Polydopamine/cysteine surface modified hemocompatible poly(vinylidene fluoride) hollow fiber membranes for hemodialysis.

Membrane surface design is significant for the development and application of synthetic polymer hemodialysis membranes. In this study, the influence of zwitterionic cysteine on poly(vinylidene fluoride) (PVDF) hollow fiber membrane was investigated. The polydopamine layer was formed through dopamine self-polymerization on PVDF membrane surface, and then cysteine was covalent grafted onto the layer to improve the anti-biofouling property and hemocompatibility. The elementary composition of membrane surfaces was characterized by X-ray photoelectron spectroscopy. The influence of polydopamine and cysteine on modified membrane surface morphologies was studied by field emission scanning electron microscopy. The modified PVDF membranes were confirmed to have excellent hydrophilicity, stable mechanical properties and good hemocompatibility (dynamic and static anti-protein adsorption, hemolysis ratio, plasma coagulation). And these properties were increased with the incorporation of polydopamine and cysteine. The optimized modified membranes exhibited high pure water flux (∼ 195.5 L/m2 h at 0.1 MPa) and selectivity (clearance ratio of urea and lysozyme was 75.1 and 55.4%, and rejection rate of bovine serum albumin was 98.8%). This work provides a surface modification method of PVDF hollow fiber membranes and suggests a potential application of PVDF membranes in hemodialysis field.