| Pesticide residues not only pollute the environment,but also harm human health.Enhancing the detection technology of pesticide residues is of great significance for improving the status of pesticide pollution and monitoring the quality and safety of agricultural products.The traditional technical means used for the detection of pesticide residues are time-consuming and laborious,and the instruments and equipment are expensive.In recent years,biosensor technology has attracted much attention in the field of detection because of its sensitivity and rapidity.The development of nanomaterials is conducive to further improving the sensitivity and accuracy of the biosensor detection system.Therefore,based on the fluorescence signal conversion of gold nanomaterials and the principle of enzyme inhibition,a fast,sensitive and low-cost biosensor system was constructed for the detection of organophosphorus pesticide residues in food.The specific research contents of this paper are as follows:1.Based on the quenching effect of gold nanoparticles(AuNPs)on sodium fluorescein(NaFL),combined with the inhibition effect of omethoate on trypsin(TRY),the fluorescence sensing system of gold nanoparticles/sodium fluorescein/trypsin/protamine(AuNPs/NaFL/TRY/PRO)was successfully constructed for the detection of omethoate.AuNPs were dispersed with negative charge in solution,and the NaFL fluorescence could be quenched by inner filter effect.After the introduction of PRO into the system,the PRO with positive charge could induce AuNPs to agglomerate,and the optical properties of AuNPs in agglomerate state were changed,which greatly weakened the quenching effect of NaFL fluorescence.The fluorescence of the system was enhanced;TRY could hydrolyze PRO specifically,which enhanced the inner filter effect of AuNPs and quenched the fluorescence of the system again.Omethoate could effectively inhibit TRY activity and block PRO hydrolysis,thus causing fluorescence recovery of the system.By detecting the change of fluorescence signal in the system,the rapid,sensitive and low-cost detection of omethoate was finally realized.The experimental results showed that the sensing system had a good linear relationship in the range of 0.002-20 ng/mL,and the detection limit was 0.022 ng/mL under optimal experimental conditions.What’s more,the system had good selectivity and anti-interference ability,which can be used for the analysis of pesticide residues in tap water and baby vegetables,and the recovery rate of spiking was between 89.84%and 119.34%.The relative standard deviation was between 3.24%and 6.03%.Compared with the traditional detection methods,the sensor system had a lower detection limit and a wider detection range,which provided a new method for the specific detection of omethoate.2.Based on the inner filter effect of manganese dioxide nanosheets(MnO2 NSs)on glutathione-protected gold clusters(GS-AuNCs),combined with the inhibition effect of parathion-methyl(PM)on alkaline phosphatase(ALP),a fluorescence sensing system of manganese dioxide nanosheets/glutathione coated gold cluster/alkaline phosphatase/L-ascorbate-2-trisodium phosphate(MnO2 NSs/GS-AuNCs/ALP/AAP)was constructed for the detection of PM.ALP catalyzed the substrate AAP to produce ascorbic acid(AA),which decomposed MnO2 NSs into Mn2+.At this time,GS-AuNCs were added to the system,and it still maintained the original fluorescence.When PM was introduced into the system,the ALP could not catalyze the substrate to produce AA due to its inactivation,the undissolved MnO2 NSs would quench the fluorescence of GS-AuNCs.Thus,the detection of organophosphorus pesticides could be realized by the change of fluorescence signal in the system.The experimental results showed that the sensor had a good linear relationship in the range of 2.5-40.0 μg/mL with the detection limit was 10.62 ng/mL under optimal experimental conditions.Respectively,the sensor had good selectivity and anti-interference ability.It could be used for the detection and analysis of PM in tap water and rice.The recovery rate of spiking was between 90.19%and 100.69%,and the relative standard deviation was between 3.82%and 4.44%.This method provided a new theoretical basis and technical support for the detection of PM. |
