Generation of Thiolsulfinates/Thiolsulfonates by Electrooxidation of Thiols on Silicon Surfaces for Reversible Immobilization of Molecules

Abstract

This work describes a method for immobilization of biomolecules on surfaces via electrooxidation of surface thiols by generating thiolsulfinates/thiolsulfonates that display a high reactivity toward free thiols in molecules. This is done by applying a potential difference between a platinum cathode and a thiol-derivatized silicon surface as the anode, through a buffer solution. X-ray photoelectron spectroscopy data showed that the amount of thiolsulfinates/thiolsulfonates was voltage dependent. When a potential difference of 1.0 V was applied between the silicon surface and the platinum electrode for 1 min, about 80% of the thiols were converted to thiolsulfonates/thiolsulfinates. The results of comparative chronoamperometric experiments, using a three-electrode potentiostatic setup, indicate that the thiols are oxidized electrochemically at +0.6 V versus Ag/AgCl. This indicates the presence of a direct electrochemical oxidation of the thiols on the silicon surface rather than an oxidation of the thiols b...