Intercalation of methylene blue into layered manganese oxide and application of the resulting material in a reagentless hydrogen peroxide biosensor

Methyleneblue (MB) has been intercalated into layered manganese oxide (birnessite)by a delamination/reassembly process and the resulting MB-intercalated birnessite (MB-Bir) material characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and electrochemical measurements. A novel reagentless hydrogen peroxide biosensor was fabricated by using the MB-Bir as an electron mediator. Cyclic voltammetry and amperometric measurements demonstrated that methylene blue coimmobilized with horseradish peroxidase (HR-P) displayed good stability and that electrons were efficiently shuttled between HRP and the electrode. The biosensor showed a rapid and linear response to H2O2 over the range from 1.5 x 10(-6) M to 8.1 x 10(-3) M, with a detection limit of 1.3 mu M (S/N = 3/1). Moreover, the biosensor retained about 85% of its original response to H2O2 after storage for 2 months. Addition of glucose, sucrose, citric acid, acetic acid, or L-ascorbate did not interfere with the H2O2 response. (C) 2007 Elsevier B.V. All rights reserved.