 2 (Page 8). While this table is not intended to be exhaustive, it does show how wide ranging the applications are. It is clear that the nanomaterial science revolution has the potential and magnitude to be an enormous leap forward in technology. However, it should be noted that there are increasing concerns about the impact of these materials in the environment and their possible impact on human health.

Currently the Woodrow Wilson Center for Scholars through their Project on Emerging Nanotechnologies (PEN) lists in their database, 1015 commercially available nanotechnology containing consumer products in over 20 countries16 up to 2009. This website and searchable database is recommended for those wishing to learn more.

A more comprehensive listing of current and possible future applications of nanomaterials is available on www.PerkinElmer.com/nano

Q How are nanomaterials characterized?A It is important to understand that the excitement regarding the synthesis and

application of nanomaterials is based on the fact that, because of their very small size, the characteristics and behavior are quite different to bulk materials with the same composition. Consequently, the range of parameters that has to be assessed to characterize these materials is large. Fundamentally there are seven key characteristics that contribute to the uniqueness of nanomaterials and these are summarized in Table 3.

In addition to the key seven characteristics, there are two additional qualities that are unique to nanomaterials and important in characterizing them. These are agglomeration, which is the tendency of the particles to clump together and form larger combined particles, and the particle size distribution.

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Table 2. Selection of nanomaterials and usage or application area.

Market Industry Type of Use/Application Area Segment Nanomaterial

Environmental Water Nano zero valent Being tested for the remediation of ground and surface waters iron (nZVI) exposed to chlorinated hydrocarbons17

Gold nanoparticles Various gold nanomaterials are used to enhance imaging properties of a variety of MRI and CT-based contrast agents18

UV absorbing Improved and sustainable water based surface coatings to nanomaterials protect and preserve wood, concrete and metal surfaces used in construction19

Safety and Food Clay Nanomaterials are being used in food packaging. The Security penetration of light, moisture, or gases can alter the sensory characteristics of food products, as well as increase spoilage. Nanomaterials enhance packaging barrier properties20

Energy Pd and V doped Enhance hydrogen fuel cells by increasing storage capacities carbon nanotubes and showing faster hydrogen absorption kinetics21

Medical Various materials Nanomaterials coated with pharmaceutical compounds are being considered as novel inhalation delivery systems for medications difficult to administer by other means22

Textiles/ Silver nanoparticles Integrated with sports clothing to prevent microbial growth, Apparel and odor23,24

Cosmetics/ Nano titanium Used in some cosmetics. The applications include: eye liners, Personal dioxide and nano moisturizers, lipsticks, make-up foundations, soaps, sunscreen, Care Products zinc oxide mascara, and nail polish16

Industrial Defense CNTs Body armor – multilayer-epoxy composites manufactured with CN sheets, the size of a piece of plywood 4’ x 8’ foot, provide a shield that can stop a 9 mm bullet and weighs no more than a pack of playing cards25

Aerospace Clay nanoparticles Incorporated with thermoplastics to create improved fire retardant aircraft interiors26

Automotive 10 nm Cerium oxide Forms part of the Envirox™ diesel fuel catalyst which improves nanoparticles combustion due to the increased surface area of the cerium oxide nanoparticles27

Recreation/ Unknown Holmenkol® AG supply a chemical nanotechnology coating Manu- system under the brand name ‘Nanowax®’ to replace conven- facturing tional ski and snowboard waxes28

Sports CNTs/Yarn High end golf club shafts are made with nano-composites to make equipment the shaft stronger and more flexible. Racing bicycle components29

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Table 3. Nanomaterial characteristics, their impact and importance.

Nanomaterial Characteristic Impact and Importance

Size Key defining criteria for a nanomaterial3 (see Table 1).

Shape Carbon nanosheets with a flat geodesic (hexagonal) structure show improved performance in epoxy composites versus carbon fibers.30

Surface Charge Surface charge is as important as size or shape. Can impact adhesion to surfaces and agglomeration characteristics. Nanoparticles are often coated or ‘capped’ with agents such as polymers (PEG) or surfactants to manage the surface charge issues.

Surface Area This is a critical parameter as the surface area to weight ratio for nanomaterials is huge. For example, one gram of an 8 nm diameter nanoparticle has a surface area of 32 m2. Nanoparticles may have occlusions and cavities on the surface.

Surface Porosity Many nanomaterials are created with zeolite-type porous surfaces. These engineered surfaces are designed for maximum absorption of a specific coating or to accommodate other molecules with a specific size

Composition The chemical composition of nanomaterials is critical to ensure the correct stoichiometry has been achieved. The purity of nanomaterials, impact of different catalysts used in the synthesis and presence of possible contaminants needs to be assessed along with possible coatings that may have been applied.

Structure Knowledge of the structure at the nano level is important. Many nanomaterials are heterogeneous and information concerning crystal structure and grain boundaries is required.

Figure 6. Key parameters to characterize nanomaterials.

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Q What analytical techniques are used to characterize nanomaterials?A As shown in Figure 6 there are seven key characteristics along with agglomeration

and particle size distribution that need to be measured to fully describe a nano-material. Consequently, at the nanoscale, analytical measurement challenges are considerable and the ability to use, for example, one technique such as inductively coupled plasma-mass spectrometry (ICP-MS) to measure the elemental concentration of gold in a suspension of gold nanoparticles as the only metric to assess the material, does not provide all the information needed. To completely characterize the material it is necessary to know a multitude of chemical and physical parameters including; the size of the particles, their shape, surface characteristics, presence of any surface coating and presence of impurities. This small subset illustrates the magnitude of the measurement challenge facing the nanomaterials industry. Table 4 lists the key characteristics and many of the current analytical technologies that can be applied.

In addition to looking at a variety of analytical techniques and their application to nanomaterials it is also important to understand where measurements need to be made, what type of measurements are required and why. To understand this, an overview of the nanomaterial manufacturing process and value chain is necessary. This includes consideration of aspects such as source and quality of raw materials, control of the synthesis/manufacturing process, validation of the final product and subsequent use or incorporation into another product, e.g., a cosmetic preparation. Along this manufacturing chain are a variety of points at which material and hazardous waste may need to be disposed of and there is potential for environmental exposure. Figure 7 provides a high level view of this process in a very fast changing technology area and outlines which characteristics may need to be assessed at the various measurement points. To understand which analytical technologies may be required to provide this information, Figure 7 and Table 4 can be compared. This chain has been developed from recent market research and customer feedback.

Key nanomaterial characteristics require new measurement technologies. An analyti-cal technique that is becoming more prevalent in the nanomaterial field is that of Field Flow Fractionation (FFF) coupled with Light Scattering (LS) and possibly ICP-MS for elemental nanoparticle characterization. Field Flow Fractionation is a separation technique similar to chromatography whereby colloids, macromolecules and nanoparticles are separated by size and should allow a separation of natural and engineered nanomaterials. Further details can be found in a recent review article on the coupling of FFF with ICP-MS31 and the websites under references.32,33

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Figure 7. High-level overview of the engineered nanomaterial manufacturing process and key characteristics.

Electron microscopy is also widely used to characterize nanoparticles. The surface area, porosity, particle shape, and agglomeration can be examined with Scanning Electron Microscopes (SEM), Atomic Force Microscopes (AFM), Tunneling Electron Microscopes (TEM), and Confocal Microscopes.

In the production and characterization of carbon nanotubes (CNTs) the use of Thermogravimetric Analysis (TGA) has found considerable application and can be used to show batch to batch reproducibility, detect changes in the process and validate purification protocols.34 During both the production and formulation process, many nanoparticles are coated or ‘capped’ with a variety of molecules. For assessing the coating, the hyphenated technique of TGA coupled with GC/MS is finding use.35 A critical application in this area is determining the amount of anti-cancer drug that is coated on nanoparticles. This is needed to characterize the dosage being consumed by the patient.

Q What are the environmental implications of nanotechnology?A Process waste has always been a manufacturing issue. It is slightly different today

when nanoparticles are considered. Nano-waste is different than bulk material waste. It’s been seen in laboratory experiments that nanomaterials can enter the human body by dermal exposure, inhalation, and ingestion.36 While there are no specific nanomaterials regulations, yet, there is increasing review and concern both within the industry and in the environmental field as to the fate and behavior of these materials in the environment. Many nanomaterial manufacturers are following bulk material

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Table 4. Nanomaterial characteristics and applicable analytical technologies.

Nanomaterial Characteristics Concentration Particle Size Particle Size Surface Surface Shape Agglomeration Structure Composition Analytical Technique Distribution Charge Area

Inductively Coupled Plasma – Mass Spectrometry ICP-MS

Field-flow Fractionation + ICP-MS FFF-ICP-MS

Liquid Chromatography – Mass Spectrometry LC-MS

Optical Spectroscopy – UV/Vis UV/Vis

Fluorescence Spectroscopy FL

Turbidity

Scanning Electron Microscopy SEM

Transmission Electron Microscopy (+EDX) TEM

Atomic Force Microscopy AFM

Confocal Microscopy

Field Flow Fractionation FFF

Dynamic Light Scattering DLS

Static Light Scattering SLS

Molecular Gas Adsorption (BET) BET

Dialysis

Electrophoresis and Capillary Electrophoresis

Ultrafiltration

Centrifugation

Filtration

Nanoparticle Tracking Analysis NTA

Size Exclusion Chromatography SEC

Selected Area Electron Diffraction SAED

Zeta Potential by DLS

X-ray Diffraction XRD

Thermogravimetric Analysis TGA

Quartz Microbalances

Differential Scanning Calorimetry DSC

Dynamic Mechanical Analysis DMA

Fourier Transform Infrared Spectroscopy FT-IR

FT-IR Imaging

Raman Spectroscopy

TGA coupled with Gas Chromatography – Mass Spectrometry TGA-GC/MS

Laser Induced Plasma Spectroscopy LIPS

Hydrodynamic Chromatography HDC

Laser Induced Breakdown Detection LIBD

X-ray Photoelectron Spectroscopy XPS

Electron Energy Loss Spectroscopy EELS (+EDX)

Commonly used in the characterization of nanomaterials

Microscopy techniques

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Turbidity




Confocal Microscopy





Dialysis


Ultrafiltration

Centrifugation

Filtration











FT-IR Imaging

Raman Spectroscopy







Not widely applicable

Available from PerkinElmer

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regulations and working with the EPA to establish nanomaterial guidelines for health and safety for the workers and for the end users. The EPA has declared that nano- carbon is a new material and use and requires that it be substantiated as safe.37 So airborne nanoparticles, nanoparticles in water, and skin exposure to nanomaterials are being addressed by all parties concerned, but there is much research to be done and a key aspect of this work is the need for methods and analytical techniques that can separate, identify and quantitate ENPs in amongst naturally occurring nanoparticles. As consumers, we should to be aware of nanoparticles in the products we use and the food we eat, but currently there are no labeling regulations. There is legislation being implemented in Europe that requires cosmetic manufacturers to list any nanoparticles used in their products.38,39 This is the first European industry to have required labeling. To date labeling is not required for any other industries anywhere in the world.

Within the United States, the EPA and other government agencies are proactive in regards to nanotechnology. The Federal Government has established the National Nanomaterial Initiative (NNI) where government agencies and private industry meet to discuss and understand nanomaterial implications of the environment and human health. PerkinElmer participates in NNI meetings and is working with the EPA and other agencies to better understand nanomaterials. Figure 8 depicts the life cycle of nanomaterials in the environment and identifies what government agencies are addressing these segments of the life cycle. The source and emission in Figure 8 corresponds to the manufacturing waste in figure 7. The waste interaction with the environment could occur from material taken to a dump, incinerated or washed down the drain. Environmental Health and Safety (EHS) applies to nanomaterial workers as human exposure could occur during the manufacturing process.

Figure 8. Nanomaterial life cycle in the environment.Source: DOE Molecular Foundry – Lawrence Berkeley National Laboratory.

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Q What solutions are provided by PerkinElmer for nanomaterials characterization?A Although nanomaterials are small and cannot be seen with the naked eye, it seems likely

that their impact on the world will be huge. PerkinElmer is involved in the nanomaterial revolution by participating and working with government agencies, research universities, nanomaterial manufacturers, and end-user industries. While PerkinElmer does not supply all the possible measurement technologies required as listed in Table 4, in certain important areas we have a rich solution offering to enable customers to make critical measurements. As customers discover what measurement parameters and performance criteria are important, we believe that our offerings will deliver more value and come to be recognized as important solutions to challenging problems.

PerkinElmer has the following solutions available for customers who require nanomaterial characterization:

Table 5. PerkinElmer analytical solutions.

Analytical Technology Application

UV/Vis The LAMBDA™ 850/950 are being used to assess nanomaterial surface coating on glass for the solar energy industry. The LAMBDA 1050 equipped with a 150 mm integrating sphere has been used to measure the band gap (an important semiconductor characteristic) of TiO2 nanomaterials.40

Fluorescence The LS-55 is being used to measure the fluorescence shift in quantum dots. In addition, quantum dots are being considered as reference materials to calibrate fluorescence spectrometers.41

FT-IR Photocatylitic degradation of dyes and other photosensitive materials. Use of FT-IR imaging to examine gold nanostructures embedded in 50 nm thin polymethylmethacrylate film to develop novel materials.40

Raman Surface characterization of films and other substrate materials that are coated with nanomaterials.

TGA Pyris™ 1 TGA finds application in characterizing CNTs during the manufacturing process and for incoming inspection.

DSC DSC 8500 is being used to characterize amorphous pharmaceuticals that employ nanomaterials such as determining the glass transition temperature (Tg) to assess the nano-crystalline structure.40 StepScan™ and HyperDSC® have been used to study the rigid amorphous fraction in polymethylmethacrylate silicon oxide nano-composites.42

DSC-Raman Morphology characterization of SWCNTs in composites.

DMA To assess the strength of different composite mixtures of CNT/epoxy.

TGA-GC/MS Being used by an EPA lab to measure the degree of coating on ENPs under different conditions.

AA Mainly used to measure bulk concentrations in fabricated materials such as Ag nanoparticle impregnated fabrics [Ag in textile/Germany].

