Electrochemistry of surface wired cytochrome c and bioelectrocatalytic sensing of superoxide

Abstract

Electrochemistry of cytochrome c (Cyt-c) wired on an electrode modified with the self-assemblies of 4,4′-dithio-dibutyric acid (DTB) and 2-pyrazineethane thiol (PET) by covalent and electrostatic binding and the amperometric sensing of superoxide (O\(_{2}^{-})\) are described. Cyt-c wired on the mixed self-assembly of DTB and PET displays well-defined voltammetric response at 0.025 V with a peak-to-peak separation (ΔE p ) of 5 mV. Pyrazine unit in the mixed self-assembly promotes the electron transfer in the redox reaction of surface wired Cyt-c. Cyt-c wired on the mixed self-assembly has been used for the amperometric sensing of superoxide. The enzymatically generated superoxide has been successfully detected using the Cyt-c wired electrode. High sensitivity and fast response for superoxide have been achieved. Uric acid does not interfere in the amperometric measurement of superoxide. The interference due to H2O2 has been eliminated by using enzyme catalase. Wiring of cytochrome c on the mixed self-assembly of 4,4’-dithio-dibutyric acid and 2-pyrazineethane thiol and the amperometric sensing of superoxide are described.