Bicomponent Fibrous Scaffolds of Controlled Composition for Tissue Engineering Applications

Abstract

Electrospinning has been widely studied for constructing tissue engineering scaffolds because of the morphological and size effects of electrospun fibers on cell behavior. Research on electrospun tissue engineering scaffolds has been based mainly on using solutions of single polymer or blends of polymers dissolved in common solvents, which has put limitations to scaffolds that can be built. There is an increasing need for using the multi-source and multi-power electrospinning approach to fabricate multicomponent fibrous scaffolds because these scaffolds have great potential for tissue engineering and controlled (drug) release applications. In the present study, bicomponent fibrous scaffolds were fabricated through dual-source and dual-power electrospinning using poly(L-lactic acid) (PLLA) and gelatin polymers. The experimental setup ensured that the solution and electrospinning parameters for each electrospun fibrous component were controlled separately and hence the morphology of electrospun fibers could be controlled and optimized. By adjusting the number of syringes that fed polymer solutions, the composition of bicomponent scaffolds (i.e. the weight percentage of gelatin varying from 0 to 100%) could also be controlled. Such controls would yield scaffolds of desired properties (hydrophilicity, degradation rate, strength, etc.) After electrospinning, pure gelatin scaffolds and bicomponent scaffolds were crosslinked by glutaraldehyde (GA) and genipin, respectively, using different crosslinking methods. Both crosslinked and non-crosslinked scaffolds were studied using various techniques (scanning electron microscopy (SEM) for scaffold morphology, differential scanning calorimetry (DSC) for polymer crystallinity, contact angle measurement for hydrophilicity, tensile testing for mechanical properties and crosslinking efficiency, etc.). It was found that the bicomponent scaffolds were more hydrophilic than pure PLLA scaffolds due to the presence of gelatin fibers. The tensile strength of bicomponent scaffolds was also increased after crosslinking. Using our experimental setup, bicomponent scaffolds could be constructed for tissue engineering with enhanced mechanical properties, biocompatibility and biodegradability. Furthermore, in the bicomponent scaffolds, while PLLA fibers could act as the structural component with a slower degradation rate, the gelatin fibers could be used as a carrier for therapeutic agents (drugs and therapeutic biomolecules). With controlled degrees of the crosslinking of gelatin, the release of therapeutic agents from gelatin fibers would be controlled.