A fast and versatile cross-linking strategy via o-phthalaldehyde condensation for mechanically strengthened and functional hydrogels

• 作者: Zhen Zhang Chaoliang He Yan Rong Hui Ren Tianran Wang Zheng Zou Xuesi Chen
• 来源期刊: 国家科学评论（英文版）
• 年，卷（期）: 2021,（4）
• 所属期刊栏目: RESEARCH ARTICLES
• 页码范围: 109-119
• 页数: 11页
• 语种: 英文
• DOI: 10.1093/nsr/nwaa128

摘要

Fast and catalyst-free cross-linking strategy is of great significance for construction of covalently cross-linked hydrogels.Here,we report the condensation reaction between o-phthalaldehyde (OPA) and N-nudeophiles (primary amine,hydrazide and aminooxy) for hydrogel formation for the first time.When four-arm poly(ethylene glycol) (4aPEG) capped with OPAwas mixed with various N-nudeophile-terminated 4aPEG as building blocks,hydrogels were formed with superfast gelation rate,higher mechanical strength and markedly lower critical gelation concentrations,compared to benzaldehyde-based counterparts.Small molecule model reactions indicate the key to these cross-links is the fast formation ofheterocycle phthalimidine product or isoindole (bis)hemiaminal intermediates,depending on the N-nucleophiles.The second-order rate constant for the formation ofphthalimidine linkage (4.3 M-1 s-1) is over 3000 times and 200 times higher than those for acylhydrazone and oxime formation from benzaldehyde,respectively,and comparable to many cycloaddition dick reactions.Based on the versatile OPA chemistry,various hydrogels can be readily prepared from naturally derived polysaccharides,proteins or synthetic polymers without complicated chemical modification.Moreover,biofunctionality is facilely imparted to the hydrogels by introducing amine-beating peptides via the reaction between OPA and amino group.