A novel electrochemical biosensor for monitoring protein nitration damage affected by NaNO2/hemin/H2O2

A sensitive and facile electrochemical biosensor has been developed for monitoring the protein nitration damage affected by the nitro free radicals(NO2). The NO2 radicals is generated from hemin-catalyzed oxidation of nitrite (NO−2) in the presence of hydrogen peroxide (H2O2). In this work, nanocomposite films of graphene-gold nanoparticles (EG-AuNPs) were modified on the glassy carbon electrode by electropolymerization. Bovine serum albumin (BSA) was then further assembled on EG-AuNPs film through Au-S bond. The damage of BSA molecule was caused by the NO2 radicals which was generated from the NaNO2/hemin/H2O2 nitration reagent. The differential pulse voltammetry was used to detect the damage of BSA molecule. Fluorescence spectra and circular dichroism spectrum further confirmed the nitration damage of BSA. Moreover, the lowest concentration at which the BSA damage was detected is 28.9 µM NO−2 or H2O2, and the volume ratio of NO−2 and H2O2 was 1:1 in the hemin/NO−2/H2O2 nitration reagent. The results demonstrated that the proposed electrochemical method can be used to detect protein damage affected by nitration reagent. The developed electrochemical biosensor is envisioned to have promising applications in protein damage studies.