Poly(styrene-alt-maleic anhydride)-copolymers blended in poly(ether sulfone) membranes as a platform for effective biomolecular surface functionalization

Endowing membranes with specific properties, often requires surface functionalization. However, coating processes are frequently time-consuming, expensive and limited in stability. Therefore, low-cost alternatives that offer a wide range of surface functionalization options are sought. This work presents poly(ether sulfone)/poly(vinyl pyrrolidone) (PES/PVP) membranes with blended poly(styrene-alt-maleic anhydride) (SMA)-copolymers, which covalently bind amine groups on the surface. Using this approach, an anchoring point for variable subsequent membrane functionalization with amine-bearing molecules was established and applied for an anticoagulant membrane decoration with heparin to increase the hemocompatibility of the membrane surface. Membranes prepared from PES/PVP polymer solution exhibited a stable integration of 0.05 to 0.5 wt.% SMA-copolymer in the membrane structure, both in buffer systems and biofluid. Zeta potential and fouling measurements showed a strong influence of the SMA-copolymers with decreased binding of albumin onto the membrane surface, while no significant change in morphology was detected for SMA-copolymer blended flat sheet and hollow fiber membranes. For further immobilization with aminated molecules, the reactive maleic anhydride groups were freshly activated by tempering, and functionalization occurred from an aqueous solution. The covalent binding was first validated using an amine-bearing fluorescence label, thereby showing the highest binding for membranes blended with 0.1 wt.% SMA-copolymer. The potential of this functionalization platform was demonstrated by immobilization of aminated heparin for application as hemodialysis membranes. The heparin exhibited bioactivity on the membrane surface, while the mechanical properties were comparable to the reference membranes. Overall, the presented system offers a simple and cost-effective technology for a stable membrane functionalization with a broad range of applications.