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.

Quaternized poly(2-(dimethylamino)ethyl methacrylate)-grafted agarose copolymers for multipurpose antibacterial applications

“…26,30 It has been reported that the hydroxyl groups at the C-6 positions of polysaccharides are apparently favorable for the substitution reactions. In this work, the bromoisobutyryl-functionalized Agr (Agr-Br) macroinitiator was prepared via the reaction of hydroxyl groups of Agr with 2bromoisobutyryl bromide (BiBB) (Scheme 1).…”

“…22 Due to its biocompatibility, non-fouling and non-immunogenic attributes, 23 Agr has been widely explored for applications in the biomedical eld. 23,24,26,27 Thus, integration of Agr and QAS could lead to the formation of an antibacterial agent, which is soluble in aqueous media at low concentration and solidies as a hydrogel at high concentration. Agr is soluble/dispersible in aqueous media at a lower concentration.…”

Structures and Synthesis of Zwitterionic Polymers

“…RDRP techniques offer direct access to polymers bearing zwitterionic groups with previously unthinkable features, such as predefined molar masses and narrow molar mass distributions [163,[182][183][184][185][186][187][188][189] as well as well-defined functional end groups [61,166,182,[190][191][192][193][194][195][196][197][198][199][200][201][202][203][204][205][206][207][208]. Moreover, complex architectures, such as block copolymers [14,[46][47][48]166,167,169,173,187,, graft copolymers [164,213,237,[241][242][243][244]…”

Self‐assembled UCST‐Type Micelles as Potential Drug Carriers for Cancer Therapeutics

“…As observed under TEM, the amphiphilic copolymers still formed spherical micelles at same concentration (Figure S5b, Supporting Information). It was believed that the introduction of hydrophilic PEG segment into the block copolymer may weaken the interactions between P(AAm‐ co ‐AN) segments, resulting in decreased UCST …”

“…It was believed that the introduction of hydrophilic PEG segment into the block copolymer may weaken the interactions between P(AAm-co -AN) segments, resulting in decreased UCST. [ 20,31 ] The effect of polymer concentration on the UCST of the P5 was studied at micelle concentration of 0. (Figure 2 c).…”