ICP Assessment of gold and copper concentration in digests of elemental nanomaterial suspensions.43

ICP-MS Rapidly becoming the elemental measurement technique of choice for ENPs, especially Au, Ag, Pt, Ce, W, Ti, etc. in the environment and increasingly being coupled with Field Flow Fractionation. In a recent review article on this hyphenated technique, of the 28 papers referenced, 18 used PerkinElmer® ICP-MS systems.31 Researchers are now looking to perform single particle analysis with ICP-MS as this gives additional size and distribution information.44

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PerkinElmer is an active member of the ISO group establishing nanomaterial testing protocols and participates in NNI meetings and a variety of international nanomaterial scientific meetings.

Q Where can I find more information?A To learn more about PerkinElmer analytical solutions for nanomaterial applications,

please visit http://www.perkinelmer.com/nano. This will continue to develop in the future to provide access to key scientific publications, background information, application notes and links to useful websites.

This ‘Primer’ is intended to provide you with useful background information; it cannot answer every question, but it should stimulate material characterization discussions that hopefully will lead to an analytical solution.

Have questions, need more information? Please contact Andrew Salamon, Patrick Courtney or your local PerkinElmer sales representative. We are happy to answer your nano-related questions.

References

1. Burnett, K., and Tyshenko, M.G., (2010), A comparison of human capital levels and the future prospect of the nanotechnology industry in early sector investors and recent emerging markets, Intl. J. of Nanotechnology, 7, 2/3, 187-208. http:// www.inderscience.com/browse/index.php?journalID=54&year=2010&vol=7&issue=2/3

2. American Heritage Dictionary, March 2010. http://dictionary.reference.com/ browse/Nanotechnology

3. International Standards Organization, 2008, ISO/TS 27687:2008 and 2010, ISO/ CD TS 80004-1:2010

4. Klaine, S.J., Alvareez, J.J., Batley, G.E., et al., (2008), Critical Review, Nanomaterials in the environment: behaviour, fate, bioavailability and effects, Environ. Toxicol. Chem, 27, 1825-1851

5. National Nanomaterial Initiative, March 2010: http://www.nano.gov/Nanotechnology_ BigThingsfromaTinyWorldspread.pdf

6. National Nanomaterial Initiative, March 2010: http://www.nano.gov/html/facts/faqs.html

7. Nature, (2009), 461, 1036-1037, doi: 10.1038/4611036a

8. National Nanomaterials Initiative, 2010, Supplement to the President’s FY2011 budget http://www.nano.gov/NNI_2011_budget_supplement.pdf

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9. Gion, A., (2010) Bucky Balls, March 2010: http://www.3rd1000.com/bucky/bucky.htm

10. Evident Technologies, (March 2010): http://www.evidenttech.com/quantum-dots- explained/how-quantum-dots-work.html

11. Nanoco Group PLC website, (2010), http://www.nanocotechnologies.com/content/ AboutUs/AboutQuantumDots.aspx

12. Nanocomposix Corp., (March 2010): http://www.nanocomposix.com/product-gold/ nanoxact-gold.html

13. Li, D., Wang, Y., Xia, Y., (2004), Electrospinning Nanofibers as Uniaxially Aligned Arrays and Layer-by-Layer Stacked Films, Adv. Matls., 16, 4, 361-366, DOI 10.1002/adma.200306226, http://www3.interscience.wiley.com/journal/107630203/ abstract

14. Patel, S., Li, S., (2007), Bioactive Aligned Nanofibers for Nerve Regeneration, Nanotech Conference, Santa Clara, CA, USA. http://www.nsti.org/BioNano2007/ showabstract.html?absno=1301

15. Hegde, R.R., Dahiya, A., Kamath, M.G., (2005), Nanofiber nonwovens, http://web. utk.edu/~mse/Textiles/Nanofiber Nonwovens.htm

16. Woodrow Wilson Center for Scholars, Project on Emerging Technologies (2010), http://www.wilsoncenter.org/index.cfm?topic_id=166192&fuseaction=topics.home

17. Nanoiron Future Technology, Rajhard, Czech Republic, http://www.nanoiron.cz/en/ home-page

18. Moriggi, L., Cannizzo, C., Dumes, E, et al., (2009), Gold Nanoparticles Functionalized with Gadolinium Chelates as High-Relaxivity MRI Contrast Agents, J. Am. Chem. Soc., 131 (31), pp 10828–10829, DOI: 10.1021/ja904094t,

19. Nanovations Pty, Ltd., New South Wales, Australia, (2010), http://www.nanovations.com.au/index.htm

20. Nanocor, USA, www.nanocor.com

21. A to Z of Nanotechnology website, (2010), http://www.azonano.com/details.asp? ArticleID=1339

22. Yang, W., Peters, J.I., Williams III, R.O., (2010), Inhaled nanoparticles – a current review., Int. J. of Pharmaceutics, 356, 1-2, 239-247, doi:10.1016/j.ijpharm.2008. 02.011

23. 3XDRY® Essex Fishing Shirt, (2010). http://www.simmsfishing.com/site/3xdry_essex_ shirt.html#

24. PuckSkin Hockey Apparel, BC, Canada, (2010), http://www.puckskin.com/home.htm

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26. Federal Aviation Administration, Fire Safety Division, Washington DC, USA, (2010), http://www.fire.tc.faa.gov/research/targtare.stm

27. Energenics web page, suppliers of Envirox™ http://www.energenics.org/envirox.html

28. Holmenkol AG, Germany, (2010), http://www.nanowax.de/index.php?id=10&L=1

29. Easton Sports Inc., CA, USA, http://eastonbike.com/

30. Goa, F., University of Nottingham Trent, UK, January 26, 2010, Lecture Presentation

31. Dubascoux, S., Le Hecho, I., Hassellöv, M., et al, (2010), Field-flow fractionation and inductively coupled plasma mass spectrometer coupling: History, development and applications. J. Anal. Atom. Spectrom, DOI: 10.1039/b927500b, web prepublication 23-March-2010

32. Postnova Corp., Germany, (2010), http://www.postnova.com/

33. Wyatt Technology Corporation,USA, (2010), http://www.wyatt.com/

34. Mansfield,E., Kar, A, Hooker, S.A., (2010), Applications of TGA in quality control of SWCNTs, Anal. Bioanal. Chem., 396(3), 1071-1077.

35. Sahle-Demesie, E., EPA, USA, (March 2010), Personal communication with A. Salamon, PerkinElmer

36. National Nanotechnology Initiative - Human Health Workshop (2009), Washington DC., USA, November 17 – 18.

37. Environmental Protection Agency, Washington DC, USA, (2010), Control of nanoscale materials under the Toxic Substances Control Act, http://www.epa.gov/oppt/nano/

38. European Union Cosmetics directive, 76/768/EEC, 25 March 2009

39. Bowman, D.M., van Calster, G., Friedrichs, S., (2010), Nanomaterials and regulation of cosmetics, Nature Nanotechnology 5, 92 doi:10.1038/nnano.2010.12

40. Courtney, P., (2009), Functional measurements in nanomaterisals using optical and thermal techniques, PerkinElmer poster presented at the 3rd Nanomaterials Conference, Bonn, Germany, 16 – 18 June. http://www.nanotechia.org/events/ nanomaterials-2009

41. Upstone, S., Seer Green, UK, (2008), PerkinElmer Presentation, Colloquium on Optical Spectroscopy (COSP), Berlin, Germany

42. Schick, C., (2009), Study Rigid Amorphous Fraction in Polymer Nano-Composites by Step Scan and Hyper DSC, PerkinElmer Application Note #008648_01

43. Sarojam, P., (2010), Elemental characterization of gold and copper nanoparticles with ICP-OES, PerkinElmer Application Note (in preparation)

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44. Heithmar, E.M., and Siska, E.M., (2010), Single particle-inductively coupled plasma mass spectrometry of metal-containing nanomaterial in surface waters around Las Vegas, Nevada, USA, Poster presentation at the 2010 Winter Conference on Plasma Spectrochemistry, Fort Myers, Florida, USA, January 4-9.

Useful books and websites for more information

Nanochemistry – A Chemical Approach to Nanomaterials, 2nd Edition, (2009), Ozin, G.A., Arsenault, A.C., Cademartiri, L.,RSC Publishing, Cambridge, UK, ISBN: 978-1-84755-895-4

Introduction to Nanoscience, (2010), Lindsay, S.M., Oxford University Press, Oxford, UK, ISBN: 978-019-954420-2

PerkinElmer Nano Applications Library, http://www.perkinelmer.com/nano

U.S. National Nanomaterials Initiative (NNI), http://www.nano.gov/

University of California Center for Environmental Implications of Nanomaterials, USA, http://cein.cnsi.ucla.edu/pages/

Duke University Center for the Environmental Implications of Nanotechnology, USA, http://www.ceint.duke.edu/

U.S. Department of Defense, Nano-Funding, http://nanosra.nrl.navy.mil/funding.php

Current Government Nanomaterial Solicitations, http://www.nano.gov/html/funding/currentsol.html

Nanotechnology Nanomaterial Suppliers, http://www.nanowerk.com/nanotechnology/nanomaterial/suppliers_plist.php?subcat1=np

Overview of ground water treatment and chemistry with nano zerovalent iron, http://cgr.ebs.ogi.edu/iron/

UK-based nanotechnology forum intended for anyone who wants to learn more about this technology, products etc., http://www.nanoandme.org/home/

Nanotechnology Now information forum, http://www.nanotech-now.com/nano_intro.htm

A to Z Nanotechnology, a free-to-access nanotechnology website, http://www.azonano.com/default.asp

Nanotechnologies Industry Association, Brussles, Belgium, (2010), http://www.nanotechia.org/content/aboutus/

The Nanotube Site. Very comprehensive listing of information and publications on carbon nanotubes. (2010). http://www.pa.msu.edu/cmp/csc/nanotube.html

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Looking for other ways to learn more about Nanotechnology? There are many different resources available that allow scientists to explore the depths of the Nanotechnology world.

Please see below for some recommended online resources:

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LinkedIN Groups: • Nanotechnology in Drug Delivery • Nanotechnology Zone • Nanotechnology : Materials and Fabrication

Websites • Nano.gov• http://sis.nlm.nih.gov• www.perkinelmer.com/nano

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Whitepaper Nanopharmaceuticals

Author

Andrew W. Salamon Sr. Staff Scientist

PerkinElmer, Inc. Shelton, CT USA

Introduction

“Nanotechnology is widely anticipated as one of the key technologies of the 21st century.”1 PerkinElmer supplies nanomaterial characterization instruments for industrial and academic nanotechnology research. Industrial nanotechnology

applications are far-reaching, spanning all science and engineering disciplines. One of the most promising nanotechnology fields is Nanopharmaceuticals. Because nanomaterials may enter the body through dermal exposure, inhalation, ingestion, or ocular contact, they lend themselves to innovative drug delivery systems. Pharmaceutical research, toxicology studies, formulation, and manufacture of pharmaceutical products require material characterization to ensure consistent drug safety and effectiveness. PerkinElmer has been providing analytical instruments to the pharmaceutical industry for more than 60 years. As such, nanopharmaceutical material applications are no exception for PerkinElmer.

What are Nanomaterials?

Nanomaterials are materials that range in size from approximately 1 nm to 100 nm. There are more rigorous definitions that are specific to certain applications such as cosmetics. In Europe’s efforts to label cosmetics that contain nanoparticles, this definition evolved: “nanomaterial means an insoluble or biopersistant and intentionally manufactured material with one or more external dimensions, or an internal structure, on the scale from 1 to 100 nm.”2

Nanopharmaceuticals and PerkinElmer

Nanomaterials

Copyright ©2010, PerkinElmer, Inc. All rights reserved. PerkinElmer is a registered trademark of PerkinElmer, Inc. All other trademarks are the property of their respective owners. 009227_01

PerkinElmer, Inc.940 Winter StreetWaltham, MA 02451

This poster compares the nano-region to things we know, such as a pin, insect and cells to provide a visual perspective. Nanotechnology is the science and technology of precisely manipulating the structure of matter at the molecular level.

For Nanomaterial Applications, please visit www.perkinelmer.com/nano

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Engineered nanoparticles are of great scientific interest. They effectively bridge a gap between bulk materials and atomic and molecular structures. Nanoparticle mechanical properties are different than bulk material. Surface area is disproportionate to weight, for instance, an 8 nm gold material has a surface area of 32 square meters per gram. Materials of nanoscale proportions exhibit unique characteristics. Examples are gold nanopartilces and silver nanoparticles smaller than 12 nm that exhibit an affinity for magnetism. In bulk form gold and silver are non-magnetic.

There is a diverse field of applications over a broad range of industries:

• Energy,energy-conservation,pharmaceuticals,chemicals,catalysts

• Highperformance-compositeengineeredmaterials– military to leisure time applications

• Coatings,electronics,sensorsanddisplays

• Andmore

What materials are used to make Engineered Nanomaterials?

There are several categories of nanomaterials, naturally occurring nanomaterials are found in nature, engineered nanomaterials are synthesized for a specific purpose or function, manufactured nanomaterials are produced for commercial purposes, and incidental nanomaterials are generated as an unintentional by-product of a process.3

Some engineered nanomaterials are:

• Gold,Silver,Copper,Selenium,Iron,Titanium,Zinc,andAluminum

• Zincoxide,Titaniumoxide

• Carbon–CarbonNanotubes,Buckyballs,andGraphene.

• Clay

• Organicmaterials/biodegradable

What material parameters are important?

To completely characterize nanomaterial it is necessary to know a multitude of chemical and physical pararmeters including: the size of the particle, their shape, surface characteristics, the presence of surface coatings, and the presence of impurities.

Consequently,atthenanoscale,analyticalmeasurementchallenges are considerable and the ability to use, for example, one technique such as inductively coupled plasma andmassspectrometry(ICP-MS)tomeasuretheelementalconcentration of gold in a suspension as the only metric, does not provide enough information.

How are engineered nanomaterials measured?

Seven of the nine nanomaterial characteristics: ParticleSize,SizeDistribution,SurfaceCharge, Surface Area, Shape, Agglomeration, and Structure, are characterized by one of the following analytical techniques:

• ScanningElectronMicroscopy(SEM)

• TransmissionElectronMicroscopy(TEM)

• AtomicForceMicroscopy(AFM)

• ConfocalMicroscopy(CFM)

• DynamicLightScattering(DLS)

• FieldFlowFractionation(FFF)

• MolecularGasAdsorption(BET)

• ElectrophoresisParticleSize

Note

Ultraviolet/Visible Spectroscopy and Fluorescence Spectroscopy are used for particle size identification as long as the material is known and it is reflective. Fluorescence Spectroscopy is also used for agglomeration studies.

