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Polypeptides and polypeptoids were widely used as biomedical materials because of their good biocompatibility.In this work we reported a series of p H-responsive copolypeptides and polypeptide-polypeptoid block copolymers,i.e.random copolymers of L-glutamic acid(Glu) with L-leucine(Leu) [poly(Glu-r-Leu)s],as well as their block copolymers with polysarcosine(poly Sar).Well-defined poly(Glu-r-Leu)s with predictable compositions and molecular weights were synthesized by ring opening polymerization of corresponding N-carboxyanhydride monomers.We investigated the relationship between hydrophilicity-hydrophobicity transition and copolymer composition.With increasing Leu fraction,both the p H value of cloud point and the micellar size increased.Poly(Glu-r-Leu) with 60% Leu exhibited a cloud point at the p H of 5.0 to 6.0 the same as that in endosome and lysosome.Poly(Glu-r-Leu)-b-poly Sars assembled in phosphate buffer and performed p H-responsive morphology change from orbicular micelles at high p H to worm-like micelles at low p H.They were potential p H-responsive carriers for drug and gene delivery to enhance cargo release in cellules.
Polypeptides and polypeptoids were widely used as biomedical materials because of their good biocompatibility. In this work we reported a series of p H-responsive copolypeptides and polypeptide-polypeptoid block copolymers, ierandom copolymers of L-glutamic acid (Glu) with L-leucine (Leu) [poly (Glu-r-Leu) s], as well as their block copolymers with polysarcosine (poly Sar). Well- defined poly (Glu- r- Leu) s with predictable compositions and molecular weights were synthesized by ring opening polymerization of corresponding N-carboxyanhydride monomers. We investigated the relationship between hydrophilicity-hydrophobicity transition and copolymer composition. With increasing Leu fraction, both the p H value of cloud point and the micellar size increased. Poly (Glu-r-Leu) with 60% Leu extracted a cloud point at the pH of 5.0 to 6.0 the same as that in endosome and lysosome. Poly (Glu-r-Leu) -b-poly Sars assembled in phosphate buffer and performed pH-responsive morphology change from orbicular micelles at high p H to worm-like micelles at low p H. They were potential p H-responsive carriers for drug and gene delivery to enhance cargo release in cellules.