A novel impedimetric nanobiosensor for low level determination of hydrogen peroxide based on biocatalysis of catalase

A robust and effective nanocomposite film-glassy carbon modified electrode based on multi-walled carbon nanotubes and a room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was prepared by a layer-by-layer self-assembly method. The fabricated modified electrode was used as a novel impedimetric catalase nanobiosensor for the determination of H2O2. Direct electron transfer and electrocatalysis of catalase were fully investigated. The results suggested that catalase could be firmly adsorbed at the modified electrode. A pair of quasi-reversible redox peaks of catalase was observed in a 0.20 M degassed phosphate buffer solution of pH 7.0. The nanocomposite film showed a pronounced increase in direct electron transfer between catalase and the electrode. The immobilized catalase exhibited an excellent electrocatalytic activity towards the reduction of H2O2. The electrochemical impedance spectroscopy measurements revealed that the charge transfer resistance decreases significantly after enzymatic reaction with hydrogen peroxide, so that the prepared modified electrode can be used for the detection of ultra traces of H2O2 (5–1700 nM).

► Preparation of an impedimetric catalase nanobiosensor for the determination of H2O2. ► Modification of a GCE with MWCNTs/[bmim][PF6]/catalase by a layer-by-layer method. ► Detailed study of direct electron transfer and electrocatalysis of catalase. ► Excellent electrocatalytic activity of immobilized catalase on reduction of H2O2. ► Electrochemical impedance spectroscopic determination of a 5 nM level of H2O2.