Zwitterionic/active ester block polymers as multifunctional coatings for polyurethane-based substrates

Bacterial-associated infection, blood coagulation, and tissue adhesion are severe issues associated with biomedical implants and devices in clinic applications. Here, we report a general strategy to simultaneously tackle these issues on polyurethane (PU)-based substrates. Taking advantage of reversible addition-fragmentation chain transfer (RAFT) polymerization, well-defined zwitterionic/active ester block polymers (pSBMA-b-pNHSMA) with an identical pNHSMA segment (polymerization degree of 15) but varied zwitterionic pSBMA segments (polymerization degrees of 40 and 100) were precisely prepared. The pSBMA-b-pNHSMA block polymers could be easily covalently constructed on PU substrates that were pretreated with a polydopamine coating based on highly efficient anime-active ester chemistry, as evidenced by the water contact angle and XPS tests. The relationship between the length of pSBMA segments in the coating and the antifouling ability of PU substrates was established. The results indicated that block polymers with a pSBMA segment of 40 repeat units could significantly prevent protein adsorption, bacterial/platelet adhesion, and cell attachment on PU substrates within 24 h, while a longer pSBMA segment (repeat units of 100) could endow long-term antibacterial (14 days without biofilm formation) and anti-cell attachment (5 days without cell attachment) properties to the PU substrates. Furthermore, the coating significantly improved the surface lubricating property of PU substrates without compromising on the mechanical property. This strategy may find many applications in PU-based implants and devices.