Methods Research Of Nanobiosensors In Acetamiprid Detection In Tea

Tea,as one of the most popular beverages in the world,is not only our country's important agricultural crop,but also a commonly exported commodity.However,for prevention and controlling of insect in tea,pestcides are widely used,especially acetamiprid,a represent of new and efficient ones.Acetamiprid works efficently,but the residues are worrying.The existing detection methods either have limited and time-consuming applcations,or have complex preprocessing steps and need expensive instruments,which are not suitable for rapid and real-time detection.Apatmers have the merits of low-costing and high specificity;and nanomaterials are sensitive to reactions and have reliable results.Therefore,we attempt to combine these techniques with the existing methods,listing acetamiprid as an example,in order to realize rapid and sensitive detection of pestcides in tea.The details are as follows:1.Detection of acetamiprid in tea based on upconversion fluorescence nanobiosensor.Herein,the nanobiosensor consists of UCNPs and GNPs,where UCNPs function as energy donors and GNPs as acceptors.GNPs quench the fluorescence of UCNPs via FRET;and acetamiprid specifically interacts with aptamer,causing the conformation changes of aptamer from random coil to hairpin structure.Accordingly,aptamer no longer stabilizes the GNPs in salt solution,leading to the varying aggregation extent of GNPs.Under the optimized conditions,the enhancement efficiency was observed to increase linearly with the concentration of acetamiprid from 50 nM to 1000 nM,resulting in a relatively low limit of 3.2 nM.Furthermore,the ability of the aptamer-nanosensor to detect acetamiprid was also confirmed in adulterated tea samples.This nanobiosensor uses 980 nm as the exciting laser,which can overconme the background autofluorescence;and has a promising application in pesticides determinations in tea.2.Detection of acetamiprid in tea based on surface-enhanced Raman scattering nanobiosensor.Herein,aptamers can stable GNPs in salty solution;and crystal violet can report signal.Acetamiprid could specific recognize aptamer,which result in the conformation changes of aptamers to hairpin structure from random coil.Thus,the dispersed GNPs aggregated in salty solution;and the plasmonic coupling induced SERS of varying gold aggregations can be distinctly reflected by GNPs surface attached Raman report molecule(crystal violet here)in enhanced Raman spectroscopy.Under an optimized condition,the SERS intensity can be observed increase linearly under a wide acetamiprid concentration range from 30 nM to 4000 nM,with a relatively low limit of 17.6 nM.Furthermore,the ability of the aptamer-nanosensor to detect acetamiprid was also confirmed in adulterated tea samples.Thus,with Raman as thedetection machine,the sensor is expected to be used as a candidate method for rapid detection of pesticide residues in tea.3.Detection of acetamiprid in tea based on gold nanoparticles colorimetric nanobiosensor.Herein,aptamers was the recognition element and cysteamine-stabilized gold nanoparticles(CS-AuNPs)were the color indicator.The electrostatic attraction between the CS-AuNPs and aptamers can induce the aggregation of CS-AuNPs,and this causes a rapid red-to-blue color change.Acetamiprid could specifically bind to the aptamers to form an aptamers-acetamiprid complex,inducing the conformation change of aptamers.As a result,CS-GNPs were no longer aggregated;and the Abs value recovered.Under an optimized condition,the Abs intensity can be observed increase linearly under a wide acetamiprid concentration range from 10 nM to 40 nM,with a relatively low limit of 0.72 nM.Furthermore,the ability of the aptamer-nanosensor to detect acetamiprid was also confirmed in adulterated tea samples.Therefore,the ultrasensitive detection of the sensor can provide references for the determination of pesticide residues in tea.