NanoparticleConcentrationandCompositionaretwonano-particle characteristics that that are not covered by the analytical techniques described in the paragraph above. There are many analytical techniques that do cover concen-tration and composition. The correct analytical technique is determined by the material, coatings, and nano application.

ForNanoparticleConcentrationyoumightchooseoneorseveral of the following analytical techniques:

• InductivelyCoupledPlasmaandMassSpectroscopy (ICP-MS)

• LiquidChromatographyandMassSpectroscopy(LC-MS)

• Ultraviolet/VisibleSpectroscopy(UV/Vis)

• FluorescenceSpectroscopy(FL)Key parameters to characterize nanomaterials.

Figure adopted from Hassellöv, M., and Kaegi, R., Analysis and characterisation of manufactured nanoparticles in aquatic environments, Chapter 6 in Environmental & Human Health Impacts of Nanotechnology, Eds., Lead, J.R. & Smith, E., 2009 Blackwell Publishing Ltd.

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For Nanoparticle Composition you might choose one of the following analytical techniques:

• InductivelyCoupledPlasmaandMassSpectroscopy(ICP-MS)

• LiquidChromatographyandMassSpectroscopy(LC-MS)

• Ultraviolet/VisibleSpectroscopy(UV/Vis)

• FluorescenceSpectroscopy(FL)

• Thermogravimetry(TGA)

• DifferentialScanningCalorimetry(DSC)

• DynamicMechanicalAnalysis(DMA)

• FourierTransformInfraredSpectroscopy(FT-IR)

• RamanSpectroscopy

• Thermogravimetry,GasChromatography,andMassSpectroscopy(TGA-GC/MS)

• ThermogravimetryandMassSpectroscopy(TGA-MS)

For composition, you may be concerned with purity or the coatings on nanomaterials besides the substrate material of the nanoparticle. All of the italicized analytical techniques are nano-characterization instruments that PerkinElmer offers. Please remember that there is not just one analytical technique that can characterize a nanomaterial. All analytical techniques are also listed in Table 1.

What pharmaceutical applications are likely to utilize nanomaterials?

Nanopharmaceutical markets include products for humans, pets, and Farm animals. From the list below you can see that nanotechnology innovation will affect most people:

• Medicines for most diseases and illnesses – tablet or liquid form

• Vaccines for most diseases and illnesses

• Chemotherapeutic agents

• Anti-cancer drugs

• Personal care products: shampoos and body washes, etc.

• Medical devices and diagnostics, Molecular diagnostics, Diagnostic tests

• Dental health products

• Over-the-counter medicines

• Nutritional products

• Managing-obesity products

• Medical and Surgical devices

• Ocular health products and instruments

• Cardiology and Pulmonary medicine

• Osteoporosis

• Injury healing

• Generic pharmaceuticals

• Smoking cessation

Who is involved in Nanopharmaceuticals?

all major pharmaceutical companies are involved in Nanopharmaceuticals.

• GlaxoSmithKline (GSK)

• Merck

• Johnson & Johnson

• Novartis

• Pfizer

Small “start-up” nanopharmaceutical companies play an important role in research and development. Some not-so-well-known, small, new, nanopharmaceutical-focused companies are:

• Cerulean Pharma Inc.

• Bind Biosciences

• Selecta Biosciences

all U.S. universities that conduct pharmaceutical or medi-cal research are involved in nanopharmaceuticals. Some of the most well known academic nano-research institutions are:

• UCLA

• Rice University

• Georgia Tech

• MIT

• Yale University

• Many more…

academic authors of nanopharmaceutical scientific research papers span the globe. They originate from:

• Iran

• Israel

• Poland

• Italy

• Germany

• Russia

• China

• Australia

• Japan

• UK

• Many more…

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Turbidity




Confocal Microscopy





Dialysis


Ultrafiltration

Centrifugation

Filtration











FT-IR Imaging

Raman Spectroscopy







Commonly used in the characterization of nanomaterials

Microscopy techniques

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Turbidity




Confocal Microscopy





Dialysis


Ultrafiltration

Centrifugation

Filtration











FT-IR Imaging

Raman Spectroscopy







Not widely applicable

Available from PerkinElmer

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Nanomaterials are used primarily for drug delivery systems, but also are used for product packaging, colorants; bone, skin, and muscular growth; and medical imaging.

Drug delivery systems can be simple such as gold nano-particles coated with a vitamin or nutrient. Or it could be as complex as a nanoparticle that is coated with functional groups that target specific tumor cells or organs and then are able to release the drug in some manner; time-released, released by heat, released by light, or released by magnetism. There are even nano-delivery systems that seek and destroy cells by entering the targeted cells and explode. Thus exploding within the cell and completely destroying the cell. Some time-released nanopharmaceuticals are encapsulated in lipids for use in salves and ointments. Titanium Oxide nanoparticles are used for white colorant in some salves and ointments and also in Dental Health products.

Below is a diagram of a product from Selecta Biosciences Company. this complex nanopharmaceutical delivery system is designed to combat an influenza virus.5

tSVp™ – a new class of synthetic vaccines for Optimal immune response

Selecta’s targeted Synthetic Vaccine Particle (tSVP™) product platform enables, for the first time, the highly-precise and modular development of therapeutic and prophylactic vaccines with optimal efficacy, duration of coverage and safety, to greatly improve the lives of patients.

Selecta’s tSVP™ platform creates fully-integrated synthetic nanoparticle vaccines engineered to mimic the properties of natural pathogens to elicit a maximal immune response. The tSVP™ vaccines are rationally designed to optimize the presentation of antigens to the nexus of the immune system and ensure a focused and undistracted response. Selecta’s tSVP™ platform accomplishes this by delivering antigens and adjuvants, within the same biodegradable nanoparticle, directly to antigen-presenting cells. This approach maximizes the immune response while minimizing undesirable off-target effects.

Selecta’s unique tSVP™ platform includes a self-assembling nanoparticle platform that is synthetic, modular, and engi-neered for highly-effective targeting to immune cells. The tSVP™ vaccines incorporate only the essential elements required for a specific, robust immune response, based on precise engineering that is only possible with Selecta’s proprietary, nanoparticle self-assembly process.

Below is a diagram of a product from Bind Biosciences inc. that describes another type of complex nanopharmaceutical delivery system.6

Targeted Nanoparticle Platform

BIND’s targeted nanoparticles consist of the following components that facilitate optimization and control:

targeting ligand provides recognition, enabling targeted nanoparticles to identify and bind to their intended target site. They are designed to recognize specific proteins or receptors that are found on the surface of cells involved in disease or the surrounding extracellular matrix.

Surface functionalization shields targeted nanoparticles from immune surveillance, while providing attachment for the targeting ligand through proprietary linkage strategies. We have developed proprietary methods for precisely controlling the surface characteristics necessary to ensure the drug is delivered efficiently and consistently.

polymer matrix encapsulates payload molecules in a matrix of clinically validated biodegradable and biocompatible polymers that can be designed to provide the desired drug release profile.

therapeutic payloads can be incorporated into our targeted nanoparticles, including small molecules, peptides, proteins and nucleic acids, such as siRNA.

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CRLX101

CRLX101 is comprised of the high potency anti-tumor agent camptothecin coupled to a cyclodextrin based polymer that self-assembles into nanoparticles of consistent size and other physical attributes.

Below is a schematic representation of CRLX101.

CRLX101 provides clinical validation of the CDP technology improving the tolerability of the parent drug camptothecin. Results from the Phase 1 clinical study of CRLX101 have shown that it has a favorable safety profile in patients with advanced cancer. Combining camptothecin’s potency and Cerulean’s nanopharmaceutical design features, we believe CRLX101 has the potential to kill tumor cells while minimizing the side effects typically associated with chemotherapy treatment.

It is easily noted that all three nanopharmaceutical delivery systems are very different and all require material character-ization by some analytical technique. This ensures patient safety and product effectiveness for each.

Amazing results

When nanopharmaceutical drug delivery systems as sophisti-cated as the three above are used in certain cancer cases the results have been better than traditional bulk chemotherapy with little or no side effects.

Below are excerpts from Cerulean Pharma Inc. clinical and pre-clinical Nanopharmaceutical data for their product CRLX101 and progress with pre-clinical lead CRLX288.

Cerulean Chief Medical Officer John Ryan, Ph.D., M.D., reported results from the dose-finding, safety and tolerability Phase 1 clinical study of CRLX101. Specifically, Dr. Ryan discussed data establishing the maximum tolerated dose and the recommended dose and schedule for a planned Phase 2 study. He reviewed observations of progression-free disease of greater than six months in five advanced cancer patients

who had previously relapsed and progressed on multiple lines of prior therapy. Notably, these advanced cancer patients had highly aggressive tumor types, such as non-small cell lung and pancreatic cancer, with typical survival of less than six to eight months. These observations corre-late with CRLX101’s pharmacokinetics profile including an extended half-life of more than 30 hours and a low volume of distribution of 2.1 liters per square meter, an indication of low systemic exposure of free drug. These data are also consistent with animal pharmacokinetic data demonstrating a high and prolonged localized drug exposure in the tumor.

Cerulean Senior Director of Research Scott Eliasof, Ph.D., presented recent results on the Company’s pre-clinical lead candidate, CRLX288, a docetaxel nanopharmaceutical. His presentation focused on animal studies showing a significant improvement in the therapeutic index of CRLX288 compared to the parent drug docetaxel. Specifically, Dr. Eliasof reported that CRLX288 achieved complete regression and inhibition of tumor growth in 100 percent of the animals studied for greater than 100 days post-treatment, at dose levels that were well tolerated, in both typical size xenograft tumors of 100 mm3 as well as in xenograft tumors as large as 800 mm3. CRLX288’s superior efficacy over the parent drug docetaxel in animal studies was consistent with other pre-clinical findings showing 20 times more drug accumulating in the tumor as compared to treatment with free docetaxel [bulk material].

Together, the Phase 1 findings for CRLX101 and the pre-clinical data on CRLX288 demonstrate that Cerulean’s nanopharmaceutical platform has the potential to markedly enhance efficacy and tolerability of therapeutic agents in humans. Such biological outcome is targeted to be achieved with drug-containing nanoparticles that are designed to remain intact in circulation, accumulate in tumor tissues, enter cancer cells, and provide a long and sustained drug effect with slow and controlled drug release.

Please note that CLRX101 delivers the drug, camptothecin. Camptothecin is very potent and when delivered in bulk form not only killed the tumors but in some cases killed patients. When the same dosage of camptothecin is deliv-ered in nanoscale increments the drug is still as effective as in bulk delivery, but there are no side effects. This maybe a result of attacking the tumor on a cell by cell basis. In fact, in laboratory tests a double dose of camptothecin bulk form was delivered on the nano scale and there were still no side effects.9

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camptothecin (CPT)

b-cyclodextrin (CCD)

polyethylene glycol (PEG)

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PerkinElmer diligently works at being a global leader in nanotechnology characterization. PerkinElmer participates in Nano seminars worldwide. PerkinElmer is a member of the U.S. Technical Advisory Group (TAG 229) within the International Standards Organization (ISO). This member-ship involves writing and reviewing ISO Nanotechnology documents for industry, including nanopharmaceuticals and toxicology applications. PerkinElmer also participates in the U.S. National Nanotechnology Initiative (NNI) which helps set U.S. strategic direction for nanotechnology. PerkinElmer is a leader in material characterization and with its strength in characterizing nanomaterials it is very well positioned as a leader in nanopharmaceuticals. These are truly exciting times in nanoscience.

Additional Readings and websites

• Nanotechnology and Engineering Nanoparticles – A Primer.

• Nanopharmaceutical Applications Library

Both suggested readings above are found www.perkinelmer.com/nano

• U.S. National Nanomaterials Initiative (NNI), http://www.nano.gov/

• University of California Center for Environmental Implications of Nanomaterials, USA, http://cein.cnsi.ucla.edu/pages/

• International Standards Organization, http://www.iso.org/iso/home.htm

References

1. Novartis Pharmaceuticals Corp. 2006, accessed Jan 2011, http://www.corporatecitizenship.novartis.com/downloads/business-conduct/Nanotechnology_Based_Medicines_External_Position.pdf

2. Lövestam, G., Rauscher, H. et al, Considerations on a Definition of Nanomaterial for Regulatory Purposes,

For a complete listing of our global offices, visit www.perkinelmer.com/ContactUs

Copyright ©2011, PerkinElmer, Inc. All rights reserved. PerkinElmer® is a registered trademark of PerkinElmer, Inc. All other trademarks are the property of their respective owners. 009561_01

PerkinElmer, Inc. 940 Winter Street Waltham, MA 02451 USA P: (800) 762-4000 or (+1) 203-925-4602www.perkinelmer.com

European Commission Joint Research Center (JRC), 2010.

3. International Standards Organization (ISO), Tech Spec ISO/TS80004-1 Nanotechnologies – Vocabulary Part 1: Core Terms.

4. Hasselhov, M., Kaegl, R., “Analysis and Characterization of Manufactured Nanomaterials in Aquatic Environment,” Chapter 6 of Environmental and Human Health Impacts of Nanomaterials, Eds. Lead, J. and Smith, E,. Blackwell Publishing Ltd.

5. Selecta Biosciences, 2011, Accessed Jan 2011, http://www.selectabio.com/product-platform/index.cfm

6. Bind Biosciences, Inc. 2010, Accessed Jan 2011, http://www.bindbio.com/content/pages/technology/index.jsp

7. Cerulean Pharma Inc. Clinical Trials, Accessed Jan 2011, http://www.ceruleanrx.com/clinical_trials.html

8. Cerulean Pharma Inc. Press release, Nov 2010, accessed Jan 2011, http://www.ceruleanrx.com/Press/CeruleanPressRelease_120910.pdf

9. Glucksmann, A., Cerulean Pharma Inc., Dr. Clucksmann’s presentation at the NNI Summit meeting, Washington, DC, Dec 10, 2010.

