Thiol Click Modification of Cyclic Disulfide Containing Biodegradable Polyurethane Urea Elastomers

Although the thiol Click reaction is an attractive tool for postpolymerization modification of thiolmers, thiol groups are easily oxidized, limiting the potential for covalent immobilization of bioactive inclecules. In this study, a series of biodegradable polyurethane elastomers incorporating stable cyclic disulfide groups Was developed and characterized: Thee poly(ester urethane)urea (PEUU-SS)- polymers were based on polycaprolactone,diol (PCL), oxidized DL-dithiothreitol (O-DTT), lysine diisocyanate or butyl diisocyanate (BDI), with, chain extension by putrescine. The,ratio, of O-DTT:PCL was altered to investigate different levels of potential functionalization. PEG acrylate was employed to study the mechanism and availability of both bulk and surface click modification of PEUU-SS polymers. All synthesited-PEUU-SS polymers were elastic with breaking strengths of 38-45 MPa, while the PEUU-SS (LDI) polymers were more amorphous, possessing lower moduli and relatively small permanent deformations versus PEUU-SS(BDI) polymers. Variable bulk click modification of PEUU-SS(LDI) polymers was achieved by controlling the amount of reduction. reagent, and rapid reaction rates occurred using a one-pot, two-step process. Likewise, surface click reaction could be carried out-quiCkly-under mild, aqueous conditions. Furthermore, a malennide-modified affinity peptide (TPS) was successfully clicked on the surface of an electrospun PEUU-SS(BDI) fibrous sheet, which improved endothelial-progenitor cell adhesion versus corresponding unmodified films. The cyclic disulfide containing biodegradable polyurethanes described provide an option for cardiovascular and Other soft tissue regenerative medicine applications where a temporary, elastic scaffold with designed biofunctionality from a relatively simple click chemistry approach is desired.