Spectrometric Methods For The Determination Of Acetamiprid Based On Aptamer And AuNps

As a novel chlorinated nicotinoid pesticide,Acetamiprid primarily targets nicotinic acetylcholine receptors in the nervous system of insects and can effectively control pests.Studies that residues in the environment caused by the widespread use of acetamiprid are significant negative effects on mammals and other non-target organisms have been shown.Therefore,it is of great significance to develop a rapid method for the detection of acetamiprid residues in actual water.In this study,a detection method combined with ultraviolet and fluorescence spectra for acetamiprid residues was established based on acetamiprid specific aptamers and gold nanoparticles(Au NPs).By truncating the original aptamers,aptamer sequences with higher detection sensitivity and lower cost were re-screened.Firstly,a combined UV-visible with fluorescence detection method for acetamiprid was established based on the “aggregation and dispersion” of Au NPs.In this method,the selected acetamiprid specific aptamer as target recognition probe and Au NPs and Rhodamine B as signal indicators.In the absence of acetamiprid,Au NPs were "protected" by aptamers and distributed uniformly at higher Na Cl concentrations,with an absorption peak at 520 nm in the UV-vis spectrum and a good quenching ability to Rhodamine B fluorescence.In the presence of acetamiprid,a small amount of Au NPs lost its protective effect and aggregated,while the absorption peak of UV-vis spectrum redshifted from 520 nm to 680 nm.In addition,the quenching effect of Au NPs on Rhodamine B fluorescence was weakened when the aggregation occurred.Therefore,it is possible to accurately detect acetamiprid in the system by UV-vis method or fluorescence method.The detection limit of the combined method was 0.0559 μM and the linear relationship was good in the range of 0.1-60μM.This method had been applied to the detection of actual water samples,and the results were comparable to those obtained by standard method using high-performance liquid chromatography(HPLC).This combined sensing model had a lower detection limit and a wider linear quantitation range than a single UV-vis or fluorescence route,and had great potential for application in the detection of acetamiprid residues in actual environmental samples.In order to improve the affinity and detection sensitivity between aptamers and acetamiprid,and to reduce the development cost,the performance of the aptamer-based acetamiprid detection method was improved from the point of view of the aptamer.The original aptamer was truncated,and four different aptamer sequences were obtained by truncation in different sequence regions according to the secondary structure of the computer simulated aptamer.And the interaction between the aptamer and acetamiprid was simulated by molecular docking,which proved that all four sequences could be combined with acetamiprid(Apt-J1,Apt-J2,Apt-J3,Apt-J4).However,the subsequent experimental research proved that the affinity and specificity of Apt-J1 and Apt-J3 were poor,Apt-J2 and Apt-J4 had strong affinity and specificity.At the same time,compared with the original aptamer UV-vis detection method,the sensitivity of quantitative detection was improved by about 7.5 times and 15 times,respectively.In addition,the two truncated aptamers could be used to realize the experimental path of Au NPs prebinding with aptamers and then adding the solution to be tested for detection.The linear ranges of Apt-J2 and Apt-J4 for optimized UV-Vis detection were 1-70 μM,0.5-40μM.Therefore,Apt-J2 and Apt-J4,as two newly obtained short chain aptamers can be used as better candidate aptamers for the detection of acetamiprid using aptamers in the future.