10. Cerulean Pharma Inc., Press release, Cerulean Pharma Inc. Senior Executive to Present at the National Nanotechnology Innovation Summit, Dec 9, 2010, http://www.ceruleanrx.com/Press/CeruleanPressRelease_120910.pdf

11. Salamon, A.W. and et al, PerkinElmer, 2010, Nanotechnology and Engineering Nanoparticles – A Primer.

12. PerkinElmer Nanomaterials website, Nanopharmaceutical Applications Library, www.perkinelmer.com/nano

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Thermal Analysis • ImprovedHyperDSCMethodtoDetermineSpecificHeatCapacityofNanocompositesandProbeforHigh-TemperatureDevitrification

• A Study of Aged Carbon Nanotubes by Thermogravimetirc Analysis

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Introduction

There has been tremendous interest in recent years in nanocomposites – using small scale particulate fillers – to improve the properties of thermoplastics and thermosets. For example, the effect of using such small scale filler particles is such as to toughen the plastics, reduce vapor transfer, and improve transparency. One rapid way to quantify the effect of a particular filler formulation is to measure its effect on the change in specific heat (Cp) that occurs at the

glass transition (Tg). In this analysis, discussed by Christophe Schick,1 the Cp of an amorphous nanocomposite can be usefully partitioned between three entities: (1) unaffected amorphous polymer whose properties are the same as that in the pure amorphous polymer, called the mobile amorphous fraction; (2) the Cp of the filler itself; and (3) the Cp of the polymer which is immobilized by its attachment to the nanoparticle, the rigid amorphous fraction (RAF). The properties of the composite can be related to the extent of these fractions. The chemical bonding – weak or strong – of the RAF to the nanomaterial filler may be an indicator of the performance of the nanocomposite, and it may be an indicator of how readily it will decompose in the environment. A second Tg – devitrification of the RAF – would indicate a relatively weak bond of the RAF to the nanomaterial filler.

Differential Scanning Calorimetry

a p p l i c a t i o n n o t e

Authors

Bruce Cassel1

Andrew Salamon1

E. Sahle-Demessie2

Amy Zhao2

Nicholas Gagliardi3

1 PerkinElmer, Inc. Shelton, CT, USA

2 U.S. Environmental Protection Agency Cincinnati, OH, USA

3 University of Dayton Research Institute Dayton, OH, USA

Improved HyperDSC Method to Determine Specific Heat Capacity of Nanocomposites and Probe for High-Temperature Devitrification

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Experimental and Data Handling

The instrument employed for this analysis was the PerkinElmer® DSC 8500, a power-controlled, dual-furnace differential scanning calorimeter (DSC) with the ability to scan at rates up to 750 ˚C/min and achieve rapid equilibration, a requirement when using rapid scan rates. The purge gas was helium. The block heat sink temperature selected was -180 ˚C, with the cooling provided by the CLN2 liquid nitrogen cooling accessory. Calibration used the two melting standards indium and lead. Encapsulation was with aluminum HyperDSC pans, which are low mass and provide optimum thermal coupling (Part No. N5203115).

When PerkinElmer Pyris™ software’s AutoSlope function is selected in Preferences, all runs are automatically shifted and sloped to zero heat flow using the final heat flow points of the highest and lowest temperature isotherms. To convert to Cp units, one subtracts the iso-aligned baseline data and then selects Single Curve Cp from the Calculate/Specific Heat menu. The result is a specific heat data curve as a function of temperature tested that can be plotted, further analyzed, and saved (Figure 2).

This method enabled the specific heat to be obtained up to 300 ˚C without appreciable error from decomposition. The data was delivered to the supplier of the nanocomposites in the form of tables created in Pyris and transferred into a spreadsheet (Figure 3).

Background

Christophe Schick demonstrated the use of the HyperDSC® technique to measure RAF and to look for evidence of devitrification of the RAF in the temperature region between the glass transition temperature (Tg) and the rate-suppressed onset of decomposition. He demonstrated how this Cp data, made accurate by corroborative use of StepScan™ methods, could be compared to the Cp function of neat polymer to further evaluate the degree of agglomeration of filler in a nanocomposite.1

The key relationship in his paper for quantifying the RAF in a composite is:

RAF = 1 – Filler Content –

Where ΔCp and ΔCp pure are the changes in specific heat at the glass transition temperature, Tg, for the composite, and for the unfilled polymer, respectively.

This work suggests an alternative method for determining Cp that takes advantage of fast heating and cooling rates to obtain quantitative Cp in the upper temperature region without having to dwell in that high temperature region to establish an upper isothermal.

In the conventional method to measure Cp (ASTM® E1269), a sample is equilibrated at a low temperature and then heated at some rate to an upper temperature where the temperature is again held constant until there is full equilibration. The problem with the conventional Cp method – and with modulated temperature methods – is that the sample is likely to degrade when held at high temperatures, and this degradation compromises the accuracy of measurement.

In the method suggested here, the temperature program for the sample (and baseline) is that of heating at a very rapid rate (here 400 ˚C/min) to the upper temperature, then immediately cooling at the same rapid rate to a temperature sufficiently low with little or no sample decomposition. Figure 1 shows the raw data, including sensor temperature and heat flow.

Figure 1. Raw data for thermoplastic polyurethane nanocomposite using the 400 ˚C/min heat-cool Cp method – analysis time: 5 minutes.

Figure 2. Specific heat capacity data for thermoplastic polyurethane composite using the 400 ˚C/min heat-cool Cp method, with Tg and peak calculations applied.

Figure 3. Microsoft® Excel® spreadsheet, for further analysis of Cp data, after transferring a table from Pyris software.

∆Cp pure

∆Cp

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of this devitrification effect in the formulation (PMMA and SiO2) he investigated, but we wanted to provide a rapid method of assessing other formulations for this effect. In the (proprietary) nanocomposite samples we evaluated, we observed some evidence of increased Cp at higher temperatures, but further work would be required – including analyzing the unfilled plastics – to make any definitive statement about devitrification.

Conclusions

HyperDSC shows promise for elucidating nanocomposites. The use of a rapid heat-cool method, such as demonstrated here, extends the upper temperature range for which accurate specific heat capacity measurements are practical. This should help identify devitrification – loss of nanocomposite bonding – in the amorphous polymer system. This method further extends the utility of power-controlled DSC to investigate metastable states of polymer systems.

References

1. Sargsyan, A. Tonoyan, S. Davtyan, C. Schick, The amount of immobilized polymer in PMMA SiO2 nanocomposites determined from calorimetric data, Eur. Polym. J. 43 (2007) 3113-3127.

Assessing Method Accuracy

The goal of this project was to show generation of sufficiently accurate specific heat capacity data from HyperDSC – that the more time consuming StepScan analysis would not be required. To demonstrate accuracy, the same method that produced the above data was also used to analyze the smaller of the two sizes of sapphire specific heat standard in the PerkinElmer Specific Heat Kit (Part No. 02190136). The Cp results were then compared with those in the table that was provided with the kit. The 400 ˚C/min data were in agreement with literature values within 1% from -50 ˚C to 200 ˚C, and within 1.5% up to 320 ˚C. While this accuracy may be somewhat less when running plastics samples because of extraneous effects (e.g., sample inhomogeneity, moisture loss, sample movement, less than optimal thermal coupling), the sapphire test has proven that the new method can be highly accurate with proper sample preparation.

Looking for Evidence of Devitrification

The Schick et al. (2007) investigation was looking for evidence that, at higher temperatures, kinetic energy might free up the rigidly held polymer and reveal a second, but higher and weaker, glass transition attributed to devitrification of the RAF phase. This was the reason for using the HyperDSC technique to otain access to the high-temperature region as well as specific heat data, while kinetically delaying the onset of decomposition. He did not report any evidence

Figure 4. Specific heat capacity of sapphire using the 400 ˚C/min heat-cool method, showing Pyris data, literature data and error.

Figure 5. Specific heat capacity of uncured epoxy nanocomposite using the 400 ˚C/minute heat-cool method, showing possible second Tgs. One interpretation of this data is that the multiple Tgs are due to devitrification of RAF. Not all portions of this sample showed this effect. The sample for analysis was visibly inhomogeneous. Note: at normal DSC scan rates, or when using a modulated technique, decomposition would show additional thermal effects above 200 ˚C, which would mask evidence of devitrification.




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Introduction

Increased use of carbon nanotubes in consumer and industrial products have scientists asking about the implications of CNTs in our environment. Many end product applications include polymer composites, drug delivery systems, coatings and films, military applications, electronics, cosmetics, healthcare, among others.

CNTs are desirable for many applications because of their high surface area to weight ratio. They are lightweight and highly elastic compared to carbon fibers, and deliver higher surface area for increased chemical interaction in its specific application.

Thermogravimetry a simple analytical technique that is frequently used to characterize carbon nanotubes.1 The Pyris™ 1 TGA delivers accurate results quickly because of its low mass furnace. The Pyris 1 TGA low mass furnace has accurate temperature control and fast cooling for higher sample throughput.

Nanotechnology/ Thermogravimetric Analysis


Authors

E. Sahle-Demessie

A. Zhao

U.S. EPA, Office of Research and Development National Risk Management Research Laboratory Cincinnati, OH 45268

A. W. Salamon

PerkinElmer, Inc. Shelton, CT 06484 USA

A Study of Aged Carbon Nanotubes by Thermogravimetric Analysis

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Materials Used

Commercially available high purity MWCNT samples were obtained. Analysis of acid washed samples using ICP showed less than 1% of trace elements.

Table 1 is the manufacturer’s product description before the samples were subjected to UV aging. The far right col-umn explains one of the foremost features of NMs, that is their high surface area in relationship to weight. One gram of Type B CNTs have a surface area that is larger than 200 square meters (>200 m2/g). The manufacturer’s CNT outside diameters are verified by the TEM image in Figure 2.

Table 1. MWCNT Characterization.

Type Purity Outside Specific Diameter Length Surface Area

Type A >95% 8-15 nm ~50µm >233 m2/g

Type B >95% 10-20 nm 10-30 µm >200 m2/g

Type C >95% > 50 nm 10-20 µm >40 m2/g

There are various carbon-nano-material classifications, such as single wall carbon nanotubes (SWCNT), or multi-wall carbon nanotubes (MWCNT). A SWCNT is a single tube of some length with its tubular wall having a hexagonal hollow geometry, similar in shape to a fullerene. A MWCNT is one or more tubes within a tube. Fullerenes, also known as Bucky Balls, are hollow spheres. Graphene is a flat sheet of carbon, one atom thick that has the same hexagonal struc-tural geometry as CNTs. CNTs are made from graphene by wrapping the graphene into cylindrical shapes. Specifications of CNTs may describe their diameter and length, as well as the orientation of the lattice wall in regards to the CNT’s centerline. There are three types of lattice orientations, armchair, zigzag, and chiral. The difference between these CNT types is the bias or angle that they are wrapped.2,4

Figure 1. Types of carbon nanotubes, armchair(n,n), zigzag (n,0) and chiral (Ch). The (n,m) nanotube naming scheme can be thought of as a vector (Ch) in an infinite graphene sheet that describes how to “roll up” the graphene sheet to make the nanotube. T denotes the tube axis, and a1 and a2 are the unit vectors of graphene in real space. This image is the courtesy of Wikipedia.4

Figure 3. This carbon nanotube life cycle diagram depicts waste entering the environment from the CNT synthesis process, the end-product formulation process, and through product end-of-life. The entry into the environment might be an emission into the air, or a release into a river, or product end-of-life entering a landfill. In addition, there are the worker Environmental Health and Safety (EHS) exposures to be considered: dermal exposure, inhalation, and ingestion.3

Figure 2. Above, the Transmission Electron Microscope (TEM) image of CNTs indicates that the CNTs have a ~ 20 nm outside diameter and their lengths are much larger than 200 nm.

During the CNT life cycle: synthesis, end-product formulation, end-use, and product end-of-life, CNTs may enter the environment.

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heating rate, within a short time without consuming too much material. The oxidation rates of carbon nanotubes measured in air at atmospheric pressure within the TGA are unique for each CNT sample of different wall thicknesses. Figure 5 shows the decomposition temperatures (i.e. oxidation) for samples run at the same heating rate, varies up to ±40 ˚C depending on the characteristics of the carbon tubes.

Measuring Aging of Carbon nanotubes

In a laboratory environment, three high purity MWCNT samples that had no specific wrap were analyzed. They were all nearly the same weight and came from the same manufacturing lot. They were subjected to the same UV light source. The intent of the UV light is to simulate sunlight in a controlled manner. Three “A” samples in Figure 5 were exposed to UV for:

• An exposure of 9.0 hours



Results

This experiment results in the CNT amorphous carbon decom-posing before the structural carbon. All carbon should decom-pose in the oxidative environment before reaching 900 ˚C.

Definition: Thermogravimetric Analysis (TGA) also called Thermogravimetry is a technique in which the mass of a material is monitored as that material is subjected to a controlled temperature program in a controlled atmosphere.

MethodA general method follows:

Instrument: Pyris 1 TGA

Sample Size: > 1 mg, usually 3 mg to 50 mg

Sample Pan: Ceramic

Temperature Range: 30 ˚C to 800 ˚C

Scanning rate: 10 ˚C/minute or faster

Sample Purge Gas and Rate: Air at 20 mL/min

Balance Gas and Rate: Nitrogen at a rate at least 10 mL/ min higher than the sample purge rate

Characterization of nanotubes with TGA

Thermogravimetric Analysis was the first analytical technique chosen to compare the effects of the UV exposure times on the CNTs. TGA is very simple, yet a very accurate analytical technique that delivers results quickly. Studying the oxidation of fullerene C60 using TGA has been reported.5,7 The high sensitivity of the TGA, which is in the order of 0.1 micro-gram/min, permitted weight loss determinations at a given

Figure 4. The Pyris 1 TGA.

Figure 5. Thermogravimetric analysis of CNTs showing weight loss. Sample weight was about 10 mg, oxygen flow was 20 mL/min. Samples A, B, C, had varying wall thicknesses. See Table 1 for specifications.

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Figure 6. X Axis = Temperature: When observing Thermogravimetric weight loss curves in regards to temperature, the weight loss curves above indicate that CNTs exposed to UV light for 9 hours began decomposition at a lower temperature than the other two samples of shorter exposures.

Figure 7. X Axis = Time: To gain a better understanding of the results, the same data file is displayed on a Time X-axis. The 1st derivative curve of each weight loss curve is displayed. The 1st derivative is a widely used tool to compliment the TGA weight loss curve, and like the weight loss curve, the 1st derivative curve is very reproducible. Upon examination of the 1st derivative curves above, the CNT sample with the longest UV exposure decomposes more than 5 minutes before the other two samples of shorter exposure times.

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1. Mansfield, E., Kar, A., Hooker, S.A., Applications of TGA in Quality control of SWCNTs, Analytical and Bioanalytical Chemistry, Vol. 369, Number 3, 1071-1077. 2009.

