title: Synthesis of temperature and pH-responsive crosslinked micelles from polypeptide-based graft copolymer.
abstract: A polypeptide-based double hydrophilic graft copolymer was synthesized by the sequential grafting of poly(N-isopropylacrylamide) (PNIPAM) and 2-hydroxyethyl methacrylate (HEMA) onto poly(l-glutamic acid) (PGA) backbone. The copolymers were sensitive to both temperature and pH. The phase transition and aggregation behaviors of the graft copolymers in aqueous solutions were investigated by the turbidity measurements and dynamic laser scattering (DLS). The light transmittance decrease of the copolymers at temperature above lower critical solution temperature (LCST) was remarkably weakened at pH around 6.5 due to the coil to α helix change of PGA chain induced by pH. The copolymers can self-assembly into micelles with PNIPAM cores in the aqueous solution at pH 8.0 and 60°C. Subsequently, polymerization of HEMA led to the facile preparation of crosslinked micelles, which were observed directly by transmission electron microscopy (TEM). The temperature controlled shrinkage behaviors of crosslinked micelles highly depended on the pH values of the solution. The crosslinked micelles aggregated at pH 5.0 due to the increased hydrophobic interactions among them induced by the protonation of PGA component. These crosslinked micelles have promising applications as intelligent drug delivery vehicles.
authors.affiliation: Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, PR China.
authors.forename: Changwen
authors.initials: C
authors.lastname: Zhao
authors.forename: Pan
authors.initials: P
authors.lastname: He
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Xiao
authors.forename: Xiaoye
authors.initials: X
authors.lastname: Gao
authors.forename: Xiuli
authors.initials: X
authors.lastname: Zhuang
authors.forename: Xuesi
authors.initials: X
authors.lastname: Chen
mesh_terms: D000178:Acrylamides / Q000138:chemical synthesis / Q000737:chemistry*; D000180:Acrylic Resins; D006863:Hydrogen-Ion Concentration; D008689:Methacrylates / Q000138:chemical synthesis / Q000737:chemistry*; D008823:Micelles; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011099:Polyglutamic Acid / Q000138:chemical synthesis / Q000737:chemistry*; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D013696:Temperature
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D008689:Methacrylates; D008823:Micelles; D010455:Peptides; D011108:Polymers; C052970:poly-N-isopropylacrylamide; D011099:Polyglutamic Acid; C005044:hydroxyethyl methacrylate