Estimation of Kinetics Parameters for the Adsorption of Human Serum Albumin onto Hydroxyapatite-modified Silver Electrodes by Piezoelectric Quartz Crystal Impedance Analysis

Abstract

The adsorption of human serum albumin onto hydroxyapatite-modified silver electrodes has been in situ investigated by utilizing the piezoelectric quartz crystal impedance technique. The changes of equivalent circuit parameters were used to interpret the adsorption process. A kinetic model of two consecutive steps was derived to describe the process and compared with a first-order kinetic model by using residual analysis. The experimental data of frequency shift fitted to the model and kinetics parameters, k₁, k₂, ψ₁, ψ₂ and q_r, were obtained. All fitted results were in reasonable agreement with the corresponding experimental results. Two adsorption constants (7.19 kJ mol^-1 and 22.89 kJ mol^-1) were calculated according to the Arrhenius formula.