Avidin–Biotin Assembling of Horseradish Peroxidase Multi-Monomolecular Layers on Electrodes

Abstract

The strong avidin–biotin affinity is used to stack up successive monomolecular layers of horseradish peroxidase on carbon electrodes. After a biotinylated immunoglobulin is adsorbed on the electrode surface, alternate deposition of neutravidin and biotinylated HRP allows the assemblage of up to 16 successive active HRP layers. The film build-up is followed by cyclic voltammetry using an osmium complex as soluble mediator and H2O2 as substrate. The variation of the resulting catalytic responses with H2O2 concentration exhibit characteristics qualitatively consistent with the catalysis-inhibition reaction scheme previously established for monomolecular layers. In most cases the catalytic activity increases steadily with the number of monomolecular layers, leading to a significant increase of the analytical sensitivity of the derivatized electrode.