Synthesis And Characterization Of Electroactive Poly(L-glutamic Acid) Hydrogel

As a biomedical polymer material, polyamino acid has much excellent features, such as good biodegradability, biocompatibility, promotion of tissue repair and cell growth and degradation products nontoxic, etc. So, polyamino acid has a great use in the medical field, such as controlled drug delivery and surgical suture.The biomedical field studies have shown that electric stimuli can regulate cell growth, proliferation and differentiation, enhance the endochondral ossification, and improve the repair of bone and peripheral nerve. Polyaniline, as a conductive polymer, which can respond to the electrical stimulation. However, due to poor biocompatibility and biodegradability, which limits its further application in respect of medical materials. Nowadays, people can prepare the electroactive and biodegradable materials combined by polyaniline and biodegradable materials, which have advantages of conductivity, degradability and biocompatibility, and show a good application prospects.This paper summarized the basic knowledge of drug delivery systems and drug release carriers, and mainly introduced the biodegradable polymer material poly(L-glutamic acid) and the electroactive conductive polymer aniline pentamer. Many different synthetic route of poly(L-glutamic acid) and aniline pentamer reported in the literature were also described in detail.Based on the analysis of the reported synthetic routes in the literatures, a simple and feasible synthetic route was studied out. With N-phenyl-1,4-phenylenediamine and succinic anhydride as starting materials, phenyl/carboxyl-capped aniline dimer was achieved, then reacted with p-Phenylenediamine to obtain carboxyl/carboxyl-capped aniline pentamer, again hydrolyzed to obtain amino/amino-capped aniline pentamer (AP).With y-benzyl-L-glutamate (BLG), phenylcarbinol and triphosgene as starting materials, one key intermediate was achieved, it is y-benzyl-N-carboxyl-L-glutamate (BLG-NCA). Poly(y-benzyl-N-carboxyl-L-glutamate)(PBLG) was obtained by the ring-opening polymerization with triethylamine as initiator, then deprotected under33%HBr solution in acetic acid, biodegradable poly(L-glutamic acid)(PLGA) was achieved. EDC/NHS was used to activate the carboxyl of PLGA, a biodegradable electroactive hydrogel was synthesized by the cross-linking reaction of NHS-activated PLGA with aniline pentamer (AP), and the structure of the hydrogel was characterized by FI-IR,’H-NMR, UV-vis and TGA.