In Situ Self Assembly of Thiolated ortho-Quinone Capped Electrocatalysts for Bioanalytical Applications

Thiolated o-quinone-capped electrocatalysts modeled on the naturally occurring o-quinone cofactor pyrroloquinoline quinone (PQQ) were designed and synthesized for the development of biosensor devices. The o-quinone-capped electrocatalysts self assembled on gold electrodes through a thiolated phenyleneethynylene linkage to form a monolayer less than 2nm in thickness. Cyclic voltammetric measurements demonstrated reversible electrochemical properties between the quinone and hydroquinone forms of the head group. In an amperometric sensing mode, the modified electrodes reproducibly detected ethanethiol at micromolar levels demonstrating their robust electrocatalytic activity toward thiols. Their redox cycling and electrocatalytic properties show promise for detection of biologically important thiols and other nucleophiles.