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 (O₂^- 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.