Latent Oxidative Polymerization of Catecholamines as Potential Cross-linkers for Biocompatible and Multifunctional Biopolymer Scaffolds

Electrospinning of naturally occurring biopolymers for biological applications requires postspinning cross-linking for endurance in protease-rich microenvironments and prevention of rapid dissolution. The most commonly used cross-linkers often generate cytotoxic byproducts, which necessitate high concentrations or time-consuming procedures. Herein, we report the addition of "safe" catecholamine cross-linkers to collagen or gelatin dope solutions followed by electrospinning yielded junction-containing nanofibrous mats. Subsequent in situ oxidative polymerization of the catecholamines increased the density of soldered junctions and maintained the porous nanofiber architecture. This protocol imparted photoluminescence to the biopolymers, a smooth noncytotoxic coating, and good mechanical/structural stability in aqueous solutions. The utility of our approach was demonstrated by the preparation of durable antimicrobial wound dressings and mineralized osteoconductive scaffolds via peptide antibiotics and calcium chloride (CaCl₂) incorporation into the dope solutions. The mineralized composite mats consist of amorphous calcium carbonate that enhanced the osteoblasts cell proliferation, differentiation, and expression of important osteogenic marker proteins. In proof-of-concept experiments, antibiotic-loaded mats displayed superior antimicrobial properties relative to silver (Ag)-based dressings, and accelerated wound healing in a porcine deep dermal burn injury model.