| Pesticide is one of the most important environmental pollutants,which seriously affects the ecological environment and threatens human health.At present,the commonly used analysis and detection methods mainly include gas chromatography,high performance liquid chromatography,capillary electrophoresis,gas chromatography-mass spectrometry,liquid chromatography-mass spectrometry,etc.However,these detection steps are redundant,time-consuming,and require expensive large instruments,which are not suitable for low-cost and rapid detection and analysis.Therefore,how to realize the rapid and highly sensitive detection of trace pesticide residues has become an urgent problem to be solved.Cucurbit[n]urils is a kind of macrocyclic host compound with neutral hydrophobic cavity,electronegative port and positive outersurface.It can interact with dye molecules to form a probe with optical response.According to the difference of affinity cucurbit[n]uril/dye probe for multicomponent pesticides,cucurbit[n]uril-based supramolecular sensing array system is designed and constructed to study the recognition and response performance of cucurbit[n]uril-based supramolecular sensing array system for multicomponent pesticides.This provides an experimental basis for the detection of pesticide residues with complex components.The main achievements are as follows:1)The modes of action between Th T and Q[8]were studied,and it was found that there were two modes of action between Th T and Q[8]with stoichiometric ratios of2:1 and 2:2.Supramolecular compounds Th T@Q[8]（stoichiometric ratio 2:2）were selected as probes to systematically study the response behavior of Th T@Q[8]probe to aromatic pesticides（FBZ,CBZ,TBZ,TDZ,TCZ）.The results showed that the presence of five pesticides made the fluorescence of the system blue shift and enhanced in different degrees,and the fluorescence intensity showed a good linear correlation with the concentration of pesticides,and the detection limit was as low as10-7 M.The results of 1H NMR showed that Th T and pesticides formed electron transfer complex in the cavity of Q[8].Due to the different structure of pesticides,the probes had different fluorescence responses to the above five pesticides.According to the fluorescence color response of probe Th T@Q[8]to pesticide under 365 nm UV lamp,a supramolecular colorimetric sensor array was designed and constructed based on RGB three-channel.By extracting the RGB change value of fluorescence color after the probe responded to pesticides and combining principal component analysis（PCA）and linear discriminant analysis（LDA）,the qualitative and quantitative identification ability of the array for pesticides was investigated,and the recognition and differentiation of five quaternary ammonium pesticides was realized.The sensitivity of Th T@Q[8]colorimetric array to pesticide identification was tested,and the results showed that the colorimetric array realized the identification and differentiation of pesticides with different concentrations.There was a good linear correlation between Euclide distance（ED）and pesticide concentration,and the detection limit was as low as 10-6-10-7 M.The identification ability of Th T@Q[8]colorimetric array to binary and ternary pesticide mixtures was tested,and it was found that Th T@Q[8]array classified binary and ternary pesticide mixtures well.At the same time,the applicability of Th T@Q[8]colorimetric array in actual samples was explored,and the results showed that the array not only well identified five quaternary ammonium pesticides in tap water,but also classified five quaternary ammonium pesticides in Huaxi river water.In addition,we also investigated the rapid detection of pesticides by probe Th T@Q[8]on the strip and found that probe Th T@Q[8]could identify pesticides on the strip.Finally,the detection of pesticide residues in living cells by the probe Th T@Q[8]was realized.This work provides experimental basis for rapid analysis and detection of multi-component pesticide residues.2)The interaction modes of C30 and C7 with Q[8]were investigated.Both C30and C7 interact with Q[8]in stoichiometric ratio of 2:3,where 2C30@3Q[8]（P1）emits yellow fluorescence,while 2C7@3Q[8]（P2）emits orange fluorescence,and their fluorescence colors are quite different.The identification responses of probes P1and P2 to quaternary ammonium pesticides（PQ,DQ,DFQ,MC and CC）were investigated.The results showed that probes P1 and P2 had different fluorescence responses to different pesticides.P1 and P2 were used as components to construct the supramolecial fluorescence sensing array,and the identification and discrimination ability of the array to quaternary ammonium pesticides was investigated.The array not only qualitatively classified five quaternary ammonium pesticides 100%correctly,but also quantitatively classified DFQ with different concentrations correctly.At the same time,the identification ability of the array to the mixed pesticide was investigated,and the result was that the concentration of DFQ-DQ binary mixed pesticide was correctly recognized and distinguished.In addition,the identification and discrimination ability of the array in real samples（tap water and Huaxi river water）was also explored,and it was found that the array could classify five quaternary ammonium pesticides in tap water and Huaxi river water well.It is expected to provide a new way for rapid,accurate and low-cost screening of quaternary ammonium pesticides.3)The photoluminescence properties of cucurbit[n]uril in solid and solution state were studied systematically.The results showed that the cucurbit[n]uril in solid state can emit bright blue fluorescence under excitation of 365nm uv light,which has excitation wavelength dependence.When the concentration of cucurbit[n]uril solution reaches a certain level,it will emit fluorescence,and the fluorescence intensity increases with the increase of cucurbit[n]uril concentration,which has the characteristics of cluster-induced luminescence.By analyzing the single crystal of cucurbit[n]uril,we believe that the outersurface interaction induced by cucurbit[n]uril itself may be the main factor leading to melon ring luminescence.In addition,the effects of aromatic compounds and anions on the photoluminescence of cucurbit[n]uril were investigated,and it was found that aromatic compounds and anions would weaken the fluorescence properties of cucurbit[n]uril.Then,the application of cucurbit[n]uril fluorescence in detection was preliminarily studied based on the effect of ions on cucurbit[n]uril fluorescence,and the result was that Q[7]（0.01 M）specifically recognized Fe3+,which was limited to 1.14×10-6 M..Finally,the application of cucurbit[n]uril in biological cells and gel was preliminatively explored,and it was found that Q[7]（0.1 M）could stain PC3 cells,and the stained cells emitted a wide range of fluorescence,such as blue,green and yellow,and the fluorescence of Q[7]in gel state was much stronger than that in liquid state.The clustering luminescence characteristics of cucurbit[n]uril may have potential applications in analytical sensing and biological imaging. |
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