Adsorption-selectivity customization and competitive adsorption of tryptamine-based mixed-mode chromatography

Abstract

Mixed-mode chromatography (MMC) shows great promise for applications in protein purification. Therefore, novel MMC ligands are always desired. However, achieving high adsorption selectivity of ligands is a major challenge due to competitive adsorption. Herein, MMC with tryptamine (4 F F-TA) exhibited equal adsorption capacity for bovine serum albumin (BSA) and bovine immunoglobulin (bIgG), affording a unique competitive adsorption process, but non ideal purity. Molecular imprinting technology (MIT) was adopted for the customized adsorption selectivity of MMC, and BSA and bIgG were used as imprinting templates. Static and dynamic binding performances under competitive adsorption before and after imprinting were investigated at different pH values, salt concentrations, and BSA/bIgG mass ratios. The results showed that the adsorption capacity of the target protein remained similar level but competitive protein adsorption dropped significantly (below 40 mg/g resin). This indicated that the adsorption selectivity of 4 F F-TA could be customized by changing the template protein used during imprinting. In addition, the pH-dependence and salt tolerance of MMC were unchanged after imprinting. The binding behaviors of BSA and bIgG in column chromatographic separation further confirmed the improved in adsorption selectivity. The purity of BSA increased from 55.4% to 78.2% for 4 F F-TA@BSA and that of bIgG from 40.7% to 71.2% for 4 F F-TA@bIgG. This study indicated that MIT is an effective strategy to change and improve the adsorption selectivity of MMC.