Synthesis of Au-Pt bimetallic nanozymes with dual-enzyme activity and its application in organophosphorus pesticides detection
Objective To synthesize a Au-Pt bimetallic nanozymes(Au-PtNFs)with oxidase and peroxidase dual-enzyme activity,and apply them in detection of organophosphorus pesticide.Methods The 3 kinds of Au-PtNFs were prepared through seed-mediated method by adjusting the amount of chloroplatinic acid,and their enzyme activities were determined using 3,3',5,5'-tetramethylbenzidine(TMB)as the substrate.The nanozyme exhibiting the highest enzyme activity was selected and combined with the catalytic effect of acetylcholinesterase to establish a detection method for organophosphorus pesticide.Results The 3 kinds of prepared nanozymes all had flower-like structures,and the particle size enhanced with the increasement of chloroplatinic acid concentration.Steady-state dynamic experiments showed that all bimetallic nanozymes had dual-enzyme activity,and the best enzyme activity was obtained when the concentration of chloroplatinic acid was 5 mmol/L.Absorption at 620 nm exhibited a good linear correlation with the logarithm of chlorpyrifos concentration in the range of 40-90 nmol/L,and the limit of detection was 1.00 nmol/L.The method demonstrated excellent specificity and anti-interference ability,and achieved great recovery rate in real samples.Color value analysis software was used for the detection of chlorpyrifos based on smartphone.The linear range was 30-100 nmol/L and the limit of detection was 1.06 nmol/L.Conclusion The prepared Au-PtNFs exhibiting dual-enzyme activity are effectively utilized for detection of organophosphorus pesticides,which offers a novel perspective for visual detection of organophosphorus pesticides in fruits and vegetables.
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