2. Ozin, G.A., Arsenault, A.C., and Cademartiri, L., Nano-chemistry – A Chemical Approach to Nanomaterials, Royal Society of Chemistry, Cambridge, U.K., 2009. Page 209.

3. National Nanotechnology Initiative – Human Health Workshop, November 2009, Washington D.C., US.

4. Wikipedia, Carbon Nanotubes, Nov. 2010, http://en.wikipedia.org/wiki/Carbon_nanotube#Structural

5. Pang L.S.K., Saxby, J.D., and Chatfield, S.P., Thermo-gravimetric Analysis of Carbon Nanotubes and Nano-particles, J. Physical Chemistry, 97, 27, 1993.

6. Saxby, J.D., Chatfield, S.P., et al, Thermogravimetric analysis of Buckminsterfullernce and Related Materials in Air, J. Phys. Chem. 1992, 96,17-18.

7. Joshi, A., Nimmagadda, R., and Herrington, J., Oxidation Kinetics of Diamond, Graphite and Chemical Vapor Deposited Diamond Films by Thermal Gravimetry, J. Vac. Sci. Technol. A 8(3), May/June, 1990.

Additional Reading

PerkinElmer, Nanotechnology and Engineered Nanomaterials – A Primer, www.perkinelmer.com/nano

PerkinElmer, Nanomaterials Reference Library www.perkinelmer.com/nano

Acknowledgement

Special thanks to E. Sahle-Demessie and A. Zhao of the U.S. EPA, January 2011, for providing the TGA data. This thermo-gravimetric data is from an on-going study of environmental effects on carbon nanotubes.

Summary

Based on the Pyris 1 TGA data collected, UV light has an effect on CNTs. As this study suggests, the longer the CNTs are subjected to UV light, the sooner CNTs decompose when heated to elevated temperatures.

Further investigation

Because this is early in an entire series of CNT analytical experiments, there are more TGA tests to conduct. It is suggested that a series of isothermal tests be conducted next. They should involve longer UV exposures and similar exposures to this experiment. Based on the scanning data provided, it is suggested that isothermal tests be conducted at 500 ˚C, 550 ˚C, 600 ˚C, and 650 ˚C. These future isothermal tests would help define the test protocol needed to examine CNTs found in water, soils, or air.

Conclusion

Thermogravimetry by the Pyris 1 TGA is a simple analytical technique that is frequently used to characterize carbon nanotubes. The Pyris 1 TGA delivers accurate results quickly because of its low mass furnace. The Pyris 1 TGA low mass furnace has accurate temperature control and fast cooling for higher sample throughput.




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Workshops, tradeshows and other events are a great way to discuss new scientific discoveries with other innovators in the industry.

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Molecular Spectroscopy • SimpleMethodofMeasuringtheBandGapEnergyValueofTIO2inthePowderFormusingaUV/Vis/NIRSpectrometer

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Introduction

The measurement of the band gap of materials is important in the semi-conductor, nanomaterial

and solar industries. This note demonstrates how the band gap of a material can be determined from its UV absorption spectrum.

The term “band gap” refers to the energy difference between the top of the valence band to the bottom of the conduction band (See Figure 1); electrons are able to jump from one band to another. In order for an electron to jump from a valence band to a conduction band, it requires a specific minimum amount of energy for the transition, the band gap energy1,2. A diagram illustrating the bandgap is shown in Figure 1.

Measuring the band gap is important in the semiconductor and nanomaterial industries. The band gap energy of insulators is large (> 4eV), but lower for semiconductors (< 3eV). The band gap properties of a semiconductor can be controlled by using different semiconductor alloys such as GaAlAs, InGaAs, and InAlAs. A table of materials and bandgaps is given in Reference 1.

UV/Vis/NIR Spectrometer


AuthorJayant Dharma PerkinElmer Technical Center

Aniruddha Pisal Global Application Laboratory PerkinElmer, Inc. Shelton, CT USA

Simple Method of Measuring the Band Gap Energy Value of TiO2 in the Powder Form using a UV/Vis/NIR Spectrometer

Figure 1. Explanation of band gap.

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The optical diagram of the integrating sphere is shown in Figure 4.

An alternative strategy is to use layers of different materials coated onto the silicon base material. This is employed in the solar industry in the construction of photovoltaic (PV) solar cells. The bandgap is important as it determines the portion of the solar spectrum a photovoltaic cell absorbs3. Much of the solar radiation reaching the Earth is comprised of wavelengths with energies greater than the band gap of silicon. These higher energies will be absorbed by the solar cell, but the difference in energy is converted into heat rather than into usable electrical energy. Consequently, unless the band gap is controlled, the efficiency of the solar cell will be poor. Using layers of different materials with different band gap properties is a proven way to maximize the efficiency of solar cells.

In the semiconductor and nanomaterial industries, titanium dioxide (TiO2, commonly known as titania) is added as an ingredient to coatings. TiO2 is thought to promote the internal trapping of light by scattering (redirecting) the light reflected from the metallic electrode in the active layer and also to improve the transport of charge carriers through the active layer4.

Experimental

It has been found that many of the nanomaterial studies on these materials are being carried out using a small quantity of the sample. Hence, sampling becomes a key issue to this type of analysis. The analysis was carried out using a LAMBDA™ 1050 UV/Vis/NIR spectrometer along with 150-mm integrating sphere (PerkinElmer, Inc., Shelton, CT USA) as shown in Figure 2.

This holder (Prama Industries, Mumbai, India – Figure 3) with powder sample in is clamped on the external port of the integrating sphere. A low volume powder sample press was used.

Figure 2. LAMBDA 1050 UV/Vis/NIR System with Integrating Sphere.

Figure 3. Powder sample press with sample holder.

Figure 4. 150-mm Integrating Sphere Optical diagram.

Figure 5. UV WinLab™ Software Setup.

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The sample was run using the parameters listed in Table 1.

The entrance port of the integrating sphere is kept open to minimize the specular reflection component which can cause fringes or noise at the extreme end of the range. The spectra were recorded in absorbance vs. wavelength and % reflec-tance vs. wavelength modes.

The advantage of using a LAMBDA 1050 was to have a second sample compartment where the integrating sphere can be mounted without blocking the main sample compartment.

Results and Discussion

The resulting spectrum obtained on TiO2 is shown in Figure 6.

The spectral data recorded showed the strong cut off at 410.57 nm; where the absorbance value is minimum. The data is corroborated in the % Reflectance mode.

Calculations

Band Gap energy (e) = h*c/λ (1 & 3)

h = planks constant = 6.626 x 10-34 Joules sec

c = Speed of light = 3.0 x 108 meter/sec

λ = cut off wavelength = 410.57 x 10-9 meters

H c λ e eV

6.63E-34 3.00E+08 4.11E-07 4.84156E-19 3.025976

Where 1eV = 1.6 X 10-19 Joules (conversion factor)

Conclusion

With similar experimental conditions and accessories, band gap energy values for various powder nanomaterials can be calculated. With this, the quality of TiO2 also can be determined. Various other semiconductor nanomaterials can also be subjected to the experiment for which the example spectra from literature are given in Figure 75.

The major advantages of using the specially designed small powder sample holder are:

1. Smaller quantity powder samples can be analyzed

directly

2. Due to a specially designed hand press, powder gets

caked in the cup firmly and does not slip in to the

sphere

3. Sample quantity required is 20-30 times less than the

conventional powder sample holder

4. the press gives a very even surface to the sample to

conduct reflectance experiments

5. Minimizes the specular component of the reflection

as the sample is being exposed directly to the beam.

6. cost effective sampling device with a depth of 1.5 cm

deep and 1 cm diameter.

Figure 6. TiO2 UV/Vis spectrum obtained in this work.

Table 1. Instrumental Parameters

Wavelength Range 250-800 nm

SBW 2 nm

Data Interval 1 nm

Figure 7. UV/Vis Absorption measurements for TiO2-(X) ZnFe2O4 nanocomposites.

where X = Different molar concentration of ZnFe2O4.

X = 0.01 (dark green), 0.05 (light green), 0.1 (chocolate), 0.15 (pink), 0.20 (orange).

TiO2 Hydrolysis (blue), Pure TiO2 (violet).

Workshops, Tradeshows and other events are a great way to discuss with collegues and other scoeities the wonder in this scientifici discovery. To find some powerful events that PerkinElmer is hosting or attending near you, please click here.

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References

1. Hoffman, M., Martin, S., Choi, W., & Bahnemann, D. (1995). “Environmental applications of semiconductor photo catalysis,” Chemical Review, vol. 95, pp. 69-96.

2. Wikipedia: Bandgap definition and diagram, http://en.wikipedia.org/wiki/Bandgap.

3. An Investigation of TiO2-ZnFe2O4 Nanocomposites for Visible Light Photo catalysis by Jeremy Wade, A thesis submitted to Department of Electrical Engineering; College of Engineering, University of South Florida, March 24, 2005.

4. Fundamentals of Molecular Spectroscopy; C.N. Banwell University of Sussex, 3rd edition, May 1983.

5. Wikipedia: Effect of TiO2 Nanoparticles on Polymer-Based Bulk Heterojunction Solar Cells http://jjap.ipap.jp/link?JJAP/45/L1314/,Bandgap http://www.ingentaconnect.com/content/els/02540584/2003/00000078/00000001/art00343

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Atomic Spectroscopy • AnalysisofNISTGoldNanoparticlesReferenceMaterialsUsingtheNexION

300 ICP-MS in Single Particle Mode• ColoradoSchoolofMinesUsesaNexION300QICP-MStoObtainaBetter

Understanding of the Impact of Engineered Nanomaterials

Introduction

Engineered nanomaterials (ENs) refer to the process of producing and/or controlling materials that have at least one dimension in the size range of 1 to 100 nm. They often possess different properties compared to bulk materials of the same composition, making them of great interest to a broad spectrum of industrial and commercial applications.

Recent studies have shown that some nanoparticles may be harmful to humans. A 2009 study in the Journal of Nanoparticle Research showed that zinc oxide nanoparticles were toxic to human lung cells in lab tests even at low concentrations (Weisheng et al., 2009).1 Other studies have shown that tiny silver particles (15 nanometers) killed liver and brain cells in laboratory rats. At the nano scale, particles are more chemically reactive and bioactive, allowing them to easily penetrate organs and cells (Braydich-Stolle et. al., 2005).2

ICP-Mass Spectrometry

A P P L I C A T I O N N O T E

Authors

Chady Stephan, Ph.D.

Aaron Hineman

PerkinElmer, Inc. Woodbridge, Ontario CAN

Analysis of NIST® Gold Nanoparticles Reference Materials Using the NexION 300 ICP-MS in Single Particle Mode

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To better understand the impact of nanoparticles, several key characteristics need to be assessed, such as concentration, composition, particle size, shape and other nanoparticle surface characteristics (Figure 1). Given these requirements, several analytical instruments must be used to characterize the material. Table 1 lists the key characteristics and many of the current analytical technologies that can be applied.

Figure 1. Key parameters to characterize nanomaterials (Hasselhov, 2009).3


Inductively Coupled Plasma-Mass Spectrometry ICP-MS

Single Particle ICP-MS SP-ICP-MS

Field Flow Fractionation + ICP-MS FFF-ICP-MS

Liquid Chromatography/Mass Spectrometry LC/MS

Optical Spectroscopy - UV/Vis UV/Vis


Turbidity




Confocal Microscopy




Laser-Induced Plasma Spectroscopy LIPS

Dialysis


Ultrafiltration

Centrifugation

Filtration



Laser-Induced Breakdown Detection LIBD




Molecular Gas Absorption (BET)







Fourier Transform-Infrared Spectroscopy FT-IR

FT-IR Imaging

Raman Spectroscopy TGA Coupled with Gas Chromatography/Mass Spectrometry TGA-GC/MS


Analytical Technique

Nanomaterial Characteristic

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Table 2. NexION 300 ICP-MS operational conditions.

Parameter Value

Instrument NexION 300Q ICP-MS

Nebulizer Concentric PFA-ST

Spray Chamber Baffled Cyclonic

Torch and Injector Glass Torch and Glass Injector

Power (W) 1600

Plasma Gas (L/min) 17

Aux Gas (L/min) 1

Neb Gas (L/min) 1.03

Sample Uptake Rate 0.3 (mL/min)

Sample Tubing Standard (Orange/Green)

Dwell Time 0.2 ms

Settling Time 0.05 ms

All data was collected at m/z 197, the only isotope for gold, at a 0.2 ms dwell time. The fast electronics of the system allowed a short settling time of 0.05 ms to be used, thus allowing more data to be collected for each particle. Results for 60-nm gold nanoparticles (RM 8013) are shown in Figure 2. Each peak represents the instrumental response for each integration point.

To obtain additional information from the data collected, mathematical examination of the data was necessary. Since the mathematical calculations fall outside the scope of this paper, please refer to Laborda et. al.5 Figure 3 shows the intensity distribution for RM 8011 (10 nm gold nanoparticles) with a measured median intensity of 9.01 counts.

These results can be replicated as shown by the close agreement of the three replicate dilutions in blue, red and green.

Inductively coupled plasma mass spectrometry (ICP-MS) is one of the leading analytical techniques capable of measuring and assessing many of these key characteristics of metal-containing particles.4 Low detection limits are critical in determining small concentrations of particles in a liquid as well as examining the characteristics of a single particle. Additionally, flexibility of the parameters, such as dwell time and speed of the electronics, can influence the quality of data collected. This work explores the capability of modern ICP-MS to measure the key characteristics of metal manufactured nanoparticles.

Experimental

All work was performed using a NexION® 300 ICP-MS (PerkinElmer, Shelton, CT, U.S.). In Standard mode, composition and concentration measurements were collected. Single Particle mode analysis (SP-ICP-MS) allows the differentiation between soluble and nanoparticles analyte signal, measuring nanoparticles size (if shape is known or assumed) and assessing agglomeration and/or size distribution. Coupled to a size-separation technique (i.e. field flow fractionation [FFF] and liquid chromatography [LC]), ICP-MS is capable of addressing size, size distribution, surface charge and surface functionality.

The NexION 300 ICP-MS is equipped with a high-speed mass analyzer which has a scan rate that exceeds 5000 data points/sec, a read speed that exceeds 3000 points/sec, a slew speed of 1.6 million amu/sec, and a detector capable of integrating ionic signals at a dwell time as short as 100 µs with a settling time of only 50 µs. Combined with a unique ion path design (Triple Cone Interface [TCI] and Quadrupole Ion Deflector [QID]), the NexION 300 ICP-MS, in SP-ICP-MS mode, is crucial in assessing nanoparticle fate, transformation and transportation in different matrices (i.e. environmental, biological, food, etc.).

