Characterization of proton exchange membrane fuel cells with catalyst layers obtained by electrospraying.

Electrospraying of Pt/C-Nafion-alcohol dispersions was employed as a new method to deposit catalyst layers on Nafion membranes for hydrogen/oxygen͑air͒ fuel cells. It is shown that single cells with catalyst layers obtained by electrospraying exhibit good initial performance ͑ca. 1 A/cm 2 @ 700mV͒ at 80°C and 300 kPa without the need for hot-pressing of the electrode layer. Analysis of polarization losses reveals a significant contribution of mass-transport losses to the fuel cell performance for hydrogen/ air fuel cells. We suggest that control of electrospray processing parameters can lead to tailored electrode structures where such mass transport losses are mitigated

Electrospinning of nanofiber fibrinogen structures

The first results of electrospinning fibrinogen nanofibers for use as a tissue-engineering scaffold, wound dressing, or hemostatic bandage are reported. Structures composed of fibrinogen fibers with an average diameter of 80-700 nm were electrospun from solutions composed of human or bovine fibrinogen fraction I dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol and minimal essential medium (Earle\u27s salts). In summary, the electrospinning process is a simple and efficient technique for the fabrication of 3D structures composed of fibrinogen fibers, as would be present in the physiologic environment

Electrospinning of collagen nanofibers

Electrospinning is a fabrication process that uses an electric field to control the deposition of polymer fibers onto a target substrate. This electrostatic processing strategy can be used to fabricate fibrous polymer mats composed of fiber diameters ranging from several microns down to 100 nm or less. In this study, we describe how electrospinning can be adapted to produce tissue-engineering scaffolds composed of collagen nanofibers. Optimizing conditions for calfskin type I collagen produced a matrix composed of 100 nm fibers that exhibited the 67 nm banding pattern that is characteristic of native collagen. The structural properties of electrospun collagen varied with the tissue of origin (type I from skin vs type I from placenta), the isotype (type I vs type III), and the concentration of the collagen solution used to spin the fibers. Electrospinning is a rapid and efficient process that can be used to selectively deposit polymers in a random fashion or along a predetermined and defined axis. Toward that end, our experiments demonstrate that it is possible to tailor subtle mechanical properties into a matrix by controlling fiber orientation. The inherent properties of the electrospinning process make it possible to fabricate complex, and seamless, three-dimensional shapes. Electrospun collagen promotes cell growth and the penetration of cells into the engineered matrix. The structural, material, and biological properties of electrospun collagen suggest that this material may represent a nearly ideal tissue engineering scaffold

Electrospraying and Electrospinning of Polymers for Biomedical Applications. Poly(Lactic-Co-Glycolic Acid) and Poly(Ethylene-Co-Vinylacetate)

Significant opportunities exist for the processing of polymers (homopolymers and blends) using electric fields. Specific attention is given here to electrospinning, but we note that electroaerosol formation and field-modulated film casting represent additional processing options. Of particular interest is the ability to generate polymer fibers of sub-micron dimensions using electrospinning, down to about 0.05 microns (50 nm), a size range that has been traditionally difficult to access. In our work, poly(lactic-co-glycolic acid), PLA/PGA, poly(lactic acid) PLA, and poly(ethylene-co-vinylacetate) (PEVA) have been deposited from solutions in methylene chloride or chloroform by electrospraying or electrospinning to afford morphologically tailored materials for tissue engineering and related applications. Low solution concentrations tend to favor electrostatic spraying ('electro-aerosolization') while higher concentrations lead to spinning on fibrous mats. Preliminary observations of muscle cell growth on PLA electrospun mats are reported

Two-phase electrospinning from a single electrified jet: Microencapsulation of aqueous reservoirs in poly(ethylene-co-vinyl acetate) fibers

An overview is given of a new and potentially useful expansion of the scope of electrospinning, namely, the encapsulation of aqueous domains within thin polymer fibers. It is demonstrated that EVA fibers containing aqueous reservoirs are easily electrospun and that osmotic swelling can lead to expansion and eventually the bursting of these reservoirs