Investigation of direct surface modification of SAMs by electrochemistry methods

Abstract

The surface modification with various molecules is important for preparing substrates used in diagnostic assays, drug discovery, and attached cell culture. We have investgated the use of redox-active self-assembled monolayers (SAMs), containing electrochemically labile functional group, as a novel surface modification method. Thus, we synthesized the Hydroquinone monoester of 12, 12’-dithiobis(dodecanoic acid hydroquinone monoester) and constructed SAMs on gold electeode. When an electrochemical potential is applied to the SAMs, the direct substitution reactions by nucleophiles, such as amine and alcohol in the electrolyte, are readily occurred. To characterize the direct surface modification, we performed cyclic voltammetry ( CV ), X-ray photoelectron spectroscopy ( XPS ), contact angle measurement, and grazing angle FT-IR. Additionally, by using this direct modification method, we could construct a specific surface modified by biotin-PEO amine for immobilizing a streptavidin. Also, to monitor biotin-streptavidin interaction, we carried out surface plasmon resonance ( SPR ) and the biocatalytic oxidation of 4-chloro-1-naphthol by $H_2O_2$ and precipitation of 4-chloro-1-naphthone onto electrode.