All samples were measured in triplicate (three separate dilutions) under the conditions stated in Table 2.

Gold nanoparticle standard reference materials (RM 8011, RM 8012 and RM 8013 – NIST®, Gaithersburg, MD, U.S.) were used to represent samples.

The gold particles were suspended in a solution of deionized water at a concentration of 2 x 105 particles/mL. In order to avoid dissolution of the gold nanoparticles, acid was not added.

Figure 2. General pattern of obtained signal when measuring nanoparticles in Single Particle-ICP-MS mode.

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The intensity of the pulses generated by a single nanoparticle is a function of the number of atoms in the nanoparticle, and hence its size. The plot of the median intensity, calculated at P(x) = 0.5 versus the nanoparticle diameter of the NIST® standards, is shown in Figure 7 (Page 5).

Nanoparticle diameter limit of detection (LOD) was related to the capability of a nanoparticle to produce a pulse with a number of counts equal to three times the standard deviation of the background. This limit of detection depends on the transmission efficiency of the ion plume generated from each nanoparticle through the spectrometer. Under the operational conditions stated in Table 2 (0.2 ms dwell time and 0.05 ms settling time), a detection limit of 2.56 nm of gold nanoparticle was obtained.

Similarly, Figure 4 shows the intensity distribution for RM 8012 (30 nm gold nanoparticles) with a measured median intensity of 20.02 counts. The median intensity indicates the size of the particle and will be shown later as a way to calibrate this determination.

Figure 5 shows the intensity distribution for RM 8013 (60 nm gold nanoparticles) with a measured median intensity of 42.18 counts. A second small peak is seen in this figure and can be attributed to two particles being introduced into the plasma at the same time.

By applying a cumulative distribution function to the analyzed RMs, we can plot the cumulative distribution vs. counts of the different RMs analyzed to obtain the plots shown in Figure 6. The cumulative distribution function describes the probability that a real-valued random variable x with a given probability distribution f(t) will be found at a value less than or equal to x and is defined by the following equation:

4

Figure 3. Cumulative statistics – events vs. counts – for SRM 8011 (10 nm gold nanoparticles).



Figure 6. Cumulative distribution vs. counts of the various NIST® SRMs (8011, 8012, 8013) gold nanoparticles.

RM 8011 – 10 nm GNP

RM 8012 – 30 nm GNP

Au 197, counts

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References

1. Weisheng Lin, Yi Xu, Chuan-Chin Huang, Yinfa Ma, Katie B. Shannon, Da-Ren Chen and Yue-Wern Huang, “Toxicity of nano- and micro-sized ZnO particles in human lung epithelial cells”, Journal of Nanoparticle Research, 2009, Volume 11, Number 1, pp 25-39.

2. Laura Braydich-Stolle, Saber Hussain, John J. Schlager and Marie-Claude Hofmann, “In Vitro Cytotoxicity of Nanoparticles in Mammalian Germline Stem Cells”, Toxicological Sciences, 2005, Volume 88, Issue 2, pp 412-419.

3. Hasselhov, M., Kaegl, R., “Analysis and Characterization of Manufactured Nanomaterials in Aquatic Environment”, Chapter 6 of Environmental and Human Health Impacts of Nanomaterials, Eds. Lead, J. and Smith, E,. Blackwell Publishing Ltd.

4. Salamon, A.W. and et. al., “Nanotechnology and Engineering Nanoparticles – A Primer”, PerkinElmer, 2010.

5. Francisco Laborda, Javier Jiménez-Lamana, Eduardo Bolea and Juan R. Castillo, “Selective identification, characterization and determination of dissolved silver(I) and silver nanoparticles based on single particle detection by inductively coupled plasma mass spectrometry”, Journal of Analytical Atomic Spectrometry, 2011, Volume 26, Issue 7, pp 1362-1371.

6. E.M. Heithmar and S.A. Pergantis“Characterizing Concentrations and Size Distributions of Metal-Containing Nanoparticles in Waste Water (APM 272)”, U.S. Environ-mental Protection Agency, Office of Research and Development, Washington, DC 20460.

Conclusion

ICP-MS is rapidly becoming the elemental measurement technique of choice for assessing the manufacturing and environmental life cycle of engineered nanoparticles. In Standard mode, an ICP-MS provides accurate composition and concentration measurements. In Single Particle mode (SP-ICP-MS), it allows the differentiation between ionic and particulate signals, measures particle sizes (if shape is known), and explores agglomeration and size distribution. Modern instruments, with ultra-fast electronics that enable the fastest data rates to capture nanoscale events, can provide advantages in the collection of more data per unit of time, with greater precision. This data is important in characterizing nanoparticles used in food and consumer products. Additionally, SP-ICP-MS is growing into the analytical technique of choice used in exploring the fate, transformation and effects of manufactured nanomaterials in the environment.6

Figure 7. Median intensity counts vs. NIST® RMs nanoparticle diameter.




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Colorado School of Mines Uses a NexION 300Q ICP-MS to Obtain a Better Understanding of the Environmental Impact of Engineered Nanomaterials

There is an unprecedented amount of scientific research going on today dedicated to the study of a world so small, we cannot see it even with a conventional microscope. That world is the field of nanotechnology – the realm of atoms and nanostructures. But what actually is nanotechnology? The National Nanotechnology Initiative (NNI) defines nanotechnology as the study of materials with dimensions <100 nm, where unique properties enable novel applications to be carried out. For example, gases, liquids, and

solids can exhibit unusual physical, chemical, and biological properties at the nanoscale level, differing in critical ways from the properties of the bulk materials. Nanomaterials occur in nature, such as clay minerals and humic acids, but they can also be produced by human activity such as diesel emissions, or welding fumes. In addition, nanomaterials

Case study


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can be specifically engineered to exhibit unique optical, electrical, physical, or chemical characteristics. Depending on their chemical and physical characteristics, these engineered nanomaterials (ENMs) can be made to exhibit greater physical strength, enhanced magnetic properties, better conduction of heat or electricity, greater chemical reactivity, or improved optical properties.

Engineered Nanomaterials

Most ENMs can be divided into two main categories - carbon-based, such as nanotubes, which are used to improve material strength, or metal-containing ones such as silver (Ag), gold (Au), or titanium (Ti) nanoparticles (NP), which are incorporated into a product matrix like a solar cell. For these applications, the ENMs are typically bound to the matrix of the material, and as a result, are less likely to be released into the environment. However, many of the metal-containing ENMs are used in dispersive applications where they are intentionally released from the product. For example, fabrics containing silver nanoparticles used to kill bacteria release silver at varying rates during the washing cycle, depending on the type of fabric and the washing conditions. It is therefore clear that the use of ENMs in consumer, industrial, and healthcare products is growing rapidly, with an estimated 1000 commercially-available products being used today for many diverse and varied applications.

Environmental Impact

The unique properties of ENMs have also created intense interest in the environmental behavior of these materials. Due to the increase in use of nanotechnology-based products, nanoparticles are more likely to enter the environment. Different ENPs will have different properties and will therefore behave very differently when they enter the environment. So in order to ensure the continued development of nanotechnology products, there is clearly a need to evaluate the risks posed by these engineered nanoparticles, which will require proper tools to carry out exposure assessment studies to better understand how they interact with soil, sediment, and water systems.

Colorado School of Mines

One of the leading academic research groups involved with the study of the impact of ENPs on the environment is the Colorado School of Mines (CSM), based in Golden, Colorado. Founded in 1874, two years before Colorado officially became a state, Mines’ early academic programs primarily focused on geology, mineralogy, mining engineering and metallurgy, with an emphasis on gold and silver and the assaying of these minerals. As the institution grew, it has expanded its role to focus specifically on understanding the Earth, harnessing

energy and sustaining the environment. Today, CSM has achieved global recognition by developing a curriculum and research program geared towards responsible stewardship of the Earth and its resources.

Characterization of Engineered Nanoparticles

The major research into nanoparticles at CSM is being carried out by Dr. James Ranville, an associate professor in the Department of Chemistry and Geochemistry. Under his guidance, Dr. Ranville’s laboratory is focused primarily on environmental geochemistry, with a particular emphasis on carrying out research into the characterization of nanoparticles in various environmental processes. Some of his other studies include an understanding of arsenic and uranium contamination in ground waters, and the aquatic toxicity of cadmium (Cd), copper (Cu), and zinc (Zn) in streams impacted by the mining industry.

Current analytical approaches to assess the impact of nanoparticles on the environment include a combination of computer modeling to predict life cycles and direct analytical measurement techniques. Prediction of environmental concentrations of ENPs through modeling is based on knowledge of how they are emitted into the environment, together with their eventual fate and behavior, which requires validation through measurement of actual environmental concentrations. For ENPs that are only recently being introduced into the environment, extremely sensitive methods are required. Although the direct measurement approach is not hampered by the underlying assumptions of exposure modeling, it is very important to assure that direct observations are representative in time and space for the regional setting in which the observation was made. This was emphasized by Dr. Ranville when he explained,

“ENPs differ from most conventional dissolved chemicals in terms of their heterogeneous distributions. Therefore, when it comes to environmental health studies (EHS), it is not only important to determine their concentrations, but also other metrics like shape, size distribution, and chemical composition, which require extremely sophisticated techniques.”

Many analytical techniques are available for nanometrology, only some of which can be successfully applied to nano-EHS studies. Traditional methods for assessing particle concentration and particle size distributions include: electron microscopy, chromatography, field flow fractionation, centrifugation, laser light scattering, ultrafiltration and UV spectroscopy. Difficulties generally arise due to a lack of sensitivity for characterizing and quantifying particles

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at environmentally relevant concentrations (low µg/L). Furthermore, the lack of specificity of these techniques is problematic for complex environmental matrices that may contain natural NPs having polydispersed particle distributions, as well as having heterogeneous compositions.

Role of ICP-MS

An integral part of Dr. Ranville’s research in the area of nanoparticle sensitivity and specificity has involved the use of ICP mass spectrometry (ICP-MS). Because of its trace element capability, and extremely low detection limits, the technique is ideally suited to the characterization of ENPs, containing elements such as Ag, Au, Ti and Fe, which have been integrated into larger products such as consumer goods, foods, pesticides, pharmaceuticals, and personal care products. The ubiquitous use of goods containing these nanomaterials will inevitably lead to environmental releases, which may be studied and quantified using state-of-the-art ICP-MS technology, such as PerkinElmer’s NexION® 300Q system, which Dr. Ranville’s lab acquired recently.

Single Particle ICP-MS Studies

One area in particular that his team is focusing on is single particle (SP) ICP-MS, which is a novel technique for detecting and sizing metallic nanoparticles at environmentally relevant concentrations. While this method is still in its infancy, it has shown a great deal of promise in several applications, including determining concentrations of silver nanoparticles in complex matrices, such as wastewater effluent. The method

involves introducing NP-containing samples, at very dilute concentration, into the ICP-MS and collecting time-resolved data. Very short integration times on the order of 5-10 ms are used in order to detect individual particles as pulses of ions after they are ionized by the plasma. Observed pulse number is related to the nanoparticle concentration by the nebulization efficiency and the total number of NPs in the sample, while the mass, and thus the size of the NP is related to the pulse intensity. The principles of characterizing nanoparticles using SP-ICP-MS are shown in Figure 2.

In this example, nano-Ag imbedded in athletic socks, which is used as a bactericide, has been shown to release during simulated wash cycles.1 By collecting and analyzing a simple aqueous solution with the NexION 300Q ICP-MS,2 and collecting data using the SP-ICP-MS technique,3 the size, concentration, and associated dissolved material can be quantified – all important parameters in environmental and biological modeling. Once the raw data is collected, the dissolved content is at low signal intensity, with nanoparticles creating pulses above this background where the height of the pulse relates to the mass of analyte and the number of pulses correlates to the concentration of NP in the samples. The size distribution of particles in the sample can be calculated using well-understood SP-ICP-MS theory.4 A histogram of nanoparticle diameter versus number of events (NP number) can then be created in order to visualize the NP distribution in the sample, in addition to calculating the concentration of both NP and dissolved fractions of the NP released from the products.5 In this way, scientists can have a better understanding of how nanomaterials will behave in the environment at realistic concentrations.

Figure 1. Dr. Jim Ranville (far left) and his graduate students (left to right): Rob Reed, Denise Mitrano, Val Stucker, Evan Gray; and sitting on top of the NexION 300Q is Jerry the Plasma Squirrel.

Figure 2. Principles of characterizing nanoparticles using single particle ICP-MS analysis with the NexION 300Q system.

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Optimized Measurement Protocol

However, it should be emphasized that for this approach to work effectively at low concentrations, the speed of data acquisition and the response time of the ICP-MS detector must be fast enough to capture the time-resolved nanoparticles pulses, which typically last only a few milliseconds or less. This is emphasized in Figure 3, which shows a real-world example of the time-resolved analysis of 30 nm gold particles using the NexION 300 ICP-MS. It can be seen that the gold nanoparticle has been fully resolved and characterized with 3-4 data points in <1 millisecond, showing the benefit of very fast data acquisition rate and short dwell times of the NexION 300 system for this kind of work.

Dr. Ranville and his team have published a number of papers and articles on this very exciting area of research, some of which are referenced at the end of this article. His PhD students play a very important role on the diverse range of nanoparticle studies they have carried out. Of particular mention is Denise Mitrano, who is examining NPs in wastewaters, the likely major route of environmental exposure to NPs released from consumer products. Rob Reed is looking at the release of NPs from various types of products, including the release of carbon nanotubes, which can be analyzed by ICP-MS due to the residual catalysis metals present in the tubes. And Evan Gray is examining tissues to determine the potential for bioaccumulation of NPs.

Dr. Ranville has been a long-time user of PerkinElmer equipment over the years ever since he joined the CSM faculty in 1994. That year, he acquired an Optima™ 3000 ICP-OES, which was followed by an ELAN® 6000 ICP-MS in 2001 and an Optima 5300 ICP-OES in 2004. The

department’s trace element capabilities got an upgrade last year when they acquired a NexION 300Q ICP-MS. Dr. Ranville summed up his impressions of the instrument when he commented:

“The NexION 300Q ICP-MS gives us extended capabilities for nanoparticle analysis. As we work with PerkinElmer to develop new ways to detect and quantify nanomaterials, the flexibility of the data acquisition measurement protocol allows us to collect transient data with a very short duty cycle, which will be a major improvement over our existing technology for single particle ICP-MS studies. This is a very significant development for nanometrology, particularly as we move forward into multielement characterization.”

