Electrospun Polymers in Cornea Repair and Regeneration

Abstract

Purpose: : Electrospun polymers are an excellent example of multi-functional biomaterials, affording a micro- or nanofibrous mechanical support for cell and tissue growth, a high surface area and controllable surface chemistry, tailored porosity to promote vascularization and innervation, and a matrix for the delivery of bioactive molecules. Potential uses in corneal repair include fabrication of synthetic corneas from collagen nanofibers and drug-releasing scaffolds to facilitate the healing of damaged corneas. Attention is given here to the latter, where electrospun hydrophilic and hydrophobic polymer fibers serve as matrices for containment and release of therapeutic molecules. In cases where the polymer and drug are soluble in a common solvent, drug containment is easily achieved, but incorporating water-soluble small molecules into otherwise hydrophobic polymers presents a challenge. One viable approach involves the use of ‘two-phase’ or ‘biphasic’ electrospinning in which dispersions of water droplets in a polymer/organic solvent are electrospun.

Methods: : Poly(ethylene-co-vinyl acetate) and PLGA in chloroform and PVA in water were electrospun with all solutions containing variable amounts of antibiotic. Entrapment of water-soluble macromolecules was accomplished using our biphasic electrospinning approach. Electrospun mats were characterized via scanning electron microscopy to determine fiber diameters, by dynamic mechanical analysis to evaluate thermal and mechanical properties of the scaffolds, and by uv-vis spectroscopy to monitor drug release.

Results: : Electrospun mats of varying thickness and fiber diameters containing antibiotics were successfully produced from a multitude of polymer systems. Additionally, layered mats derived from two different polymers were also developed for the ability to demonstrate dual-component release. Release profiles typically show an initial ‘burst’ release but longer-term release can be relatively steady depending upon the specific polymer/drug system.

Conclusions: : Electrospinning is a convenient and simple method to prepare fibrous polymer constructs containing therapeutic molecules that can be released over several days. We foresee interesting applications of such materials in cornea repair and, longer term, in cornea regeneration.

Keywords: contact lens • wound healing • cornea: basic science