title: Synthesis of agarose-graft-poly[3-dimethyl (methacryloyloxyethyl) ammonium propanesulfonate] zwitterionic graft copolymers via ATRP and their thermally-induced aggregation behavior in aqueous media.
abstract: A novel polysaccharide-based zwitterionic copolymer, agarose-graft-poly[3-dimethyl (methacryloyloxyethyl) ammonium propanesulfonate] (agarose-g-PDMAPS) with UCST, depending both on hydrogen bonding and electrostatic interaction, was synthesized by ATRP, and its aggregation behavior in aqueous media was investigated in detail. Proton nuclear magnetic resonance spectroscopy, Fourier transform-infrared spectroscopy, and gel-permeation chromatography were performed to characterize the copolymer. Thermosensitive behaviors of the copolymers in water, NaCl, and urea solution were tracked by ultraviolet, dynamic light scattering, and transmission electron microscopy analysis. It was found that the copolymers existed as "core-shell" spheres at an elevated temperature, as a result of the self-assembly of the agarose backbones located in the "core" driven by hydrogen-bonding interactions. When the copolymer solution was cooled below UCST, the core-shell spheres began to aggregate because of the electrostatic interactions and collapse of PDMAPS side chains in the "shell" layer. UCST of the copolymer could be tuned in a wide range, depending on the chain lengths of PDMAPS. This is the first example to investigate the thermosensitivity, combining ionic interactions of the zwitterionic side chains with hydrogen bondings from the biocompatible agarose backbones. The synthetic strategy presented here can be employed in the preparation of other novel biomaterials from a variety of polysaccharides.
authors.affiliation: School of Chemical Engineering and Technology, Key Laboratory of Systems Bioengineering of Ministry of Education, Tianjin University, Tianjin 300072, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Tian
authors.forename: Jinmei
authors.initials: J
authors.lastname: Wang
authors.forename: Ershuai
authors.initials: E
authors.lastname: Zhang
authors.forename: Junjie
authors.initials: J
authors.lastname: Li
authors.forename: Cuimi
authors.initials: C
authors.lastname: Duan
authors.forename: Fanglian
authors.initials: F
authors.lastname: Yao
mesh_terms: D002850:Chromatography, Gel; D009682:Magnetic Resonance Spectroscopy; D046529:Microscopy, Electron, Transmission; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*; D012685:Sepharose / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
chemical_list: D011108:Polymers; D014867:Water; D012685:Sepharose