Novel electrospun funtionalized nanofibers based on biopolymers

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Transcript of Novel electrospun funtionalized nanofibers based on biopolymers

  • 1. Sergio Torres-Giner1, Avelina Fernandez1, Enrique Gimenez2, Mara Jos Ocio1,3 and Jos Mara Lagarn1 1 Novel Materials and Nanotechnology, IATA-CSIC, Apartado Correos 73, 46100 Burjassot, Spain2 Area of Materials, ESID, University Jaume I, 12071, Castellon, Spain 3 Dpto. Medicina Preventiva, Faculty of Phamarcy, University of Valencia, 46100 Burjassot, Spain e-mail: [email protected] ELECTROSPINNING OUTLINE BASIC SETUPElectrospinning is a novel and effective method of producing nanofibers by the Variable high voltage 0-30 kVapplication of a strong electrostatic fieldpower supplyIt results in an ultrathin fiber mat formation from a wide range of polymers,Stainless-steel needle withincluding biopolymerspolymer solutionOptimization of the process parameters can lead to white colored networks, Digitally controlled syringe pumpwith fiber diameters ranging from less than a 100 nm to above 1 micron connected toneedle throughNanofibers generally tend to exhibit tubular-like shapes, but more complex fiber PTFE wiremorphologies such as nanobeads, branched fibers or flat ribbons can be alsoGrounded copper plate asobservedScheme of electrospinning apparatus Our experimental laboratorycollectorelectrospinning device RESULTSThe electrospinning technology, which has mainly dealt with conventional organic polymers that could be synthesized with sufficiently high molecular weights and could be dissolved in appropriate solvents, opens up enormous possibilities forthe implementation of bio-based materials and food hydrocolloids in numerous applications. Here we summarize the development and properties of novel biodegradable and renewable structures based on electrospun nanofibers from differentbiopolymers. Due to the easy spinnability of proteins as zein or collagen and polysaccharides as chitosan based on alcohol or acid solutions, their nanostructure network mats can be controlled in a several ways to provide them with desiredfunctional requirements. Thus, tubular nanofibers, flat nanofibers or even nanobeads, with a wide range of diameters, can be developed modifying the process parameters. Post-treatments of the mats with specific solvents can greatly increasethe surface area of the nanofibers when switching their structure from a solid to a porous one. Electrospinning is also an optimum tool to produce new multipurpose materials by polymer blending, which usually turns out in a beaded nanofiberformation. The technique can also support the introduction of compounds from different nature inside the nanofibers. For instance, several efforts are being focused on the introduction of smectine nanoclays inside nanofibers as reinforcingmaterials. Others are encouraged to functionalize fibers with biological substances, such as antioxidants or enzymes. For some specific applications, it is often also necessary to confer mechanical firmness and specific resistance. Byintroduction of exogeneous crosslinking into the molecular structure with some functional natural substances, such as enzymes, it can bridge and link nanofibers to construct an interpenetrating network. The morphology of the nanofiber mats iseasily characterized by scanning electron microscopy (SEM), polarized optical microscopy and Raman imaging techniques. Clay reinforced fibers can be well-resolved by transmission electron microscopy (TEM). Additional characterization ofthe glass transition temperature (Tg) and of the improved thermal stability of the networks is carried out by Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA), respectively. These techniques indicate that the Tgand the thermal stability are increased in the electrospun mats compared to solution cast films1. These changes are likely related to the observed solvent removal efficiency and different molecular structure determined by FTIR spectroscopy inthe nanofibers. In fact, this clearly indicates that the protein prolamine secondary structure can be found to be strongly dependent on the specific processing conditions under which the material is obtained1,2 1000 nm Electrospun morphologies Blend beaded nanofibersMineral nanoparticles Nanofibers crosslinked byaccording to process Nanofibers presenting hollow with antimicrobialincorporated directly tomeans of an enzymaticparameters interiorsproperties biopolymer nanofibers reaction ADVANTAGES & APPLICATIONS Electrospun nanofibers exhibit an array of unique features and properties that distinguish them from other structures using conventional mechanical extrusion or spinning process: reasonably much thin diameter, high surface-to-volume ratio, porous high density structure and easily all fully inter-connected 3D network Electrospinning also offers the advantage to help handling biopolymers because materials can turn extremely easy and stable, becoming white, free-solvent based structures with improved thermal properties These novel biodegradable and renewable structures can be interesting in various applications. For instance, nanofibers from proteins such as zein, polysaccharides such as chitosan or their blends zein/chitosan can bring novel functionalities over the food or pharmaceutical industry. Collagen crosslinked nanofiber mats can enhance integration of tissue-engineered constructs and improve the performance of biotechnological cell culture supports in the biomedical field In addition, electrospinning can probably be integrated with conventional lithographic techniques to form a new fabrication platform for generating patterned microstructures from various materials and on a broad range of length scales for use in many application fields including intelligent, active and bioacive packaging. Introducing diverse components inside these nanostructures can also possibility future new uses for biopolymers in a wide range of industrial sectors, including: a) Biological compounds which are encapsulated inside nanofibers should be useful to provide improved delivery methods for small molecules, such as peptides, proteins and nucleic acids. Therapeutic compounds can be then conveniently incorporated into the carrier biopolymers using electrospinning: the drug release profile can be finely tailored by a modulation on the morphology, porosity, and composition of the nanofiber network. The very small diameter of the nanofibers can provide short diffusion passage length and high surface area which are helpful to a mass transfer and efficient drug release b) Nanofibers containing mineral particles should result very attractive because of their unique performance in mechanical, thermal, electrical, and barrier properties. Through electrospinning, it would be possible to combine the flexibility of some biopolymers with the high strength and high modulus of certain inorganic components to produce a new array of biohybrid materials ACKNOWLEDGEMENTS The authors would like to thank the MEC (Project MAT2006-10261-C03), Nanobiomatters Ltd. (Paterna, Spain) and the IP of the EU, NEWBONE for financial support REFERENCES 1.Torres-Giner, S.; Gimenez, E.; Lagaron, J.M. Characterization of the morphology and thermal properties of Zein Prolamine nanostructures obtained by electrospinning. Food Hydrocolloids 2008, 22, 601-614. 2.2. Lagaron, J.M.; Gimenez, E; Sanchez-Garcia; M.A.; Ocio; M.J.; Fendler, A. Second Generation Nanocomposites: A Must in Passive and Active Packaging and Biopackaging Applications. The 15th IAPRI WorldConference in Packaging 2006, Tokio, Japan