Grafting Hyperbranched Polylysine to Polysulfone Porous Membrane: A Promising Route for Modulating Membrane Multi‐Properties

ABSTRACT The inherent hydrophobicity of ultrafiltration membranes facilitates organic contaminant adsorption and microbial colonization through hydrophobic interactions, significantly reducing separation efficiency and operational lifespan due to irreversible fouling and structural degradation. To address this pressing problem, this study grafts hyperbranched polylysine (HBPL) onto the surface of polysulfone ultrafiltration (PSF UF) membranes via solid–liquid interface aminolysis. This innovative approach significantly enhances the hydrophilicity of the membrane surface while endowing the membrane with robust antibacterial properties. The results indicate that the modified PSF/HBPL membranes (the HBPL content 4.6 μg cm −2 ) present lower BSA adhesion (40.5% of the original PSF membrane) and higher flux recovery (79.6%) compared with the original PSF UF membrane. Additionally, the modified membranes are demonstrated to exhibit effective broad‐spectrum antibacterial activity (94.8% against E. coli and 95.2% against S. aureus ). Furthermore, the in vitro hemolytic activity assay and cytocompatibility test confirm their non‐toxicity and good biocompatibility. By controlling the surface grafting density of HBPL, a hydrophilic contact‐killing surface with hydration repulsion has been obtained, achieving synergistic antibacterial and anti‐protein adhesion activity. The method of membrane fabrication employed in this study was found to be convenient and low cost, suggesting its significant potential for application in practical settings.