Research Of Detection Method For Profenofos Residues In Vegetables By Electrochemiluminescence Aptasensor Based On N-(4-Aminobutyl)-N-ethylisoluminol

Profenofos is a commonly used organophosphorus pesticide in vegetables with a wide insecticidal range,moderate toxicity,and difficulty to degrade.Therefore,the phenomenon of residue exceeding the limit is frequent,which is harmful to health.Vegetables are in high demand in China and are the main cash crops.Due to their short shelf life,the matrix of samples is extremely complex.The traditional analysis technology for the detection of profenofos residue has high sensitivity and reliability,but it still has some shortcomings such as time-consuming and expensive equipment.Therefore,there is an urgent need to establish highly rapid and simple detection methods.Aptamer（Apt）is a new kind of biometric element,which can recognize the target with high affinity and specificity.In this study,electrochemiluminescence（ECL）aptasensors were developed for the detection of profenofos residues in vegetables such as cabbage,kale,and cauliflower.（1）In order to explore the effect of ECL aptasensor based on N-（4-Aminobutyl）-N-ethylisoluminol（ABEI）for the detection of profenofos residues in vegetables,two kinds of ECL composite nanomaterials were prepared based on ABEI for the construction of relevant ECL aptasensors,respectively.Firstly,ABEI,silver nitrate（Ag NO₃）,and graphene oxide（GO）were used to fabricate composite nanomaterials with simple structure,uniform dispersion,and strong ECL signal;Secondly,in order to pursue further stable amplification of the ECL signal and optimize the structure of the ECL aptasensor.Cuprous oxide（Cu₂O）was prepared.ABEI was coated on the surface of Cu₂O,Ag NO₃ was reduced by ABEI to Nano Silver（Ag NPs）on the surface of Cu₂O,and core-shell nanomaterial could be prepared to achieve synergistic amplification of the ECL signal.The results showed that both materials had a good ECL effect,but the composite material with a core-shell structure could realize cooperative signal amplification and had a better ECL effect.（2）In order to verify whether the aptasensor base on complex ABEI-Ag NPs-GO could detect the residue of profenofos in vegetables,an ECL aptasensor was constructed based on ABEI-Ag NPs-GO as a luminescence material.The surface of Ag NPs in ABEI-Ag NPs-GO was immobilized with a thiol-modified aptamer to capture the profenofos pesticide.The ECL signal of the aptasensor was attenuated in the presence of profenofos.At the same time,cyclic voltammetry was detected in an electrochemical and ECL workstation,which further proved whether the ECL aptasensor was successfully constructed.Through detection and calculation,it was concluded that the Limit Of Detection（LOD）of the aptasensor was 6.7×10^-2 ng/m L,the correlation coefficient（R²）was 0.9991,the detection range was 1×10^-1 ng/m L～1×10⁴ ng/m L and the actual sample spike recovery rate was 98.0%～107.4%.（3）In order to further improve the performance of the ECL aptasensor,Cu₂O,a semiconductor material with a photocatalytic effect,and gold nanoparticles（Ag NPs）were used for synergistic signal amplification.The binary composite nano-material Cu₂O-ABEI-Ag NPs with the core-shell structure were introduced,and an"on-off"ECL aptasensor with switching switch signals was designed by using the molecular probe with thiol-modified aptamers and T-type aptamers of all thymidines(T_Apt)to detect profenofos.Cu₂O had a large specific surface area and could increase the number of Ag NPs immobilized,while an increase in the number of Ag NPs could immobilize more aptamer complements the strand(C_Apt).Simultaneously,Cu₂O and Ag NPs were used for double amplification of the ECL signal.Mercury ions(Hg²⁺)could not only quench the ECL signal of ABEI but also bind to T_Apt,so the preparation of molecular probes with T_Apt and Hg²⁺could lead to ECL signal quenching（signal switching state"off"）.After the addition of the profenofos,C_Apt competed with the target for the Apt,resulting in the recovery of the ECL signal（signal switch state"on"）.Using the structure of the"on-off"switchable switch signal,the"false positive"phenomenon could be avoided.Finally,under optimal conditions,the detection range of aptasensor was 1×10^-3 ng/m L～1×10² ng/m L.The LOD of the aptasensor was 3×10^-4 ng/m L,and the recovery rate was 94.34%～113.80%.In this work,luminescent materials were prepared based on ABEI to construct ECL aptasensors for rapid detection of profenofos residues in vegetables,which provided a valuable reference for the development of rapid detection field.