Thiol-ene photopolymerizations for the synthesis of bioresponsive, bioinstructive hydrogels

     To support cell motility and matrix deposition, it is often desirable to incorporate a mechanism for enzymatic degradation into synthetic hydrogels but the irregular network structure of radically polymerized di(meth)acrylate hydrogels limits control of the gel erosion profile and leads to a broad distribution of molecular weight degradation products.  Thiol-ene photopolymerization (a radical-mediated step-growth polymerization) provides means to incorporate proteolytically cleavable peptides into a highly regular gel network structure.  Thiol moieties on cysteine-containing peptides react with allyl ether end-groups on a multi-arm PEG monomer in 1:1 ratio of functionalities.  Because the polymerization is initiated with light, physiological reaction conditions, temporal and spatial control are all realized.