In situ zwitterionic hydrogel coating of hollow fiber membranes for anti-fouling and efficient hemodialysis

Protein adsorption and biofouling during hemodialysis cause flux decline and reduced toxin removal, thereby shortening membrane lifetime and compromising treatment safety. Here, a thermally initiated interfacial polymerization strategy is developed to construct a zwitterionic hydrogel antifouling layer on the lumen surface of polyethersulfone hollow fiber membranes. Structural and chemical characterizations show that the structure and composition of the hydrogel layer can be tuned by monomer concentration. In situ visualization using a single-fiber-on-a-chip microfluidic platform reveals that the hydrogel coating suppresses protein adsorption, while maintaining small-molecule transport and reducing fouling-induced deterioration of middle-molecule diffusion. In vitro recirculating dialysis experiments confirm that hydrogel-coated dialyzers maintain stable water flux under repeated fouling, while sustaining effective clearance of small- and middle-molecular-weight solutes in a simulated dialysis environment. Moreover, extracorporeal circulation studies in a beagle dog model under low-anticoagulation conditions show that hydrogel-coated dialyzers achieve improved clearance and reduced fouling over a 4-h dialysis treatment compared to commercial dialyzers. Overall, this work demonstrates a strategy of lumen-side hydrogel interface engineering to enhance solute clearance performance under biofouling conditions, providing a potential route toward antifouling and biocompatible hemodialysis membrane materials. © 2026 Elsevier B.V.