COMPARISON OF THE QUARTZ-CRYSTAL MICROBALANCE AND THE DOUBLE-LAYER CAPACITANCE METHODS FOR MEASURING THE KINETICS OF THE ADSORPTION OF BOVINE SERUM-ALBUMIN ONTO A GOLD ELECTRODE

The time-variations of the double-layer capacitance and of the oscillation frequency of an electrochemical quartz crystal microbalance are simultaneously recorded to determine the kinetics of adsorption of bovine serum albumin on a gold electrode. Both variations can be fitted by a sum of exponential functions. It is established that for the steps associated with a mass change both methods provide the same values for the time-constants. This result validates the double-layer capacitance measurement method, which is indirect, as a tool for determining, in situ, the kinetics of protein adsorption. Finally, it is established that, in the experimental conditions used here, the oscillation of the quartz crystal modifies, with respect to the nonoscillating quartz, the kinetics of adsorption of the macromolecules.