2000 Volume 16 Issue 8 Pages 799-805
The adsorption of lysozyme from phosphate-buffered saline (pH 7.4) onto bare and cysteine- or 1-octadecanethiol-modified Au electrodes was investigated in situ using an electrochemical quartz-crystal impedance system (EQCIS). The equivalent circuit parameters and resonant frequencies of the piezoelectric quartz-crystal (PQC) resonance, the value of half peak width of the electroacoustic conductance spectrum (DfG1/2) as well as the electrical double-layer capacitance were obtained and analyzed. The adsorption kinetics was analyzed with a scheme of two consecutive reactions occurring at the interface. The amount of adsorbed lysozyme on a hydrophobic surface was greater than that on a hydrophilic one, and a more negative potential brought a larger amount of adsorbed lysozyme. The standard heterogeneous rate constants of ferricyanide/ferrocyanide before and after the lysozyme adsorption were evaluated.
