Highly efficient "grafting from" an α-helical polypeptide backbone by atom transfer radical polymerization.

Because of their favorable biodegradability, biocompatibility, regular secondary structures, and stimuli-responsiveness, synthetic polypeptides have attracted more and more attention in the biomedical material field. In this work, a novel thermo-responsive graft polypeptide, poly(L-glutamate)-graft-poly(2-(2-methoxyethoxy)ethyl methacrylate) (PLG-g-PMEO₂ MA), is prepared through a combination of ring-opening polymerization and atom transfer radical polymerization. The structure of PLG-g-PMEO₂ MA is confirmed by FT-IR, ¹H NMR, and GPC analyses. The phase transition temperature of PLG-g-PMEO₂ MA is adjustable by varying the NaCl concentration in aqueous solution. PLG-g-PMEO₂ MA adopts α-helical conformations both in aqueous solution at 25 and 60 °C and even in the solid state. In addition, PLG-g-PMEO₂ MA forms stimuli-responsive micelles with an α-helical core and a thermo-responsive shell in water.