The stability of enamine crosslinks formed from acetoacetate/amine in synthetic hydrogels

Functional pH-responsive polymers containing dynamic enaminone linkages for the release of active organic amines

Dynamic covalent bonds have attracted attention for the development of pH-responsive polymers, however, studies using acid-cleavable enaminone linkages as a means of controlled drug release have been limited. Herein, we...

Synthetic hydrogels formed by thiol-ene crosslinking of vinyl sulfone-functional poly(methyl vinyl ether-alt-maleic acid) with α,ω-dithio-polyethyleneglycol

Polymer hydrogels formed by rapid thiol-ene coupling of macromolecular gel formers can offer access to versatile new matrices. This paper describes the efficient synthesis of cysteamine vinyl sulfone (CVS) trifluoroacetate, and its incorporation into poly(methyl vinyl ether-alt-maleic anhydride) (PMMAn) to form a series of CVS-functionalized poly(methyl vinyl ether-alt-maleic acid) polymers (PMM-CVS_x) containing 10 to 30 mol% pendant vinyl sulfone groups. Aqueous mixtures of these PMM-CVS and a dithiol crosslinker, α,ω-dithio-polyethyleneglycol (HS-PEG-SH, M_n = 1 kDa), gelled through crosslinking by Michael addition within seconds to minutes, depending on pH, degree of functionalization, and polymer loading. Gelation efficiency, Young's modulus, equilibrium swelling and hydrolytic stability are described, and step-wise hydrogel post-functionalization with a small molecule thiol, cysteamine, was demonstrated. Cytocompatibility of these crosslinked hydrogels towards entrapped 3T3 fibroblasts was confirmed using a live/dead fluorescence assay.