NiO nanoparticles modified with 5,10,15,20-tetrakis(4-carboxyl pheyl)-porphyrin: promising peroxidase mimetics for H2O2 and glucose detection.

NiO nanoparticles (NPs) and 5,10,15,20-tetrakis(4-carboxyl pheyl)-porphyrin (H2TCPP) functionalized NiO nanoparticles (H2TCPP-NiO nanocomposites) have been prepared by a facile method and characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FTIR), respectively. NiO NPs and H2TCPP-NiO nanocomposites have been proven to function as peroxidase mimetics that can catalyze the reaction of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue color reaction. Kinetic analysis indicated that the catalytic behavior was in accord with typical Michaelis-Menten kinetics. And these nanoparticles also exhibited strong affinity for the substrates of 3,3,5,5-tetramethylbiphenyl dihydrochloride (TMB). Experimental results showed that H2TCPP-NiO NPs exhibited a high sensitivity and a low detection limit towards H2O2 (8.0 × 10(-6) M). The H2TCPP-NiO NPs/glucose oxidase (GOx)/TMB system provides a novel colorimetric sensor for glucose and shows good response toward glucose detection over arrange of 0.05-0.50 mM with a limit of detection 2.0 × 10(-5)M. Fluorescence probe experiments demonstrated that the peroxidase-like activity of H2TCPP-NiO NPs originated from the generation of OH radical. Thus it may provide great potential applications in biomedicine, biotechnology and environmental chemistry.