Electrochemically reduced graphene oxide modified with electrodeposited thionine and horseradish peroxidase for hydrogen peroxide sensing and inhibitive measurement of chromium

Abstract

Fabrication of hydrogen peroxide (H2O2) biosensor for determination of Cr(VI) based on the inhibition of horseradish peroxidase (HRP) activity is reported herein. The sensor platform was developed by using electrochemically reduced graphene oxide (ERGO) film modified GCE electrode. The thionine layer is deposited over ERGO layer by two step electrodeposition process. Immobilization of HRP over the thionine modified ERGO electrode has been done by mixing with bovine serum albumin (BSA) and using glutaraldehyde as a crosslinker. The cathodic responses of the immobilized HRP for H2O2 detection is monitored using cyclic voltammetry and linear sweep voltammetry method. Cr(VI) as a trace metal ions inhibitor to the enzyme activity was proportional to concentration in the range of 0.039–0.78 µM with the sensitivity of 4.41% inhibition µM−1 and the limit of detection is 0.02 µM (S/N = 3). The inhibition mechanism determined from Dixon and Cornish-Bowden plots was found to be uncompetitive. Good stability and reproducibility of the developed sensor could provide an excellent sensing platform for the determination of peroxide and heavy metals in environmental analyses and clinical testing.