Monitoring for adsorption of human serum albumin and bovine serum albumin onto bare and polystyrene-modified silver electrodes by quartz crystal impedance analysis

The adsorption of human serum albumin (HSA) and bovine serum albumin (BSA) from PBS (pH 7.4) onto bare and polystyrene (PS)-modified silver electrodes was in situ monitored using quartz crystal impedance analysis. The adsorpt ion characteristics of HSA and BSA were discussed by analyzing piezoelectri c parameter simultaneous responses. Experimental results indicated that for both HSA and BSA, the amount adsorbed on bare silver was more than that on PS-modified surface. The BSA amount adsorbed on the two surfaces was more than that of adsorbed HSA. A kinetic model was developed to describe the ad sorption process and fitted to the experimental data of frequency shift. It was shown that HSA adsorption could be described by a kinetic equation inv olving two consecutive reactions. At lower concentration, BSA adsorption on ly involved the first reaction. At higher concentration, BSA adsorption on PS-modified surface involved two consecutive reactions. All fitted results were well in agreement with the corresponding experimental results. The reg ression values of reaction rate constants for the HSA and BSA adsorption we re obtained. These data exhibited difference in adsorption kinetics under d ifferent conditions. (C) 2001 Elsevier Science Ltd. All rights reserved.