A robust mixed-charge zwitterionic polyurethane coating integrated with antibacterial and anticoagulant functions for interventional blood-contacting devices

Antifouling coatings based on zwitterionic polymers have been widely applied for surface modification of interventional blood-contacting devices to combat thrombosis and infection. However, the weak adhesion stability of the zwitterionic coating to the device surface is still the key challenge. In this work, biocompatible mixed-charge zwitterionic polyurethane (MPU) polymers, that bear equal amounts of cationic quaternary amine groups and anionic carboxyl groups, were developed and further uniformly dip-coated onto a thermoplastic polyurethane (TPU) substrate with a commercial aliphatic isocyanate cross-linker (AIC). During the curing process, AIC not only crosslinks MPU chains into a polymer network but also reacts with hydroxyl groups of TPU to interlink the polymer network to the substrate, resulting in a cross-linking reinforced MPU coating (CMPU) with excellent mechanical robustness and adhesion strength. Taking advantage of the mixed-charge feature, the final zwitterionic CMPU coating exhibits both excellent antifouling and antibacterial activities against protein adsorption and bacterial growth, respectively, which is beneficial for effectively inhibiting the occurrence of in vivo infection. Moreover, anticoagulation studies show that CMPU-coated TPU catheters can also prevent the formation of blood clots in ex vivo rabbit blood circuits without anticoagulants. Hence, the designed CMPU coating has immense potential to address thrombosis and infection for interventional blood-contacting devices.