CdTe Quantum Dots And Gold Nanoparticles For Turn-on Fluorescence Detection Of Pesticides

Pesticides effectively solve the problems of crop diseases and insect pests withhigh performance of killing pests. Despite their merits, pesticides are considered tobecome of the most dangerous environmental contaminants because of their ability toaccumulate and their long-term effects on living organisms. Detection for Pesticidesin food became a key technology of food safety testing. Au nanoparticles(AuNPs) andCdTe quantum dots(QDs), as a typical representative of the noble nanoparticles,which possess many unique properties. Because of the good optical properties, AuNPsand CdTe QDs have been widely applied in the fields of environment, medicine andbiology, which have been widely concerned by researchers. In this article, two simple,sensitive and rapid nano-sensor methods based on Inner Filter Effect(IFE) andFluorescence Resonance Energy Transfer(FRET) of AuNPs and CdTe QDs fordetection of pesticides in fruits and vegetables were developed with the specialproperties of nanoparticles.1、A sensitive, selective fluorometric assay was developed to detect glyphosatebased on the FRET between negatively charged CdTe quantum dots capped withthioglycolic acid (TGA-CdTe-QDs) and positively charged gold nanoparticlesstabilized with cysteamine (CS-AuNPs). Oppositely charged QDs and AuNPs canform FRET donor–acceptor assemblies due to electrostatic interactions, whicheffectively quench the fluorescence intensity of CdTe-QDs. The presence ofglyphosate could induce the aggregation of CS-AuNPs through electrostaticinteractions, resulting in the fluorescence recovery of the quenched QDs. This methodis easy to operate with remarkably high sensitivity. Under the optimum conditions, theresponse is linearly proportional to the concentra-tion of glyphosate in the range of0.02–2.0μg/kg, and the detection limit is found to be9.8ng/kg. The proposed methodis a promising approach for rapid screening of glyphosate in real samples, providing asimple method for the analysis of glyphosate.2、A novel label-free aptamer-based fluorescent detection method was developedto detect acetamiprid based on the specific binding of aptamers with acetamiprid, andthe IFE of AuNPs on the fluorescence of CdTe QDs. When CdTe QDs was mixed withAuNPs, the fluorescence of CdTe QDs was significantly quenched via IFE.Acetamiprid-binding aptamer (ABA) could adsorb on the negatively charged AuNPsthrough the coordination interaction to protect AuNPs from salt-induced aggregation.However, the specific binding of ABA with acetamiprid could release the ABA fromthe surfaces of AuNPs and decrease the salt tolerance of AuNPs, so the IFE-decreased fluorescence of CdTe QDs was regained with the presence of acetamiprid. Under theoptimum conditions, the fluorescence response is linearly proportional to theconcentration of acetamiprid in the range of1.2–21.6μg/kg, and the detection limit isfound to be as low as0.192μg/kg. The proposed method displays remarkableadvantages of high sensitivity, rapid analysis, excellent selectivity, and would besuitable for the practical application of target screening in real samples.