Affinity Capillary Electrophoresis Based on Receptor Quasi-Immobilization for the Study of Interactions Between Drugs and Serum Albumin

Herein, a receptor quasi-immobilization affinity capillary electrophoresis strategy was developed for the first time, using metal–organic frameworks with bio-macromolecular loading capacity and excellent separation performance, and for the efficient and accurate determination of the interactions between drugs and serum albumin. As a proof-of-concept demonstration, bovine serum albumin was used as the receptor, and zeolitic imidazole framework-8, a metal–organic framework with good biocompatibility and separation performance, was utilized as the chromatographic stationary phase as well as the substrate for the quasi-stationary phase of protein to investigate the interactions between bovine serum albumin and sulfonamides. Relying on the separation capability of the capillary chromatographic column and the extension of the migration time window by the quasi-immobilized receptor, the binding constants between three sulfonamide drugs and bovine serum albumin were successfully determined. The result was sulfadiazine > sulfadimethoxine > sulfaquinoxaline sodium, which was consistent with those obtained by fluorescence spectrometry and traditional affinity capillary electrophoresis. Furthermore, the binding constants of chiral drugs (omeprazole sodium and D, L-tryptophan) with human serum albumin were successfully determined by applying the capillary electrochromatographic column that had been rinsed with acetonitrile solution. In summary, the method not only enables the simultaneous evaluation of interaction between ligands and a protein within a complex system but also allows the investigation of interactions between different biomacromolecules and multicomponent systems through the substitution of quasi-immobilized receptors. Consequently, the present study provides a novel way to facilitate the rapid and accurate screening of active constituents within complex systems.