title: Thermo-/pH-dual responsive properties of hyperbranched polyethylenimine grafted by phenylalanine.
abstract: Novel thermo- and pH-dual responsive amphiphilic copolymers were synthesized based on hyperbranched polyethylenimine (PEI) by grafting L-phenylalanine. The phenylalanine-modified PEI exhibited lower cytotoxicity than commercial PEI. These copolymers showed the phenomena of phase transitions in response to pH and temperature. The dilute copolymer solution at lower pH displayed the higher LCST. Furthermore, LCST increased with the increasing of phenylalanine grafting density. LCST of these copolymers were tunable from 7.2 to 59.6 °C by the degree of amidation and pH of solution. DLS and TEM experiments certified that the copolymer chains aggregated to form small size particles as increasing the temperature above LCST. For these reasons, the obtained smart copolymers were considered to be potential gene/drug carriers in biomedical field.
authors.affiliation: Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Jialiang
authors.initials: J
authors.lastname: Xia
authors.forename: Huayu
authors.initials: H
authors.lastname: Tian
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Tang
authors.forename: Chaoliang
authors.initials: C
authors.lastname: He
authors.forename: Xuesi
authors.initials: X
authors.lastname: Chen
mesh_terms: D001672:Biocompatible Materials; D004337:Drug Carriers; D018014:Gene Transfer Techniques; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010316:Particle Size; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000633:toxicity; D011094:Polyethyleneimine / Q000138:chemical synthesis* / Q000633:toxicity; D013678:Technology, Pharmaceutical / Q000379:methods; D013696:Temperature
chemical_list: D001672:Biocompatible Materials; D004337:Drug Carriers; D010649:Phenylalanine; D011094:Polyethyleneimine