RAFT polymerization of a RGD peptide-based methacrylamide monomer for cell adhesion

Synthetic peptides containing the arginine-glycine-aspartate (RGD) motif have been used extensively as inhibitors of integrin-ligand interactions in studies of cell adhesion and cell target moiety. MARGD (sequences: Phe-Gly-Arg-Gly-Asp-Ser), a methacrylamide monomer containing a pending RGD peptide, was synthesized and obtained in high purity (≥90%) via an automated peptide synthesizer followed by a simple precipitation in diethyl ether. MARGD can be polymerised by reversible addition-fragmentation chain transfer (RAFT) polymerization to afford well-defined polymers containing a RGD peptide group with controlled molecular weight, low dispersity (< 1.25), and a precise chain end structure. In this study, linear pseudo-first-order kinetics and number average molecular weight dependence on conversion were observed during the RAFT polymerization. Diblock peptide-polymer conjugates were prepared using PMARGD as a macro-chain transfer agent or using MARGD as a monomer, and the resulting diblock conjugates all showed low dispersities. The cytotoxicity study using mouse fibroblast cells (L929) revealed that the bioconjugates are non-toxic up to high concentration. Furthermore, enhanced cell adhesion was observed when the bioconjugates immobilized on the glass slide surfaces. This study provides a novel and efficient strategy to access well-defined peptide-polymer conjugates with diversity for both peptides and polymers.