Investigating dialysis membrane surface charge and hydrophobicity effects on fibrinogen adsorption using synchrotron radiation micro-computed tomography (SR-CT)

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Hemodialysis, a critical treatment for end-stage kidney disease (ESKD), efficiently eliminates toxic metabolic waste from the bloodstream. This study probes the complex interactions among surface charge, wettability, and roughness of Polyethersulfone (PES) membranes and their influence on fibrinogen (FB) adsorption, a key culprit in membrane fouling that compromises the dialysis efficacy. Utilizing non-invasive X-ray synchrotron-based micro-tomography (SR-CT), we analyzed an array of PES membranes—ranging from unmodified to superhydrophobic surfaces achieved via surface hydrophobization or hydrophobic mixed matrix methods, heparin-immobilized versions, zwitterionically coated with sulfobetaine and carboxibetaine, and uremic metabolite-modified membranes, each with intensified coatings. Our findings highlight that superhydrophobic membranes, particularly hydrophobic mixed matrix membrane, significantly repel FB, reducing fouling due to their high contact angle. Additionally, membranes with lower surface charges corresponded with lower protein adsorption, emphasizing the pivotal role of electrostatic interactions. Intriguingly, hydrophobic membranes outperformed their hydrophilic counterparts despite having higher surface roughness, suggesting that peak hemodialysis membrane performance is achieved through a synergistic balance of reduced surface charge and enhanced hydrophobicity. These insights drive home the importance of integrating charge, wettability, and texture considerations in membrane design to foster the next generation of low-fouling, high-performance hemodialysis membranes.