Direct electrochemistry of Cytochrome c on natural nano-attapulgite clay modified electrode and its electrocatalytic reduction for H2O2

Natural nano-structural attapulgite clay was purified by mechanical stirring with the aid of ultrasonic wave and its structure and morphology was investigated by XRD and transmission electron microscopy (TEM). Cytochrome c was immobilized on attapulgite modified glassy carbon electrode. The interaction between Cytochrome c and attapulgite clay was examined by using UV–vis spectroscopy and electrochemical methods. The direct electron transfer of the immobilized Cytochrome c   exhibited a pair of redox peaks with formal potential (E0′)(E0′) of about 17 mV (versus SCE) in 0.1 mol/L, pH 7.0, PBS. The electrode reaction showed a surface-controlled process with the apparent heterogeneous electron transfer rate constant (ks) of 7.05 s−1 and charge-transfer coefficient (α) of 0.49. Cytochrome c immobilized on the attapulgite modified electrode exhibits a remarkable electrocatalytic activity for the reduction of hydrogen peroxide (H2O2). The calculated apparent Michaelis–Menten constant (Kmapp) was 470 μmol/L, indicating a high catalytic activity of Cytochrome c immobilized on attapulgite modified electrode to the reduction of H2O2. Based on these, a third generation of reagentless biosensor can be constructed for the determination of H2O2.