1

Nanomaterials must have unique and novel physicaland/or chemical characteristics which can aid in the designof bio-sensors with improved analytical characteristics:

Nanomaterials in Bio-Sensors

High surface ratio

Novel electro-optical properties

Increased catalytic activity

Enhanced electron transfer

ICAS 2006. N. A. Chaniotakis University of Crete

Immobilization and Stabilization matrices, Mediators, Transduction platforms

Carbon Materials for Immobilization and stabilization

Carbon Nanomaterials in Bio-Sensors

Fullerenes CarbonNanotubes

ICAS 2006. N. A. Chaniotakis University of Crete

Nanotubes

NanoporousCarbon

CarbonNanofibers

Stabilization in Confined SpacesEffect of confinement on the folding free energy as a function of the cage size

The radius of the protein in the native state (aN) was given by 3.73N1/3

Cage size (in units of 2aN) is given on a log scale.

Ν = 100Ν = 200

H.X. Zhou, K.A. Dill Biochemistry, 2001, 40 (38), 11289

Active Surface

Stabilization: Protein and Cage SizeMaximum stabilization of proteins in spherical cages with diameter of 2 to 6 times the diameter of the native protein

~20 -100 nm

~7 nm Glucose

Gluconic Acid

Enzyme

Enzyme withpolyelectrolyte

ICAS 2006. N. A. Chaniotakis University of Crete

2

50

60

70 dichlorvos paraoxon

Calibration Curve

Mutant (E69Y, Y71D) Drosophila melanogaster AChE+350 mV 25 oC

Porous Carbon Pesticide Biosensor

Continuous Operation

100

120

140

Act

ivity

free m-AChEm-AChE in carbon nanopores

8 10 12 14 16 18 20

0

10

20

30

40

50

% In

hibi

tion

-log[pesticide], M

S. Sotiropoulou, N.A. Chaniotakis, Biosens.Bioelectron. 2005, 20, 2347S. Sotiropoulou, N.A. Chaniotakis, Anal.Chim. Acta 2005, 530, 199

0 20 40 60 800

20

40

60

80

100

% R

emai

ning

A

time (hr)

Carbon Nanotubes

Pt Transducer

Glucose

Gluconic acid

e-

EnzymeGlucose Oxidase

The carbon nanotubes were grown by the CVD method on a platinum substrate, thusproviding an array of MWNT, 15-20 microns long and with an internal diameter of150nm.

S. Sotiropoulou, N.A. Chaniotakis, Anal. Bioanal. Chem. 2003, 375, 103

Carbon Nanotubes

S. Sotiropoulou, N.A. Chaniotakis, Anal. Bioanal. Chem. 2003, 375, 103

1.0

1.5

2.0

(µΑ

)

Carbon Nanotube Biosensor

Linear range: 0.05 - 2.5 MSensitivity: 93.9 ± 0.4 µA mM-1 cm-2

0.0 0.5 1.0 1.5 2.0 2.5

0.0

0.5

∆Ι

[glucose] (mM)

S. Sotiropoulou, N.A. Chaniotakis, Anal. Bioanal. Chem. 2003, 375, 103

3

Carbon Nanofiber Biosensor

Carbon NanotubesCarbon NanofibersV. Vamvakaki, K. Tsagaraki, N.A. Chaniotakis, Anal. Chem. Is press

Carbon Nanofiber BiosensorTable 1. Carbon nanofiber physical characteristics

Nanofiber Grade LHT HTE GFE

Diameter (nm) 70-150 80-150 80-150

N2 Surface Area (m2/g) 43 80-100 > 50

Density (g/cm3) > 1.95 1.98 2.17

Heat treatment (o C) 1000 1000 3000

Metal Content (wt. %) < 0.50 < 0.50 < 0.01

Electrical Resistivity (Ohm/cm) < 10-3 < 10-3 < 10-3

SEM image of HTE Nanofibersmean diameter ~ 110 nmlength ~ tenths of nanometers

V. Vamvakaki, K. Tsagaraki, N.A. Chaniotakis, Anal. Chem. Is press

120

130

140

150

ing

Act

ivity

Carbon Nanofiber BioSensor

Stability Study

0 20 40 60 80 100

70

80

90

100

110

% R

emai

ni

t (hours)

GFE HTE LHT NANOTUBES GRAP HITE

Reproducibility: RSD value < 1% (N = 3)V. Vamvakaki, K. Tsagaraki, N.A. Chaniotakis, Anal. Chem. Is press

Carbon Structures as Mediators

4

Carbon Structures as Mediators

S. Licht et al./ Solar Energy Materials and Solar Cells 51 (1998) 9-19

Fullerenes

Fullerene C60multiple redox stateslow solubility in aqueous solutionsstable in many redox forms

Enzyme Glucose oxidase

Glucose

Gluconic acid

FAD

FADHMediator(ox)

Mediator(red)

+350 mV

e-

ICAS 2006. N. A. Chaniotakis University of Crete

Fullerenes

V. Gavalas, N.A. Chaniotakis, Anal. Chim. Acta 2000, 409, 131

Calibration curve of the glucose biosensorcontaining 1.7µg C60/mg of electrodematerial. Measurements were performedin 10mM phosphate buffer, pH=7.5 underargon, at +350mV vs. Ag/AgCl.

Hydrodynamic voltammogram for theglucose biosensors constructed usingcarbon incubated for: 0 ( ), 4 ( ), 5 ( )cycles in the toluene-C60 solution

Fullerenes

Fullerene MediatorEnzyme

Glucose Oxidase

GlucoseFAD

+350mV+100mV

Flowchart of the processes involved in a light induced fullerene mediated electrochemical biosensor. The operating potential has dropped to +100 mV.

Gluconic acid

e-FADH

ICAS 2006. N. A. Chaniotakis University of Crete

5

Fullerenes

0.0

-0.2

-0.4

Light ONΑ)

-1 0 1 2 3 4 50.8

0.6

0.4

0.2Light ON

Light OFF∆Ι (

µΑ

[Glucose], mMICAS 2006. N. A. Chaniotakis University of Crete

Carbon Structures as Mediators

S. Licht et al./ Solar Energy Materials and Solar Cells 51 (1998) 9-19

Conclusions-Future Directions

Carbon nanomaterials have unique properties that are ideal for the development of

highly stable,reproduciblereproducible,and sensitive

chemical sensors andbiosensors