Mild immobilization of diverse macromolecular bioactive agents onto multifunctional fibrous membranes prepared by coaxial electrospinning

Coaxial electrospinning was proved to be a facile method to produce multifunctional fibrous matrices which could essentially emulate certain features of native extracellular matrix. In order to further confer capability of immobilizing diverse macromolecular bioactive agents to the fibers, composite membranes composed of cationized gelatin-coated polycaprolactone (PCL) fibers were prepared by coaxial electrospinning. Gelatin was cationized by derivation with N,N-dimethylethylenediamine. The cationized gelatin (CG) was used as a shell material for constructing a core–shell fibrous membrane. PCL formed the core section of the core–shell fibers thereby improving the mechanical properties of nanofibrous CG hydrogel. The outer CG layer was crosslinked by exposing the membranes in glutaraldehyde vapor. The adsorption behaviors of FITC-labeled bovine serum albumin (FITC–BSA) or FITC–heparin onto the fibers were investigated. The core–shell fibers could effectively immobilize the two types of agents under mild conditions. The adsorption amount could reach about 12 μg of BSA per mg of membrane and 23 μg mg−1 for heparin. Furthermore, vascular endothelial growth factor (VEGF) could be conveniently impregnated into the fibers through specific interactions with the adsorbed heparin in the outer CG layer. Sustained release of bioactive VEGF could be achieved for more than 15 days.