Designing adsorptive membranes for removing protein-bound uremic toxins via π-π and cation-π interaction

Protein-bound uremic toxins (PBUTs) are recently thought to critically influence overall organ dysfunction, morbidity, and mortality of chronic kidney disease (CKD) patients. However, traditional hemodialysis and/or hemoperfusion processes fail to remove PBUTs efficiently due to their strong affinity with albumins. Herein, we fabricated a novel adsorptive membrane incorporating amine/polyphenol/bimetal ions complexation in the polysulfone membrane substrate, which has a higher affinity with hippuric acid, p-cresol sulfate, and indoxyl sulfonate. The complexation is a synergy of polyelectrolyte (polyethyleneimine-tannic acid) and metal-phenolic (tannic acid/metals) networks. The adsorption behavior of those three uremic toxins on the optimized adsorptive membrane was investigated by kinetic and adsorption isotherm studies. From X-ray photoelectron spectroscopy analysis assisted by Fourier transform infrared reflection spectrum, we attribute the high adsorption capacity to π-π and/or cation-π interaction with aromatic ring groups of uremic toxins. The adsorptive membrane could effectively remove albumin bounded uremic toxins and water-soluble urea through a continuous dialysis process. Besides, the membrane showed excellent hemocompatibility and minimized immune responses by suppressing complement activation. The above results showed the potential clinical application of adsorptive membranes.