Perovskite LaCoO3 nanoparticles as enzyme mimetics: their catalytic properties, mechanism and application in dopamine biosensing

Perovskite LaCoO3 materials (LCO NPs) were prepared and found to possess both peroxidase-like and catalase-like catalytic activities. The LCO NPs can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 generating a blue color change under acidic conditions or decompose H2O2 under alkaline conditions with the generation of oxygen. Catalytic kinetics together with the possible mechanism of the peroxidase-like activity was investigated. The peroxidase-like catalytic properties of LaCoO3 nanoparticles were found to originate from their ability of accelerating electron transfer. Then based on their peroxidase properties, LCO NPs were applied to determine dopamine by using the colorimetric method with the dopamine-dependent successive inhibition reaction. The linear range of dopamine sensing was found to be 0.5-20 mu M and the detection limit (LOD) was also discussed. The standard addition experiments were further performed with recoveries between 95.4% and 103.6%, and all the relative standard deviations (RSDs) were below 4.0%. The determination of dopamine therefore showed high accuracy and efficiency and has potential for the diagnosis of dopamine-related diseases.