| Organophosphorus pesticide is the most widely used pesticide in China and plays an extremely important role in agricultural production.However,excessive or unreasonable use will result in pesticide residue,which has a serious impact on the environment and food safety.The present rapid detection methods of pesticide residue have some problems such as low detection sensitivity,false positive,false negative and so on.To establish a rapid and accurate detection method of pesticide residue,electrochemical sensing technique combined with aptamer synthesis whose advantages are artificial synthesis and high specificity was employed,with the commonly used organophosphorus pesticides chlorpyrifos and profenofos as test objects,an electrochemical aptasensor for the detection of organophosphorus pesticide residue in vegetables was constructed.The paper explored the feasibility of this method for the detection of organophosphorus pesticide residue,which provided a theoretical basis for the rapid detection of pesticide residue.The main contents and conclusions of this paper are as follows:1.Electrochemical aptasensor based on ordered mesoporous carbon/ferrocene@ multi-walled carbon nanotubesIn order to explore the feasibility of an electrochemical aptasensor to detect the organophosphorus pesticide residue,aptamer was used as a biological recognition element in the experiment,using chitosan functionalized mesoporous carbon with porosity,large specific surface area,good dispersion and employing ferrocene@multi-walled carbon nanotube with good electrical conductivity and biocompatibility,and then an electrochemical aptasensor based on nano signal amplification technique was developed to quantitatively detect organophosphorus pesticide residue.The detection limit of chlorpyrifos was 0.33 ng/m L and the recoveries of leeks,lettuce and cabbage were 98.5%-107.2%.2.Electrochemical aptasensor based on carbon black/graphene oxide@Fe3O4In order to have a further exploration of the effect of nanomaterials signal amplification technique on electrochemical aptasensor technology,a new type of nano materials electrochemical aptasensor was prepared based on the ideal dispersion and electrochemical activity of carbon black,and the characteristics of increasing current and specific area synergistically of graphene oxide@Fe3O4 nanocomposites.The detection limit was 0.033 ng/mL for chlorpyrifos,and the recoveries of leeks,lettuce and cabbage were 96%-106%.3.Electrochemical aptasensor based on Vent polymerase and T7 exonuclease auxiliary double cycle signal amplification strategyIn the research,a homogeneous electrochemical aptasensor was designed based on the combination of the dual recycling amplification technique and the positive signal sensing strategy.With the target triggering hairpin chain open,primers and Vent polymerase can be high fidelity to generate the partially complementary DNA duplexes and release the target;T7 exonuclease can specifically digest double stranded nucleotides,dissociate the complementary strand from it and cause the end-labeled ferrocene closed to the electrode surface and generate a current signal.The released target and the dissociated complementary strands were separately recycled,thereby increasing the response signal.In this experiment,profenofos was employed as a model analyte and the detection limit was 0.01 ng/mL,and the recoveries of leeks,lettuce and cabbage were 98.0%-104.3%.This paper verified the feasibility of electrochemical aptasensors for detection of organophosphorus pesticide residue.On this basis,a variety of electrochemical aptasensors were further established using nanomaterials and target cycle signal amplification technology.It was concluded that the electrochemical aptasensors based on double cycle signal amplification strategy not only can eliminate the complex steps of the preparation of nanometer materials and electrode assembly process,but also have higher sensitivity,providing a new method for rapid detection of organophosphorus pesticide residue. |
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