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-PMEO(2)MA), is prepared through a combination of ring-opening polymerization and atom transfer radical polymerization. The structure of PLG-g-PMEO(2)MA is confirmed by FT-IR, (1)H NMR, and GPC analyses. The phase transition temperature of PLG-g-PMEO(2)MA is adjustable by varying the NaCl concentration in aqueous solution. PLG-g-PMEO(2)MA adopts alpha-helical conformations both in aqueous solution at 25 and 60 degrees C and even in the solid state. In addition, PLG-g-PMEO(2)MA forms stimuli-responsive micelles with an alpha-helical core and a thermo-responsive shell in water.