Polymer chains incorporating caprolactone and arginine-glycine-aspartic acid functionalities: Synthesis, characterization and biological response in vitro of the Schwann cell

This study describes a strategy for the covalent immobilization of active adhesion peptide moieties onto polymers through the intermediacy of itaconic acid. The arginine-glycine-aspartic acid peptide was grafted to a novel poly(caprolactone 2-(methacryloyloxy) ethyl ester)-co-itaconic acid bulk biomaterial, in order to improve the cell adhesion of the polymer. First, the arginine-glycine-aspartic acid sequence was grafted onto itaconic acid via an amidation reaction using N(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide as activation complex. The itaconic acid-arginine-glycine-aspartic acid macromer was characterized by Fourier transform infrared spectroscopy and H-1-NMR, yielding a functionalization degree of 85%. In a second step, poly(caprolactone 2-(methacryloyloxy) ethyl ester-co-itaconic acid-arginine-glycine-aspartic acid) (with a feed mixture of 90 wt% of caprolactone 2-(methacryloyloxy) ethyl ester and 10 wt% of itaconic acid-arginine-glycine-aspartic acid macromer) and a series of copolymers of caprolactone 2-(methacryloyloxy) ethyl ester and itaconic acid with different compositions (weight fractions of itaconic acid up to 20 wt%) were synthesized by radical copolymerization. The microstructure and network architecture of the new polymer systems were investigated. Mechanical moduli of poly(caprolactone 2-(methacryloyloxy) ethyl ester-co-itaconic acid), evaluated by dynamic-mechanical analysis, increase with the itaconic acid content. In poly(caprolactone 2-(methacryloyloxy) ethyl ester-co-itaconic acid-arginine-glycine-aspartic acid), the glass transition temperature and the mechanical moduli of the system are smaller than in the nonfunctionalized poly(caprolactone 2-(methacryloyloxy) ethyl ester-co-itaconic acid) copolymers, and the polymer is less hydrophilic. The results indicate that arginine-glycine-aspartic acid grafting of poly(caprolactone 2-(methacryloyloxy) ethyl ester-co-itaconic acid) copolymer networks can be useful for tissue engineering applications, because regenerative processes in the nervous system can be promoted and accelerated, thus, opening a possibility to generate materials with a high potential for clinical applicability.