Construction Of Bismuth Perovskite Quantum Dot Fluorescence Sensor For The Detection Of Oxytetracycline

Oxytetracycline（OTC）,as a representative tetracycline antibiotic,has been used more and more in medicine and animal husbandry.However,sewage treatment and biological metabolism have poor degradation effect on OTC.A large amount of OTC will be discharged into the environment in its original form,posing a serious threat to the ecological environment and biological health.Existing OTC detection methods such as chromatography have non-negligible shortcomings such as high cost and complex operation,which limit their wide application.Quantum dot-based fluorescence analysis has the advantages of easy to operate,low cost,good sensitivity and stability,which is an effective way to achieve efficient detection of OTC.In recent years,perovskite quantum dots（PQDs）have attracted widespread attention due to their excellent optical properties such as low-cost preparation process,high fluorescence quantum yield,and tunable emission wavelength.However,the instability and toxicity of perovskite quantum dots are the main obstacles limiting their application.Therefore,it is necessary to develop simple,repeatable strategies to improve the stability of perovskite quantum dots,reduce their toxicity,and maintain excellent optical performance.In this paper,a highly stable and non-toxic bismuth perovskite quantum dot material was prepared by different preparation methods and surface modification techniques,and on this basis,its boric acid functionalization and molecular imprinting technology were used to study the detection behavior of trace OTC in actual samples.The main research contents of this paper are as follows:1.In order to realize the preparation of highly stable and non-toxic perovskite quantum dots,bismuth perovskite quantum dots Cs₃Bi₂Br₉ PQDs fluorescence sensor was prepared by ligand-assisted reprecipitation using oleamine（OAm）and oleic acid（OA）as ligands,which can be stably distributed in the ethanol phase and have fluorescence quenching of OTC.The TEM,FT-IR test results proved the successful synthesis of Cs₃Bi₂Br₉ PQDs,and the fluorescence test results showed that Cs₃Bi₂Br₉ PQDs had high sensitivity to OTC.By studying the influence of p H environment,detection concentration and response time on the detection system,the optimal detection conditions were determined,and the detection ability of Cs₃Bi₂Br₉ PQDs on OTC was verified by fluorescence detection experiments,and a linear relationship was established.Finally,through the spike recovery experiment of soil samples,the quantitative detection of Cs₃Bi₂Br₉ PQDs on environmental OTC was successfully realized.2.In order to improve the optical performance of the sensor and the detection performance of OTC,3-aminophenylboronic acid（APBA）was used to surface modify Cs₃Bi₂Br₉ to synthesize boric acid functionalized bismuth perovskite quantum dots Cs₃Bi₂Br₉-APBA.The amount and time of APBA modification were optimized,and the optical and detection performance of Cs₃Bi₂Br₉ before and after APBA modification was compared,and the results showed that Cs₃Bi₂Br₉-APBA had better optical performance and a higher degree of quenching of OTC.The fluorescence pattern and stability under different solvents were analyzed,and the influence of detection concentration,detection time and other conditions on the fluorescence sensor was studied,and the optimal detection conditions were obtained.Under optimal detection conditions,the Cs₃Bi₂Br₉-APBA fluorescence intensity had a linear relationship with the 0.1～18μM OTC concentration range,and the detection limit was 0.0802μM.Finally,the mechanism of Cs₃Bi₂Br₉-APBA in detecting OTC by ultraviolet characterization and fluorescence lifetime analysis was inferred as internal filtration effect（IFE）,and the successful application in actual samples also indicated that Cs₃Bi₂Br₉-APBA has broad application prospects in the field of fluorescence sensing detection.3.In order to further improve the anti-interference ability of the sensor to OTC and realize the selective identification of OTC,a silicon-based bismuth perovskite molecularly imprinted fluorescence sensor（Cs₃Bi₂Br₉@Si O₂-MIPs）was prepared by reversed-phase microemulsion blot with Cs₃Bi₂Br₉-APBA as the fluorophore,tetraethyl silicate（TEOS）as the crosslinker,and OTC as the template molecule.The fluorescence detection results showed that the Cs₃Bi₂Br₉@Si O₂-MIPs had high selectivity for the detection of OTC.In the range of 0.8～130μM OTC concentration,a good linear relationship between OTC concentration and Cs₃Bi₂Br₉@Si O₂-MIPs fluorescence intensity was established,R² was 0.9975,the detection limit was 0.32μM,and the imprinting factor（IF）was 1.254.The successful application of Cs₃Bi₂Br₉@Si O₂-MIPs to the determination of OTC in actual samples showed a spiked recovery rate of 93.33%～103.9%and a relative standard deviation（RSD）of 3.7%～7.9%,indicating the application potential of the sensor to detect OTC in actual samples.