Si Doped CoO Nanorods as Peroxidase Mimics for Colorimetric Sensing of Reduced Glutathione

Si doped CoO nanorods (denoted as Si-CoO) were prepared by the hydrothermal method. The Si-CoO composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectra (XPS), etc. The results suggest that Si element uniformly distributed onto CoO nanorods with a diameter of 50-100 nm. The as prepared Si-CoO nanocomposite possessed an excellent peroxidase-like activity as well as quickly catalyzed the colorless substrate 3,3,5,5-tetramethylbenzidine (TMB) to be oxidized into blue oxTMB by H2O2 only in 20 s, which was easily visually observed. The electron spin resonance (ESR) data confirms that superoxide radicals (center dot O-2(-)) play a key function in catalytic reaction. On the basis of the peroxidase biomimetic activity of Si-CoO, we constructed a new biosensor for detection of H2O2 and reduced glutathione (GSH) in the range of 1-100 uM with a limit of 0.22 and 0.45 uM, respectively.