Zwitterion Functionalization of Polyurethanes via Thiol-ene Click for Antifouling Surfaces—Lessons from Nature

Inspired by the phospholipids on cell membranes, zwitterionic groups have been widely studied for their antifouling property. Equipped with two oppositely charged groups in the same moiety, zwitterions exhibit properties like super hydrophilicity through ionic solvation and tightly bound hydration layer that enables non-specific protein resistance. Additionally, zwitterionic materials also enhance biocompatibility and reduce immune response.<br/>Catheter-associated infections (CAIs) have one of the highest mortality rates among healthcare-associated infections. Besides being a major cause of morbidity and mortality, CAIs also impose a heavy financial burden resulting from prolonged treatment and hospital stays. Increasing cost and health related complications necessitate the research for improving currently employed biomaterials for catheter applications. Creating antifouling surfaces by immobilizing zwitterion molecules on material surfaces has been proved to be a promising strategy. Herein, we investigated zwitterion surface-functionalized thermoplastic polyurethane (TPU) for use in antifouling catheter. The thermoplastic polyurethane was synthesized to have an allyl ether side functionality. Zwitterion surface-functionalization was achieved <i>via</i> thiol-ene ‘click’ chemistry in aqueous conditions. The XPS results confirmed the presence of chemically tethered zwitterion moieties on the zwitterion-TPU surface. The Quartz crystal microbalance (QCM) results show reduced fibrinogen attachment for the zwitterion-TPU when compared to its unfunctionalized controls. The zwitterion-TPU also showed a log scale reduction in bacterial adherence. For <i>P. aeruginosa and S. epidermidis,</i> the zwitterion-TPU resulted in around a 40% and 50% lower bacterial biomass accumulation, respectively. The fibroblast cell viability of TPU remained unaffected by functionalization with zwitterion thiol. Our results suggest a zwitterion modified TPU is a promising candidate for antifouling catheters.