Peptide-Based Polyelectrolyte Promotes Directional and Long Neurite Outgrowth.

Neural tissue engineering has emerged as a promising technology to cure neural damages. Although various synthetic polymers with good biocompatibility and biodegradability have been adopted as candidate materials for scaffolds, most of them require the incorporation of biomolecules or conductive materials to promote the growth of long axons. Herein we demonstrate for the first time a unique peptide-based polyelectrolyte that is ionically conductive and contains a neurotransmitter, glutamic acid. The designed polymer, sodium salt of poly(γ-benzyl-l-glutamate)--poly(l-glutamic acid) (PBGA20-Na), was synthesized and fabricated into a 3D fibrous scaffold with aligned fibers. Neuron-like rat pheochromocytoma (PC12) cells were cultured on the scaffolds to evaluate cell proliferation and differentiation with or without electrical stimulation. The results show that with both electrical and biochemical cues presented in the polyelectrolyte, PBGA20-Na promotes longer neurite outgrowth compared with the neutral poly(γ-benzyl-l-glutamate) (PBG) and the poly(γ-benzyl-l-glutamate)--poly(l-glutamic acid) (PBGA20). Furthermore, the neurite length of the cells cultured on PBGA20-Na is more than twice as long compared with the conventional biopolymer, polycaprolactone. In conclusion, PBGA20-Na is a promising biomaterial for neural tissue engineering and drug-screening platforms.