There is no question that Dr. Ranville’s work is on the cutting edge of what can be achieved with an ICP-MS system. We are honored that they chose the NexION technology for this extremely complex analysis. We are also very hopeful that they will continue to publish their work, as it’s very important to have a better understanding of how engineered nanoparticles, particularly those used in consumer product applications, interact with the environment. If they continue to push these boundaries and generate high-quality data, it is only a matter of time before single particle ICP-MS becomes a routine analytical technique.

We’d like to conclude by quoting from CSM’s mission statement web page, which clearly encompasses Dr. Ranville’s work:

“Mines’ well-defined and focused mission is achieved by the creation, integration and exchange of knowledge in engineering, the natural sciences, the social sciences, the humanities, business, and their union, to create processes and products to enhance the quality of life of the world’s inhabitants. Mines is consequently committed to serving the people of Colorado, the nation, and the global community by promoting stewardship of the Earth, advancements in energy and sustaining the environment.”

There is no doubt that the work being carried out by Dr. James Ranville and his team at the Department of Chemistry and Geochemistry fully embraces the School’s mission by making the environment a safer place. We are so happy that PerkinElmer and the NexION 300Q ICP-MS are helping them achieve that goal.

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Figure 3. Time-resolved analysis of 30 nm gold nanoparticles using the NexION ICP-MS, showing the pulse is fully characterized in less than 1 ms.

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Further Reading

• TheNationalNanotechnologyInitiative(NNI):http://www.nano.gov/

• AnOverviewoftheCapabilitiesofField-Flow-FractionationCoupled with ICP-MS to Separate, Detect and Quantitate Engineered Nanoparticles: J. Ranville, K. Neubauer, R. Thomas; submitted to and accepted by Spectroscopy Magazine, publication date, Summer, 2012.

• AnIntroductiontoFlowFieldFlowFractionationandCoupling to ICP-MS: J. Ranville, D. Mitrano. K. Neubauer; PerkinElmer, Inc. White Paper.

• DeterminingTransportEfficiencyforthePurposeofCounting and Sizing Nanoparticles via Single Particle Inductively Coupled Plasma Mass Spectrometry: H.E. Pace, J. Rogers, C. Jarolimek, V.A. Coleman, C.P. Higgins, and J.F. Ranville; Analytical Chemistry, 83 (24), pp 9361–9369, (2011).

• DetectionofNanoparticulateSilverUsingSingleParticleInductively Coupled Plasma Mass Spectrometry: D.M. Mitrano, E.K. Leshner, A. Bednar, J. Monserud, C.P. Higgins, and J.F. Ranville; Environmental Toxicology and Chemistry, Vol. 31, No. 1, pp. 115–121, (2012).

• SilverNanoparticleCharacterizationUsingSingleParticleICP-MS (SP-ICP-MS) and Asymmetrical Flow Field Flow Fractionation ICP-MS: D.M. Mitrano, A. Barber, A. Bednar, P. Westerhoff, C.P. Higgins, and J.F. Ranville; Journal of Analytical Atomic Spectrometry, 27, 1131-1142, (2012).

• OvercomingChallengesinAnalysisofPolydisperseMetal-containing Nanoparticles by Single Particle Inductively Coupled Plasma Mass Spectrometry: R.B. Reed, C.P. Higgins, P. Westerhoff, S. Tadjiki, J.F. Ranville; submitted and accepted by Journal of Analytical Atomic Spectrometry, 27, 1093-1100, (2012).

To see how our customers are making a difference, visit www.perkinelmer.com/envirostories

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Check out our Spotlight on Application e-zine, a quaterly compendium of our most recent analytical applications, delivering a variety of topics which address the pressing issues and analytical challenges you may face.

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Hyphenated Techniques

• Characterizing Interaction of Nanoparticles with Organic Pollutants Using coupling Thermal Analysis with Spectroscopic Techniques

• An Introduction to Flow Field Flow Fractionation and Coupling to ICP-MS • Coupling Flow Field Flow Fractionation to ICP-MS for the Detection and

Characterization of Silver Nanoparticles

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Whitepaper Inductively Coupled Plasma – Mass Spectrometry

AuthorsDenise Mitrano James F. Ranville

Department of Chemistry and Geochemistry Colorado School of Mines Golden, CO USA

Kenneth Neubauer Senior Scientist – ICP-MS Technology


Introduction

Inductively coupled plasma-mass spectrometry (ICP-MS) is the method of choice for analysis of most elements across the periodic chart. Its multi-element capability, low detection limit (ppt), and wide dynamic range (109 orders of magnitude) also make it ideal for

the measurement of inorganic engineered nanoparticles (ENPs). While ICP-MS can be used directly to obtain concentrations of nanoparticulate-associated elements, more information on characteristics of ENPs can be obtained by first separating the particles by size prior to ICP-MS analysis. The most versatile size-separation technique is field flow fractionation (FFF). By introducing size-fractionated material into the ICP-MS, the size and elemental composition of complex, polydisperse and chemically heterogeneous ENPs can be determined. Furthermore, the similar flow conditions required by both ICP-MS and FFF make interfacing relatively simple.

Field Flow Fractionation

Field flow fractionation (FFF) consists of a suite of high-resolution elution techniques which can size separate nanoparticles in the 1-100 nm range and colloids up to 1 micron. By use of either FFF theory or calibration with size standards, the technique can be utilized to determine particle size. The separation process is similar to chromatography except that the separation is based on physical forces as opposed to chemical interactions.

An Introduction to Flow Field Flow Fractionation and Coupling to ICP-MS

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1. Mansfield, E., Kar, A., Hooker, S.A., Applications of TGA in Quality control of SWCNTs, Analytical and Bioanalytical Chemistry, Vol. 369, Number 3, 1071-1077. 2009.

2. Ozin, G.A., Arsenault, A.C., and Cademartiri, L., Nano-chemistry – A Chemical Approach to Nanomaterials, Royal Society of Chemistry, Cambridge, U.K., 2009. Page 209.

3. National Nanotechnology Initiative – Human Health Workshop, November 2009, Washington D.C., US.

4. Wikipedia, Carbon Nanotubes, Nov. 2010, http://en.wikipedia.org/wiki/Carbon_nanotube#Structural

5. Pang L.S.K., Saxby, J.D., and Chatfield, S.P., Thermo-gravimetric Analysis of Carbon Nanotubes and Nano-particles, J. Physical Chemistry, 97, 27, 1993.

6. Saxby, J.D., Chatfield, S.P., et al, Thermogravimetric analysis of Buckminsterfullernce and Related Materials in Air, J. Phys. Chem. 1992, 96,17-18.

7. Joshi, A., Nimmagadda, R., and Herrington, J., Oxidation Kinetics of Diamond, Graphite and Chemical Vapor Deposited Diamond Films by Thermal Gravimetry, J. Vac. Sci. Technol. A 8(3), May/June, 1990.

Additional Reading

PerkinElmer, Nanotechnology and Engineered Nanomaterials – A Primer, www.perkinelmer.com/nano

PerkinElmer, Nanomaterials Reference Library www.perkinelmer.com/nano

Acknowledgement

Special thanks to E. Sahle-Demessie and A. Zhao of the U.S. EPA, January 2011, for providing the TGA data. This thermo-gravimetric data is from an on-going study of environmental effects on carbon nanotubes.

Summary

Based on the Pyris 1 TGA data collected, UV light has an effect on CNTs. As this study suggests, the longer the CNTs are subjected to UV light, the sooner CNTs decompose when heated to elevated temperatures.

Further investigation

Because this is early in an entire series of CNT analytical experiments, there are more TGA tests to conduct. It is suggested that a series of isothermal tests be conducted next. They should involve longer UV exposures and similar exposures to this experiment. Based on the scanning data provided, it is suggested that isothermal tests be conducted at 500 ˚C, 550 ˚C, 600 ˚C, and 650 ˚C. These future isothermal tests would help define the test protocol needed to examine CNTs found in water, soils, or air.

Conclusion

Thermogravimetry by the Pyris 1 TGA is a simple analytical technique that is frequently used to characterize carbon nanotubes. The Pyris 1 TGA delivers accurate results quickly because of its low mass furnace. The Pyris 1 TGA low mass furnace has accurate temperature control and fast cooling for higher sample throughput.




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Introduction

Analysis of nanomaterials should include characterization of composition as well as size. Many techniques are capable of sizing nano-size particles, such as dynamic light scattering (DLS), UV/Vis spectrophotometry, and transmission electron microscopy (TEM), yet provide no information on the composition of the particle and/or are time intensive and costly. Inductively coupled plasma-mass spectrometry (ICP-MS), however, is a standard instrument in many analytical laboratories and is the method of choice for analysis of most elements across the periodic chart. The multi-element capability of the ICP-MS, low detection limit (ppt),

and wide dynamic range (109 orders of magnitude) also make it ideal for application to the measurement of inorganic engineered nanoparticles (ENPs). While ICP-MS can be used directly to obtain concentrations of nanoparticulate-associated elements, more information on characteristics of ENPs can be obtained by coupling a size-separation step prior to ICP-MS analysis. The most versatile size-separation technique for this application is field flow fractionation (FFF). Although FFF is a powerful nanoparticle sizing technique, many common detectors used in conjunction with FFF do not provide the needed compositional information of the particles. Therefore, the resultant hyphenated technique of FFF-ICP-MS provides nanoparticle sizing, detection, and composition analysis capabilities at the parts per billion (ppb) level, which is critical to environmental investigations of nanomaterials. Furthermore, the similar flow conditions required by both ICP-MS and FFF make interfacing relatively simple.



Authors

Denise Mitrano James F. Ranville

Department of Chemistry and Geochemistry Colorado School of Mines Golden, CO USA

Kenneth Neubauer Senior Scientist – ICP-MS Technology


Coupling Flow Field Flow Fractionation to ICP-MS for the Detection and Characterization of Silver Nanoparticles

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Experimental

Materials

Silver nanoparticles of 20 and 40 nm (Nanocomposix, San Diego, CA, USA) were acquired in stock suspensions at a nominal concentration of 20 mg Ag/L and were stabilized in aqueous 2 mM citrate, per the manufacturer. Nano-Ag suspensions were made by diluting the stock solutions with 18.2 M-ohm Nanopure water to final concentrations, ranging from 10 to 500 μg/L. Aqueous Ag standards (High-Purity Standards, Charleston, SC, USA), used for calibration, were diluted in 1% nitric acid (Optima grade) to concentrations ranging from 1 to 100 μg/L.

Red mercaptoundecanoic acid (MUA)-coated CdSe/ZnS quantum dots (NN-Labs, Fayettville, AR, USA) were investigated in the second study where the hydrodynamic diameter was 25 nm, with a metal core stated as 5 nm. Stock solutions were diluted approximately 1000-fold, using deionized water to concentrations ranging from 4.6 x 1013 to 1.8 x 1016 particles/L.

Instrumentation

An ELAN® 6100 ICP-MS (PerkinElmer, Shelton, CT, USA) was used for all analyses. Standard operating and tuning procedures were used. Only one silver isotope was monitored (107Ag) with a dwell time of 2000 ms, alternating with a Bi internal standard with a dwell time of 1000 ms, resulting in a data point being collected at a rate of approximately one every three seconds. The total number of readings per sample was chosen such that the data were collected for the entire length of the fractogram, which, depending on experimental conditions, ranged from 40 to 60 minutes.

An AF2000 asymmetrical FFF instrument (Postnova Analytics, Salt Lake City, UT, USA) was used for the silver experiments. A 10 kDa regenerated cellulose membrane was used and was replaced approximately every 25 runs. The carrier fluid consisted of 0.01% FL-70 surfactant and 0.025% sodium azide (an antibacterial agent). The FFF instrument was directly plumbed into the ICP-MS. The channel flow conditions allowed direct connection of the FFF effluent to the ICP-MS nebulizer without a flow splitter. Asymmetrical flow field flow fractionation (AF4) runs were programmed to start with a 10 min relaxation period (focusing step), followed by 40 min elution (0.7 mL/min cross flow and 1.0 mL/min detector flow) with 10 min flush (field-off) between each experimental run. The detector flow can be diverted to a number of instruments, such as ICP-MS, for characterization after AF4 separation. The carrier fluid used to flush the channel after analysis is typically also analyzed in order to determine the unfractionated portion of analyte. Details of AF4 and ICP-MS run conditions are given in Tables 1 and 2 (Page 3).

Nanometrology

Nanotechnology has great potential in both industrial and commercial sectors, producing useful products for society either when used alone or when integrated with other material into products (e.g. consumer goods, foods, pesticides, pharmaceuticals, and personal care products, among others). Nanotechnology, defined as the control of matter between 1 and 100 nm where unique phenomena occur because of their small size, has seen great innovation and study in recent years.

Several classes of ENPs contain metals that make them particularly suitable for characterization by ICP-MS methods. For example, quantum dots (QDs) often contain cadmium (Cd), selenium (Se), tellurium (Te) and zinc (Zn), among others. QDs are the smallest ENPs having semiconductor properties and are investigated for their use in transistors, solar cells, and LEDs.

Despite rapid development, early public acceptance, and acknowledgement of probable release of nanoproducts to the environment, the potential for adverse environmental effects has not yet been established. In the case of QDs, most of the constituent elements can be toxic to organisms.

This knowledge gap exists, in part, because of the innate difficulties of detection, characterization, and quantification of ENPs, particularly in environmental and biological samples. There are universal calls for improvements in nanometrology. Many techniques are capable of sizing nano-sized particles (nanoparticles and quantum dots) in simple laboratory systems, including dynamic light scattering (DLS), transmission electron microscopy (TEM), and disc centrifugation (DCS), among others. Yet these methods provide little or no infor-mation on the composition of the particle. These techniques are also often not sensitive enough to work at environmentally or biologically relevant concentrations (sub-μg/L). Finally, these techniques lack specificity, which means they are not able to distinguish ENPs from other matrix constituents, such as natural particles, humic substances, and cellular debris. Coupling FFF with ICP-MS (or ICP-OES/AES), however, garners element-specific information at trace concentration levels1 when studying metal-containing NPs.2 Furthermore, the capability of multi-metal analysis is an added benefit when coupling FFF with mass spectrometry.

