Surface Modification of Polycarbonate Urethane with Zwitterionic Polynorbornene via Thiol-ene Click-Reaction to Facilitate Cell Growth and Proliferation

Herein, we grafted the zwitterionic polynorbornene onto polycarbonate urethane (PCU) film surface by a convenient route of thiol-ene click-chemistry. The PCU film surface was first treated with hexamethylene-1,6-diisocynate and subsequently with two different thiol agents (L-cysteine and beta-marcaptoethanol) in the presence of di-n-butyltin dilaurate (DBTDL) to immobilize sulfhydryl groups onto the surface. Here, DBTDL acted as selective catalyst for the reaction between surface-tethered isocyanates and amine/hydroxyl groups in thiol agents over that of free thiol groups. In the next step, zwitterionic polynorbornene (poly(NSulfoZI)) having functionalizable double bonds was grafted onto these surfaces by photo-initiated thiol-ene click-reaction. The modified surfaces were characterized by water contact angle and XPS analysis. Moreover, the cytocompatibility of these surfaces was investigated by model endothelial cells, EA.hy926, for 1, 3, and 7 d culture times, which showed enhanced cell adhesion and growth. Therefore, the poly(NSulfoZI) functionalized PCU surface using l-cysteine as thiol agent could be a good candidate for tissue engineering material application.