Chirality and helicity of poly-benzyl-L-glutamate in liquid crystals and a wave structure that mimics collagen helicity in crimp

Ideal biocompatible polymers must show a mimetic superstructure with biological supra-organization. Collagen-rich structures like tendons and ligaments are materials with various levels of order, from molecules to bundles of fibers, which affect their biomechanical properties and cellular interactions. Poly-benzyl-L-glutamate (PBLG) displaying helicity was used here to test the development of wave-like structures as those occurring in collagen fibers. Birefringence of PBLG under various crystallization conditions was studied with a lambda/4 compensator according to Sénarmont. Qualitative observations were plainly sufficient to conclude that the PBLG fibrils were supra-organized helically as a chiral object. During crystallization stretched PBLG formed a helical superstructure with characteristic striation resembling waves (crimp). Supported by optical anisotropy findings, a twisted grain boundary liquid crystal type is proposed as a transition phase in the formation of the PBLG chiral object. A similarity with the wavy organization (crimp) of collagen bundles is proposed.