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Size characterization of quantum dot samples was accom-plished by an F1000 symmetrical FFF instrument (Postnova Analytics) equipped with 1 kDa regenerated cellulose membrane. The ICP-MS (ELAN 6100, PerkinElmer) was used to measure the concentrations of 64Zn, 114Cd, and 82Se, with 209Bi as the internal standard. Carrier fluid also consisted of 0.01% FL-70 and 0.1 mM sodium azide. Pumps delivered the carrier fluid at a channel flow rate of 1.0 mL/min and recirculated the cross flow at a rate of 0.9 mL/min. A 20 μL injection loop was used for sample injection.

The outlet flow from the FFF passed through a fluorescence detector and then to the ICP-MS. Details of FFF and ICP-MS run conditions are shown in Tables 1 and 2. An example of the online addition of fluorescence and ICP-MS detectors is given in Figure 1. More details on FFF theory, instrumental setup, and coupling to various detectors can be found in PerkinElmer white paper “An Introduction to Flow Field Flow Fractionation and Coupling to ICP-MS”.

Table 1. FFF Parameters.

CdSe / Zn Parameter Ag Nanoparticles Quantum Dots

Instrument Postnova AF2000 Postnova F1000 (asymmetrical) (symmetrical)

Channel Size 355 x 60 x 40 mm 20 x 270 mm

Membrane Type Regenerated Cellulose

Membrane Porosity 10 kDalton 1 kDalton

Spacer Width 500 µm 254 µm

Sample Injection Volume 100 µL 20 µL

Detector Flow 1 mL/min

Cross Flow 0.7 mL/min 0.9 mL/min

Injection Delay 1 min 15 sec

Equilibration Time 10 min 2 min

Flush Time 10 min N/A

Carrier Fluid 0.1% FL-70, 0.01% FL-70, 0.025% NaN3 1 mM NaN3

Figure 1. Schematic of AF4-ICP-MS analysis with online addition of UV/Vis analysis.

Table 2. ICP-MS Parameters.

CdSe / Zn Parameter Ag Nanoparticles Quantum Dots

Instrument PerkinElmer ELAN 6100 ICP-MS

Nebulizer Cross Flow

Spray Chamber Scott Double Pass

Neb Gas Flow Optimized for <3% Oxides

Sample Flow 1 mL/min

RF Power 1000-1300W

Dwell Time 3000 ms 4000 ms

Analytes Ag107; Bi109 Zn66; Cd111; Se82; Bi209

Total Analysis Time 60 min 30 min

Daily Standards

For the silver nanoparticle study, to ensure the reproducibility of results from day to day, a daily standard was prepared for AF4-ICP-MS analysis that consisted of a mixture of 20 and 40 nm Ag nanoparticles at 100 μg/L each. This sample was run at the beginning and end of each day, determining if there was a shift in retention time of the particles or change in ICP-MS response (percent recovery). If the retention times did not drift over the course of the day for the standard mixture, we presumed that sample runs were not affected by matrix/membrane or particle/membrane interactions throughout the day.

Although size can be directly computed from retention time using FFF theory, for this study we made a linear plot of particle size versus retention time. The linear equation from this plot could then be applied to sample runs to convert elution time to particle diameter.

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It was proposed, but not confirmed, that the excess Cd was associated with the MUA coating as part of an incomplete washing process during manufacturing. This additional Cd demonstrated much higher than expected toxicity. The symmetrical flow FFF-ICP-MS characterization proved integral in demonstrating that Cd was, at least initially, integral to the quantum dot and not simply excess Cd in solution (Figure 3). This element-specific information would be difficult, if not impossible, to acquire using chemical analysis approaches.

Conclusions

Concerning engineered nanoparticles, nanometrology is a growing field that is certain to benefit from on-line flow FFF-ICP-MS analysis. The combination of continuous fractionation using FFF, with the sensitive, multi-elemental capability of ICP-MS, will provide increased knowledge about size-dependent variations in composition and trace element interactions at environmentally and biologically relevant concentrations. Although method development can at times be a lengthy process, the multitude of run conditions, such as flow rates, carrier fluid composition, as well as membrane type and porosity, lends itself to the flexibility needed to fractionate a variety of particles under a number of conditions. The universality of this will undoubtedly soon make flow FFF-ICP-MS an integral part of the standard methods with which to study nanoproducts in this fast growing field.

Analytical Results

Resolution and detection limit

There are a number of parameters in the AF4 method that contribute to both detection limit and resolution, the most important of which is the cross flow parameter of the FFF. Under the flow conditions used, we see nearly baseline separation between the 20 nm and 40 nm Ag nanoparticles (Figure 2), with the void peak (unresolvable material) present on the far left of the fractogram. An increase in cross flow would allow better separation for smaller particles, down to as small as 3-5 nm. However, with increasing cross flow, the analysis time increases and there is a higher chance of particle/membrane interaction, which leads to a decrease in recovery. Therefore, a balance needs to be struck to achieve the best results when considering these multiple factors. Based on the data for 25 and 100 ppb Ag, the detection limit under the current run conditions is estimated to be approximately 5 ppb. The concentration detection limit was determined by running serial dilutions through the FFF-ICP-MS until no discernable analyte peaks were detected above the background.

Mixed Metal Analysis with Flow FFF-ICP-MS

The results for the symmetrical flow FFF-ICP-MS characterization of a commercial CdSe/ZnS/MUA quantum dot is shown in Figure 3. Here, it is demonstrated that the manufacturer incorrectly described some quantum dot characteristics, specifically the metal content in the dots.4 It was found that the MUA coated quantum dots had a significantly higher (9:1) Cd:Se ratio than the expected nearly 1:1 molar ratio.

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Figure 2. Analysis of 25 and 100 ppb nano-Ag mixture.3

Figure 3. Symmetrical FFF-ICP-MS fractogram of red-emitting MUA coated CdSe/ZnS quantum dots (QDs). The first small peak is the void peak, which contains unfractionated materials. The larger analyte peak shows that all three metal signals are associated with the fluorescent signal (FL) from the QD. The particle size at the peak maximum was calculated to be 23 nm.4

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Thanks to Dr. Anthony Bednar and the U.S. Army Corps of Engineers, who, through grant number W912HZ-09-P-1063, makes a portion of this research possible.

References

1. Dubascoux S., HÈcho I., Hassellˆv M., Kammer F., Gautier M., Lespes G. Field-flow fractionation and inductively coupled plasma mass spectrometer coupling: History, development and applications. Journal of Analytical Atomic Spectrometry 25:613-623.

2. Gimbert L., Andrew K., Haygarth P., Worsfold P. 2003. Environmental applications of flow field-flow fractionation (FIFFF). TrAC Trends in Analytical Chemistry 22:615-633.

3. Mitrano D.M. 2011. Unpublished Data.

4. Pace H.E., Lesher E.K., Ranville J.F. Influence of stability on the acute toxicity of CdSe/ZnS nanocrystals to Daphnia magna. Environmental toxicology and Chemistry 29:1338-1344.

5. PerkinElmer Corp., PerkinElmer Nanomaterials Reference Library, accessed 12/15/2011, www.perkinelmer.com/nano.




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Introduction

There are more than a thousand products claiming to contain Engineered Nanoparticles (ENP) in products ranging from clothing, cosmetics, and electronics, to biomedical, chemical, energy, environmental, food, materials and optical products. The effects of ENP on environmental and human health are strongly related to their large surface-to-mass ratio and surface properties. Although the influence of natural colloids on the environment is well documented, we have limited understanding of the fate, transport, toxicity and pollutant interactions of ENP. The tools to study these interactions are being developed.

Pollutants-colloid interaction

Many nanoparticles suspended in natural water come in contact with pollutants and proteinaceous materials. The unique properties and behaviors of ENP are strongly influenced by their physical-chemical characteristics, including their high surface area relative to their volume, high interface energy and high surface-to-charge ratio density.

The partitioning and phase distribution of hazardous organic compounds (HOC) can influence the fate and bioavailability of the contaminants in aquatic systems and aquatic microorganisms significantly. There are a wide range of organic and inorganic pollutants that become associated with partitioning of HOC to the particles. This partitioning has been shown to be inversely proportional to log solubility of HOC and the log of particle concentration. Dynamics of nanoparticle-water partitioning can significantly influence the speciation, and hence, understanding the fate, transport and toxicological impact of POPs such as PAHs, PCBs is critical. The fate of organic pollutants in aquatic environment depends largely on their partitioning behavior to nanoparticles and colloids.

TGA-GC-MS

A P P L I C A T I O N N O T E

Authors

E. Sahle-Demessie Amy Zhao

U.S. Environmental Protection Agency Cincinnati, OH USA

Andrew W. Salamon


Characterizing Interaction of Nanoparticles with Organic Pollutants Using Coupling Thermal Analysis with Spectroscopic Techniques

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The physio-chemical properties relating to the environmental behavior of hydrophobic organic compounds are mainly affected by the aqueous solubility and octanol-water partition coefficient. Aqueous solubility (Sw) is the equilibrium distribution of a solute between water and solute phases. In other words, it is the maximum solute concentration possible at equilibrium, and it can function as a limiting factor in concentration dependent (for example, kinetic) processes. The octanol-water partition coefficient is the ratio of the concentration of a chemical in octanol and in water at equilibrium. Octanol is an organic solvent that is used as a surrogate for natural organic matter. This parameter is used in many environmental studies to help determine the fate of chemicals in the environment, such as predicting the extent to which a contaminant will bioaccumulate in fish. The octanol-water partition coefficient has been correlated to water solubility; therefore, the water solubility of a substance can be used to estimate its octanol-water partition coefficient. The presence of nanoparticles can influence the octanol-water partitioning of hydrophobic organic water contaminants.

Measurement techniques

We selected low molecular weight poly-aromatic hydrocabons (PAHs) for this study including anthracene, naphthalene and phenanthrene as probe molecules to study the fate and transport of hydrophobic organic pollutants in water streams nanoparticles. The experimental procedure for this study involved the addition of 0-20 mg/L of PAHs in 200 mL of octanol to 900 mL of DI water containing different concentrations of nanoparticles (ranging from 0-20 mg/L) in an Erlenmeyer flask. After stirring the flasks for 5 days the mixture was allowed to settle for 3 hours and then the aqueous and octanol layers were separated. The aqueous suspensions were divided into three portions. One portion was extracted with equal volumes of methylene chloride (MC) and hexane. The mixture was centrifuged and the supernatant organic phase was collected and injected into the Clarus 600 GC from PerkinElmer. The concentrations of PAHs in MC and hexane and water were measured by gas chromatography analysis. The second portion was centrifuged at 10,000 rpm for 30 min. The mixture was decanted and the settled nanoparticles were put in a crucible to dry in an oven at 105 ˚C for 8 hr. The mass fraction of the adsorbed organics on dried particles was analyzed using a thermal gravimetric analyzer (PerkinElmer) and FT-IR or TOC.

Pollutants sorbed on engineered nanoparticles

The sorption of pollutants onto nanoparticles in water phase will be the result of three phase partitioning of pollutants between organic phase, water and suspended solids.

Octanol-Water Partition Coefficient (Kow) This coefficient represents the ratio of the solubility of a compound in octanol (a non-polar solvent) to its solubility in water (a polar solvent). The higher to Kow, the more non-polar the compound. Kd is the ratio of pollutant attached onto the particle and in the water phase.

Where Co, Cw and Cp are concentration of the pollutant organic compounds in the non-polar organic phase, in an equal weight of water, and concentration pollutants attached on per mass of particles. Ideally, these ratios are equilibrium partitioning of pollutants between organic phase, dissolved in water phase and particulate phases.

Figure 1. Suspended solid-organic carbon partitioning coefficient versus Kow for polycyclic aromatic hydrocarbons and their derivatives (Karickhoff et. al., Water Res., 241 (1979).

Figure 2. The influence of suspended nanoparticles on octanol-water partitioning of hydrophobic organic pollutants.

Kow = Kd = Co Cp

Cw' Cw'

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Figure 3. Schematic of PerkinElmer TGA-GC-MS set up with a heated transfer capillary line.

Figure 6. TGA of phenatherene adsorption on nano-TiTO2 at pH of 10 (curve A) and 6.6 (curve B).

Figure 4. Photograph of PerkinElmer TGA-GC-MS System. Figure 7. TGA-GC-MS data with SEM image.

Figure 5. Thermal Analysis of nano-TiTO2, a) conOrganic pollutants adsorbed on nanoparticles: O-W Partitioning.

Figure 8. Absence of light made the nanoparticles less hydrophilic and increased the distribution to the organic phase.

Emitted gas collector

Sample holding pan

Heated tube to GC/MS

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Summary

• TGA-GC-MS is a useful technique to study nanoparticle influence on adsorption and partitioning PAHs.

• Presence of nano-TiO2 increased the partitioning of PAHs to water phase.

• Nanoparticles resulted in increased partitioning of PAHs; six to ten times more than in water-octanol equilibrium conditions.

• Naphthalene and phenanthrene have low water solubility but differing partitioning.

• Partitioning influence increased at higher pH.

• Absence of light made the nanoparticles less hydrophilic and increased the distribution to the organic phase.

• Study suggested that the environmental risk of NP should include their transformation and influence in the transport of other pollutants.

Additional Reading

1. PerkinElmer, Inc. Nanotechnology and Engineered Nanomaterials – A Primer, www.perkinelmer.com/nano

2. PerkinElmer, Inc. Nanomaterials Reference Library www.perkinelmer.com/nano

References

1. Bom, D., Andrews, R., Jacques, D., Anthony, J., Chen, B., Meier, M.S., Selegue, J.P., Thermogravimetric Analysis of the Oxidation of Multiwalled Carbon Nanotubes: Evidence for the Role of Defects Sites in Carbon Nanotube Chemistry, NanoLetters, 2002, 2, 6, 615-619.

2. Pinault, M., Mayne-L’Hermite, M., Reynaud, C., Beynaud, C., Beyssac, O., Rouzaud, J.N., Clinard, C., Carbon nanotube produced by aerosol pyrolysis: growth mechanisms and post-annealing effects, (2004) 13, 1266-1269.

3. Penn, S.G., He, L. and Natan, M.J., Nanoparticles for bioanalysis. Current Opinion in Chemical Biology 2003, 7, 609-615.




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