Study On Preparation And Application Of Time-Resolved Fluorescence Probe Based On Eu

Chemical pollutants such as mycotoxins,pesticides and veterinary drugs in food and the environment seriously threaten human health.At present,the detection methods for organic pollutants mainly rely on large-scale instruments such as chromatography and mass spectrometry.However,as the number of test samples continues to increase,the requirements for detection timeliness continue to be strict.Those traditional methods that are time-consuming,cumbersome,and costly cannot meet increasingly stringent testing requirements.Therefore,the developed detection method should be simple,instant and accurate to cope with the complex detection requirements in food and the environment.The characteristics of long fluorescence lifetime,narrow emission bandwidth,and large Stokes shift of rare earth metals make it a promising time-resolved fluorescent material,and avoiding the interference of background fluorescence,and providing a guarantee for improving the accuracy of the detection method.Immunoassay is easy to operate and time-consuming to provide the possibility of instant detection.At present,there are still shortcomings in the systematic research of Time-resolved fluorescence energy transfer(TR-FRET)and lateral flow immunoassay(LFIA)based on the rare earth fluorescent materials in China.Therefore,in this study,four Eu-based time-resolved fluorescent probes were prepared by organic,inorganic,and polymer methods for TR-FRET and LFIA,and four rapid detection platforms were systematically created.To detect antibiotics and mycotoxins in the environment and food.The main work and research innovations are as follows:1.Eu-PCY is obtained through organic synthesis.The nitrogen in bipyridine provide the coordination conditions for Eu³⁺.The appropriate cavity size makes Eu³⁺perfectly wrapped in the organic framework to prevent H₂O molecules to quenching fluorescence.The quantum yield of Eu-PCY is as high as 11.2%,and the fluorescence lifetime can reach 1244?s.Establish a highly sensitive and free-wash TR-FRET method for the detection of tetracycline in environmental samples.Under optimal parameter conditions,LOD(IC₁₀)and IC₅₀ were determined to be 0.0106 ng/mL and 0.4188 ng/mL,respectively.The results show that the method has good sensitivity and reliability.Compared with the traditional ELISA,this method has less background interference,only one step is required,free wash procedure is required,and the detection result can be obtained through 30 min incubation,which improves the detection efficiency.2.When dealing with environmental issues,monitoring pollutants is to effectively eliminate the hazards of pollutants.Therefore,detection and removal of contaminants are equally important.The third chapter of this thesis is to synthesize a new dual-functional Eu/Zr-MOF probe,which has unique emission characteristics of Eu³⁺and high adsorption performance of Zr-MOF,which can realize simultaneous sensing and adsorption of tetracycline(TC).Eu/Zr-MOF can be easily synthesized by traditional hydrothermal method.In an aqueous solution,Eu³⁺will preferentially coordinate with TC molecules,and TC will act as an antenna to enhance the characteristic fluorescence of Eu³⁺.However,TC can be sensed in a wide dynamic range(1.00-500 ng/mL)and low detection limit(0.92 ng/mL).In addition,the adsorption capacity of Eu/Zr-MOF for TC is as high as 289 mg/g.The idea of dual-functional materials proposed in this work can provide a reference for the monitoring and removal of more pollutants.3.Both TR-FRET and Eu/Zr-MOF can achieve rapid detection.However,it is LFIA that can better meet the requirements of POCT in practical applications at this stage.LFIA uses the principle of chromatography to separate test samples.The qualitative or quantitative identification is achieved through the specific recognition of the immune protein by the labeled chromogenic or fluorescent probe.In LFIA,high stability,strong fluorescence,easy labeling and low interference of fluorescent probes have always been the pursuit goals.Therefore,the fourth chapter of this thesis is to synthesize Eu-MOF according to the characteristics and requirements of LFIA.It is a spherical particle with a diameter between 250-400nm.Eu-MOF overcomes the shortcomings of using complex cross-linking agents,and can cross-link antibody proteins with only contact,which simplifies the detection procedure.A TR-LFIA method for detecting aflatoxin B1(AFB1)in corn was established based on Eu-MOF.Through optimization of conditions,LOD is 0.149 ng/mL,which meets the requirements of the national standard and can be used for the rapid detection of AFB1 in corn.4.In practical applications,the complex matrix is the key interference factor that affects the detection effect.Therefore,the fifth chapter of this thesis synthesizes Eu latex microspheres(Eu-CPS)with carboxylated surface.Due to the encapsulation of high molecular polymer,Eu-CPS has high chemical stability and the fluorescence lifetime reaches 534?s.Based on this probe,a TR-LFIA method for the detection of zearalenone(ZEN)was established.Four real samples(wheat,corn,rice,feed)samples were detected through the addition and recovery experiment.The LOD reaches 0.052ng/mL in mixed matrix.The recovery rate of standard addition is between 79.2-106.5%,and the RSD is 6.7-11.5%.The experimental results show that this detection platform has sufficient accuracy and stability to detect ZEN in grain or feed.