Irreversible Low Critical Solution Temperature Behaviors of Thermal-responsive OEGylated Poly(l-cysteine) Containing Disulfide Bonds

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• 作者：Yinan Ma ; Xiaohui Fu ; Yong Shen ; Wenxin Fu ; Zhibo Li
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：July 22, 2014
• 年：2014
• 卷：47
• 期：14
• 页码：4684-4689
• 全文大小：322K
• ISSN：1520-5835

文摘

Three cysteine derivatives were synthesized in high yield by ligating monomethoxy oligo(ethylene glycol) (OEG) to l-cysteine thiol group using sulfenyl chlorides. These OEG groups containing di-, tri-, and tetra-EG units were linked with l-cysteine via disulfide bond. The three monomers were then converted into corresponding N-carboxyanhydrides (NCAs) using triphosgene in THF. Subsequent ring-opening polymerization (ROP) of disulfide bond containing NCAs gave three poly-EG_x-l-cysteine derivatives. The obtained poly-EG_x-l-cysteine with x = 3 and 4 displayed thermal-responsive behaviors in water, but the temperature-induced phase transition was found surprisingly irreversible. Such irreversible thermal-responsive behaviors were attributed to cross-linking arising from disulfide bonds exchanges. Using PEG-NH₂ as macroinitiator, we also prepared two PEG-b-poly-EG_x-l-cysteine diblocks, which could undergo irreversible thermal-induced sol鈥揼el transition, which was caused by the disulfide bonds exchanging reactions. These hydrogels displayed partially shear-thinning and rapid recovery properties allowing new capabilities to construct stimuli-responsive injectable hydrogels in biomedical applications.