Electrochemiluminescence Behavior And Sensing Application Of All Inorganic Perovskite Quantum Dots At Bipolar Electrode

All inorganic perovskite nanocrystals have excellent optical and electrical properties,and have been widely concerned in many fields.However,its fragile stability in polar solvents limits the application of such materials in analysis and detection,which needs further study.Electrochemiluminescence（ECL）analysis technology integrates the advantages of chemiluminescence and electrochemistry,and has been widely used.At the same time,the detection channel and the reporting channel of the closed bipolar electrode（BPE）system without mutual interference can avoid the interference between polar solvents and luminous reagents.In this paper,based on the characteristics of the BPE and the aptamer for specific recognition,the ECL and fluorescence visualization sensing platform with good analytical performance have been developed with all inorganic perovskite nanocrystals as luminescent materials.The analytical detection of H₂O₂,tetracycline（Tc）and T-2 toxin has been realized respectively.The specific research contents are as follows:1、All-inorganic perovskite quantum dots CsPbX₃（X=Cl,Br,I）have emerged as a new class of semiconductor nanocrystals,but the stability of CsPbX₃ quantum dots（QDs）against the destruction in polar solvents is still a significant challenge.Considering that most of the targets in analytical chemistry,especially those for biological detection,exist in aqueous media,this weakness seriously hampered the wide applications of CsPbX₃ QDs in practical applications.In this study,a closed BPE was introduced to broaden the application field of perovskite QDs in water systems.Based on the principle of charge conservation in the electrode reactions at both ends of BPE,the concentration of H₂O₂ in aqueous medium can be detected by the ECL intensity of CsPbBr₃ QDs in organic solution.Thus,the analysis of aqueous system with all-inorganic perovskite CsPbBr₃ QDs was successfully realized by the closed BPE chip with stable ECL performances for the first time.2、The overuse of antibiotics seriously threatens human health and pollutes the ecological environment,so it is necessary to develop simple,sensitive and rapid detection methods.In this study,an all-inorganic perovskite CsPbBr₃ quantum dot was combined with a closed bipolar electrode and a 3D printed microcells to design an ECL aptamer sensor for sensitive Tc detection.CsPbBr₃ QDs/EA were loaded on anode microcell,served as the ECL active materials,and Tc solution were loaded on cathode microcell.The combination of Tc and aptamer will change the cathode impedance.Based on the principle of charge conservation,the quantitative determination of Tc was successfully realized by recording the ECL intensity of CsPbBr₃ QDs,and it was used in the actual sample determination.The constructed aptamer sensor exhibited excellent and stable detection performance with wide linear range and low detection limit.3、CsPbI₃（CPI）QDs were synthesized by hot injection method as luminescent materials,which were modified with Prussian blue（PB）in the reporting cells of BPE.CQD/g-C₃N₄/TiO₂（CCNT）composites were synthesized by solvothermal method and impregnation-precipitation method as photoactive materials,modified on BPE sensing cells,and chemically bonded to T-2 toxin aptamers.Because the fluorescence spectrum of CPI overlaps with the PB absorption spectrum,the energy transfer between the two causes the fluorescence quenching of CPI.Under visible light,photogenerated electrons generated by CCNT were transferred to PB,which was converted to Prussian white（PW）,causing the recovery of CPI fluorescence.However,the binding of T-2toxin and aptamer increased the impedance,which affected the transition from PB to PW.Therefore,the fluorescence intensity of the reporting cells used as an indicator of target toxin concentration,and an efficient fluorescence visualization biosensor based on closed BPE had been successfully constructed.Based on the good fluorescence properties and electrochromic principle of CPI QDs,this biosensor had been successfully applied to the detection of T-2 toxin and to the detection of real samples in beer.The design of the sensor opens up a new possibility for the follow-up application of all inorganic perovskite.