Development Of Methods For Colorimetric Detection Of Small Chemical Hazards Based On Peroxidase Activity Of Nanomaterials

With the rapid development of economy and the rise of living standards,people are increasingly demanding food and environmental safety,especially the problem of hazardous small molecule chemical exceeding the standard.Although the conventional detection methods for environmental and food safety have been widely used,most of them are difficult to meet the practical needs of real-time monitoring,which ascribe to the fact that such methods needs expensive testing costs,complex sample preparation,professional operators and precision instruments.Therefore,developing a simple,fast,low-cost and ultra-sensitive detection method in the field of food and environmental safety.At present,with the rapid development of biotechnology and nanotechnology,the new detection method has been established using the catalytic activity of nanomaterials as an output signal.Such method has the advantages of low cost,simple and excellent stability,which has attracted the more attention of researchers.In this paper,the detection of hazardous small molecule chemical in the food and environment is studied.The main research contents are as follows:?1?A detection method of dimethoate pesticide based on inhibition of the peroxidase activity of gold nanoparticles?Au NPs?was established.Three kinds of Au NPs with different surface charges prepared by reduction method,and them were used respectively to established the chemosensor of dimethoate detection.Finally,the citrate modified Au NPs?cc-Au NPs?was selected to construct the chemosensor.In the absence of target,Au NPs can oxidize o-phenylenediamine?OPD?to form product,which has a characteristic absorption peak at 450 nm and displays yellow.In the presence of dimethoate,the metal ions on the surface of the Au NPs are chelated by the target,which will weaken the peroxidase activity of the Au NPs and led to the appearance of light yellow or even colorless solutions.The variation of color is relevant to the concentration of dimethoate,which can be quantitative determined.Under the optimal catalytic conditions,the proposed chemosensor can detect dimethoate in a linear range from 10?g/L to 400?g/L,with a limit of detection?LOD?as low as 4.7?g/L and exhibits excellent selectivity against other competitive pesticides.Moreover,the recovery rate of dimethoate was 89.4%-95.8%in the actual samples,and gas chromatography was subsequently used to further verify the reliability of such method.?2?A colorimetric method for the detection of glyphosate pesticides based on the inhibition of the catalytic activity of porous Co₃O₄ peroxidase was constructed.In the sensing system,porous Co₃O₄ can catalyze the H₂O₂ to generate hydroxyl radicals?·OH?,which cause the substrate 3,3',5,5'-tetramethylbenzidine?TMB?lose one electron,making sensing solution exhibits blue solutions.Glyphosate can interact with porous Co₃O_4,resulting in the decreasing of·OH,which will weaken the oxidation of TMB.At this time,the sensing solution appears light blue or colorless,and the degree of color change is positively correlated with the concentration of glyphosate.Under optimal conditions,the method can detect glyphosate in a linear range from 5?g/L to80?g/L,with a limit of detection?LOD?as low as 2.37?g/L,and exhibits excellent selectivity against other competitive pesticides.Furthermore,the recovery rate of glyphosate detection was 86.4%-95.2%in the actual samples.?3?A method for colorimetric detection of acetone rely on the inhibition of WS₂nanosheet peroxidase activity was established.In the presence of H₂O₂,WS₂ nanosheets can catalyze the oxidation of OPD,making the color of the sensing solution displays yellow.When acetone is added,the WS₂ nanosheet peroxidase activity was inhibited,leading to the change of the sensing solution from yellow to colorless,and the change of color is relevant to the concentration of acetone,which can be determined by naked eyes.Under the optimal condition,the method can detect acetone in a linear range from5 mg/L to 125 mg/L,with a limit of detection?LOD?as low as 3.08 mg/L,and exhibits excellent selectivity against others competitive chemical.Furthermore,the recovery rate of acetone detection was 85.8%-107.5%in water samples.In conclusion,this paper relies on the peroxidase activity of nanomaterials and its change in catalytic activity,constructed three detection methods for the detection of hazardous small molecule chemical.The methods developed in this paper is simple,fast,reliable,low cost,and does not need any complex equipment,which will facilitate the detection of hazardous small molecule chemical in food and environment.