Colorimetric Sensing Of Pesticide Based On Gold Nanorod Etching

Pesticide pollution is one of the most prominent environmental problems,and its testing has been widely concerned;at the same time,due to the excessive use of pesticides in agriculture and industrial production,the agricultural and industrial products have exceeded the standard,which has led to a series of serious food pollution and human health damage.Many traditional techniques that have been developed have made tremendous contributions to the detection of pesticide residues.However,in recent years,due to the increasing diversity of pesticide monitoring needs,traditional technical methods have gradually failed to meet the immediate,convenient and economical testing needs,therefore,it is extremely urgent to develop more powerful and accurate sensing tools.Among them,the colorimetric sensing technology has been researched more and more extensively,and has demonstrated good detection performance in the fields of sensing and detection of pesticides and various harmful substances.Because the colorimetric sensing strategy has the convenience,economy and immediacy that traditional techniques do not have,it shows its unique advantages in the detection of environment and food pollution.Among the many colorimetric sensing methods,the colorimetric method based on gold nanomaterials has attracted more attention due to its high sensitivity,distinctive optical characteristics and unique color signal conversion strategy.However,the development of colorimetric detection using gold nanomaterial size/shape-dependence remains to be further expanded.Based on this,this paper designs and develops a new method for colorimetric sensing detection of herbicide aminotriazole and organophosphorus pesticides using gold nanomaterials as the color development substrate.(1)The gold nanorod etching mediated by the regulation of catalase activity is used for the detection of the herbicide aminotriazole.Aminotriazole(3-amino-1,2,4-triazole,Aminotriazole,ATZ)is one of the most widely used herbicides and is often used in agricultural production.However,it is carcinogenic and poses a great threat to human health and the natural environment.Therefore,it is urgent to design and develop efficient detection methods for ATZ monitoring.However,because of the difficulty to molecularly recognize it,ATZ is limited to be detected by conventional analysis technologies which are generally complex apparatus-dependent readout.Here,a novel colorimetric assay based on the etching of gold nanorods(Gold NanoRods,AuNRs)is proposed to evaluate ATZ level with the naked eye.This detection relies on the oxidation of I-via H2O2 to produce I2,which can longitudinally etch AuNRs quickly with blue-shift of the longitudinal localized surface plasmon resonance peak and color change.When in the absence of ATZ,active catalase(CAT)decomposes H2O2 into H2O and O2,AuNRs cannot be etched.The presence of ATZ can cause the deactivation of CAT,which affects the amount of H2O2 and subsequent I2,resulting in color change of the system.The multicolor signals can be easily identified by the naked eye.Based on this mechanism,the results show that the method has a good linear relationship between 5-70 μM(R2-0.9821),the minimum detection limit is 1.3 μM,strong anti-interference ability,and has a good water and food sample testing capabilities.(2)Organophosphorus pesticides(OPs)are favored for their high efficiency and wide range of effects,and are often used as agricultural pesticides and herbicides.However,the abuse of organophosphorus pesticides in traditional agricultural practices and modern industries has led to an increase in pesticide residues in air,water,soil,agricultural products,and food.At the same time,OPs residues,if ingested by humans,inhaled or infiltrated through the skin,can cause a series of serious health problems.Therefore,it is important to design and develop real-time quantitative detection methods for OPs.In this work,a colorimetric method based on in situ sulfhydryl compound inhibition of gold nanorod etching was developed for the detection of OPs.Studies have shown that organophosphorus pesticides inhibit acetylcholinesterase activity,causing the latter to lose catalytic activity.In this work,Acetylthiocholine iodide(ATCI)was used as a substrate for acetylcholinesterase,and ATCI was catalytically decomposed into choline and could not undergo redox reaction with potassium iodate(KIO3);When OPs is present,acetylcholinesterase is inhibited,and ATCI can be oxidized by potassium iodate(KIO3)to form iodine(I2),finally,the latter triggers the etching reaction of the gold nanorods,which causes the color change of the gold nanorod solution in the concentration dependence of OPs to gradually change from brown to red.Based on this mechanism,in this paper,triazophos was selected as an organophosphorus pesticide model analyte,the built method achieves good detection performance,it has a good linear relationship in the range of 12-117 nM(R2=0.9908),and the minimum detection limit is 2.02 nM,and it has good water and food sample detection performance.The experimental data proves that the method has good organic phosphorus detection ability and great potential for practical application.