ε-Methacryloyl-L-lysine based polypeptides and their thiol-ene click functionalization

Facile synthesis of biopolymers that facilitate versatile post-polymerization modification is of great interest for biotechnological and biomedical applications. In this study, a methacryloyl-substituted L-lysine N-carboxyanhydride (LysMA-NCA) monomer was designed and synthesized, and methacryloyl-functionalized polypeptides were prepared through the ring opening polymerization (ROP) of the L-lysine-based monomer. The post-polymerization functionalization of the methacryloyl-containing polypeptides with various thiol-containing molecules was achieved with high efficiency through facile radical-mediated thiol-ene chemistry. Moreover, a block copolypeptide bearing both methacryloyl and alkynyl pendants was developed through successive ROP of LysMA-NCA and gamma-propargyl-L-glutamate (PPLG-NCA). The sequential modification of the block copolypeptide with hydrophilic and hydrophobic molecules, respectively, was achieved by the successive alkyne-azido and thiol-ene "click" reactions. Overall, the facile synthesis of polypeptides bearing functional substituents and their versatile post-polymerization modification may serve as a useful platform for the development of various functional polymers.