Construction of electro-neutral surface on dialysis membrane for improved toxin clearance and anti-coagulation/inflammation through saltwater fish inspired trimethylamine N-oxide (TMAO)

Dialysis membranes capable of preventing coagulation and inflammation and achieving high toxin clearances are highly desired for clinical hemodialysis. Here, we constructed an electro-neutral and hydrophilic surface on Polysulfone (PSf) membrane, which both improved the hemocompatibility and toxin clearance. The membrane surface was modified with trimethylamine N-oxide (TMAO) through Michael addition reaction and subsequent crosslinking with glycidyl ether oxypropyl trimethoxysilane (KH560). Saltwater fish inspired zwitterionic monomer TMAO without spacers between positive and negative headgroups is thought to generate a hydrated and net-charged layer that prevents non-specific plasma proteins and platelets adsorption and activation. Coagulation time, serine protease Factor XIIa, bradykinin (BK), kallikrein (KLK) and anaphylatoxins (C3, C5 and SC5b-9) were examined to explore blood compatibility. All results showed that the highly hydrated and electro-neutral surface could efficiently alleviate the activation of the coagulation cascade, kallikrein-kinin system (KKS) and complement system simultaneously. Furthermore, the modified PSf membrane is favorable to toxins clearance (e.g., urea, creatine, lysozyme and vitamin B12) during simulated dialysis process. It is manifested that the TMAO based surface modification is feasible for improving the hemocompatibility and toxin clearance of dialysis membranes.