A reagentless hydrogen peroxide sensor based on incorporation of horseradish peroxidase in poly(thionine) film on a monolayer modified electrode Original Research Article

A novel reagentless hydrogen peroxide sensor fabricated by the entrapment of horseradish peroxidase (HRP) into poly(thionine) film on a thionine self-assembled monolayer modified gold electrode is described. The direct electron transfer between the heme site of HRP and the electrode is mediated by thionine units incorporated in the polymer film. The sensor displays an excellent electrocatalytic response to the reduction of H2O2. The chronoamperometric current is proportional to the H2O2 concentration in the range of 6.2 μM to 9.4 mM with a correlation coefficient of 0.999. Moreover, such a modified electrode exhibits a good stability and reproducibility within the linear range of H2O2, the variation coefficients are 3.8% and 4.5% for 10 successive assays at a H2O2 concentration of 9.3 μM and 2.8 mM, respectively.