Dhan B. Khadka

Protein- and peptide-based electrospun nanofibers in medical biomaterials

UNLABELLED Electrospun fibers are being studied and developed because they hold considerable promise for realizing some advantages of nanostructured materials. The fibers can be made of biocompatible and biodegradable polymers. Electrospinning has therefore attracted interest in biotechnology and medicine, and there has been rapid growth in this area in recent years. This review presents an introduction to polymer nanofiber electrospinning, focusing on the use of natural proteins and synthetic peptides. We summarize key physical properties of protein-based and peptide-based nanofiber mats, survey biomedical applications of these materials, identify key challenges, and outline future prospects for development of the technology for tissue engineering, drug delivery, wound healing, and biosensors. FROM THE CLINICAL EDITOR This review focuses on polymer nanofiber electrospinning using natural proteins and synthetic peptides. The authors describe key properties and applications of these materials, and outline future prospects for tissue engineering, drug delivery, wound healing, and biosensors based on these nanomats and nanofibers.

A synthetic polypeptide electrospun biomaterial.

Fiber mats of a synthetic anionic copolypeptide of l-glutamic acid and l-tyrosine (PLEY) have been produced by electrospinning, and physical, chemical, and biological properties of the fibers have been characterized in vitro. Fibers were obtained from polymer dissolved in water at concentrations of 20-60% (w/v) but not below this range. Applied voltage and spinneret-collector distance were also found to influence polymer spinnability. Oriented fibers were obtained by changing the geometry of the collector. Fiber diameter was measured by scanning electron microscopy (SEM). A common chemical reagent was used to cross-link polymers postspinning. Fiber solubility in aqueous solution varied as a function of cross-linking time. Cationic polypeptides labeled with a fluorescent dye became noncovalently associated with cross-linked fibers, enabling visualization by fluorescence microscopy. Spectroscopy provided information on polymer chain conformation in solution and in fibers. Degradation of cross-linked fibers by different proteases has been demonstrated. Fibroblasts were cultured on cross-linked fiber mats to test basic cytocompatibility. Synthetic polypeptide fiber mats may be useful in applications in medicine, biotechnology, and other areas.

Insoluble Synthetic Polypeptide Mats from Aqueous Solution by Electrospinning

Water-insoluble nanofiber mats of synthetic polypeptides of defined composition have been prepared by a process involving electrospinning from aqueous solution. L-ornithine is a physiological amino acid. Fibers of poly(L-ornithine) (PLO) were produced at feedstock concentrations above 20% w/v. Applied voltage and needle-to-collector distance were crucial for nanofiber formation. Attractive fibers were obtained at 35-40% w/v. Fiber diameter and mat morphology have been characterized by electron microscopy. Polymer cross-linking with glutaraldehyde (GTA) vapor rendered fiber mats water-insoluble. The study has yielded two advances on previous work in the area: avoidance of an animal source of peptides and avoidance of inorganic solvent.