Amine functionalization of collagen matrices with multifunctional polyethylene glycol systems

A method to functionalize collagen-based biomaterials with free amine groups was established in an attempt to improve their potential for tethering or bioactive molecules. Collagen sponges were incorporated with amine-terminated multifunctional polyethylene glycol (PEG) derivatives after N-(3-dimethylaminopropyl)-N-ethylcar-bodiimide and N-hydroxysuccinimide (EDC NHS) cross-linking. The extent of the incorporation of different amounts and different numbers of active moieties of amine-terminated PEG systems into the collagen scaffolds was evaluated using ninhydrin assay, Fourier transform infrared spectrophotometry collagenase degradation assay, denaturation temperature measurements, and in vitro cell studies. A 3% 8-arm amine-terminated PEG was found to be the minimum required effective concentration to functionalize EDC NHS stabilized collagen scaffolds. EDC NHS stabilized scaffolds treated with 3% 8-arm amine-terminated PEG exhibited significantly improved denaturation temperature and resistance to collagenase degradation over non-cross-linked scaffolds (p 0.002). Biological evaluation using 3T3 cells demonstrated that the produced scaffolds facilitated maintenance of the cells morphology, metabolic activity, and ability to proliferate in vitro. Overall, our results indicate that amine-terminated PEG systems can be used as means to enhance the functionality of collagenous structures.