In vitro elimination of protein bound uremic toxin p-cresol by MFI-type zeolites

The removal of uremic toxins by zeolites is investigated in the context of the exploration of alternative methods to blood purification by dialysis. The case of a partially protein bound molecule, p-cresol, is studied here. High silica MFI type zeolites show a selective adsorption for p-cresol without major ion exchange with the cations present under equilibrium conditions in solution. Adsorption isotherms in different media were performed: pure water, artificial blood serum containing bovine serum albumin and human serum (HS obtained from a pool of 50 dialysis patients). p-Cresol elimination levels of 80-85% were obtained under in vitro conditions. However, in HS, p-cresol affinities for the zeolites are generally reduced as compared with pure water due to a partial obstruction of the pore system by adsorption of proteins on the external surface of zeolites particles. These results show that zeolites can be successfully employed as specific adsorbents for uremic toxins but without direct contact with serum albumin, which means only in the ultra-filtrate. (C) 2011 Elsevier Inc. All rights reserved.