PNNL

Abstract

A new approach to construct a reagentless H2O2 electrochemical sensor is described. Iron oxide magnetic nanocystals (IOMNs), as peroxidase mimetics, were employed to assemble a multilayer structure layer by layer. Polythionin was electrodeposited onto the glassy carbon electrode surface to introduce amino groups. Carboxyl functionalized multi-walled carbon nanotubes, amino functionalized IOMNs, and thionin monomers were anchored onto a polythionin-functionalized GC surface in order by carbodiimide or glutaraldehyde chemistry. The resulting multilayer construction with three layers of IOMNs and thionin mediator exhibits excellent electrochemical response to the reduction of H2O2, whereas such a modified electrode with one layer construction only yields a slight response to H2O2 of the same concentration. The tethered MWCNs enlarge the amount of immobilized IOMNs and effectively shuttle electrons between the electrode and the thionin.