Preparation And Application Research Based Electrochemiluminescent Sensor Of CdSe Quantum Dots

In this study,Water-Soluble CdSe and CdSe@ZnSe quantum dots（QDs）were synthesized with the hydrothermal method,the designed electrochemical luminescence（ECL）sensors were prepared by coating directly or layer by layer modification techniques.The main experiment results below:Water-soluble CdSe QDs with different relux reaction time were synthesized with the hydrothermal method.The CdSe QDs were characterized by UV-absorption,photoluminescence spectroscopy,X-ray diffraction and Fourier transform infrared spectroscopy method.As the relux reaction time increases,the absorption edge experiences a shift towards larger wavelengths with a simultaneous increase of fluorescence intensity and its lifetime.CdSe QDs solutions with excellent fluorescence properties were obtained.Based on the above work,Water-soluble CdSe@ZnSe core-shell QDs were synthesized with the hydrothermal method.Compared with CdSe QDs,the absorption edge of CdSe@ZnSe core-shell QDs absorption edge experiences an obviously red shift with a simultaneous increase of fluorescence intensity and its lifetime.The results show that when the CdSe quantum dots are coated with a layer of ZnSe,the surface defects of CdSe quantum dots are passivated and compensated to a certain extent.The core shell of CdSe@ZnSe QDs have better fluorescence properties than single core of CdSe QDs.The CdSe QDs were immobilized on the surface of the gold electrode and the CdSe modified electrode was prepared.The ECL properties of this modified electrode was studied.The CdSe QDs modified gold electrode showed enhanced ECL intensity when compared to bare gold electrode in alkaline solution.When folic acid（FA）were added to the new ECL system,the ECL intensity were further enhanced.Further,the CdSe QDs were used to design an ECL immunosensor for the detection of FA was developed.Several experiment factors,such as pH of buffer solution,the concentration of luminol and scan rate were selected.Under optimized conditions,the ECL signal intensity is linearly related to the concentration in the range from 1.0×10^-66 to 1.1×10^-4mol L^-1,with a lower detection limit of 3.3×10^-7 mol L^-1（S/N=3）.The glucose oxidase was immobilized on the surface of GO-CdSe compound coating glass carbon electrode by the self-assembled technique.The modified electrode was characterized by UV-absorption,photoluminescence spectroscopy and X-ray diffraction.The ECL properties of this modified electrode was studied.When glucose were added to the mixture solution,the ECL signal intensity is higher than that of GO-CdSe/GOx self-assembled electrode.Catalysis of glucose oxidase to produce the H₂O₂,and H₂O₂ can enhance ECL intensity of luminol system,thus a new method for detecting the content of glucose was established.Titanium dioxide-CdSe compound（TiO₂-CdSe）was prepared by ultrasonic mixing method.5μL of TiO₂-CdSe compound solution was dropped on the gold electrode,and the modified TiO₂-CdSe electrode was prepared.The modified electrode was characterized by UV-absorption.FL Spectrometry and Cyclic Voltammetry.The ECL properties of this modified electrode was studied.The result shows that the ECL intensity of TiO₂-CdSe modified electrode is higher than CdSe modified electrode in mixture solution（containing 4.0 mM Luminol in pH 10 PBS solution）.When lead nitrate were added to the mixture solution,the ECL signal intensity is higher than that of GO-CdSe compound.Furthermore,the TiO2-CdSe QDs were used to design an ECL immunosensor for the detection of Europium Ions was developed.An Ru（bpy）₃²⁺/PVP/CdSe@ZnSe ECL immunosensor was assembled with Ru（bpy）₃²⁺as the basic luminescent regent,PVP film as the adsorbent,and CdSe@ZnSe as the modifier by self-assembled technique.The ECL properties of this modified glass carbon electrode was studied.The results showed that this modified electrode can enhance ECL intensity when compared with Ru（bpy）₃²⁺/PVP modified electrode.When Chrysin were added to the mixture solution(containing 0.01 mol L^-1 TprA in pH 11PBS solution),Furthermore,the Ru（bpy）₃²⁺/PVP/CdSe@ZnSe were used to design an ECL immunosensor for the detection of Chrysin was developed.The preparation conditions such as pH,polymer,the volume of PVP and the concentration of TprA were investigated.Under optimized conditions,the ECL signal intensity is linearly related to the Chrysin concentration in the range from 1.4×10^-66 to 1.4×10^-6 mol L^-1,with a lower detection limit of 3.3×10^-8 mol L^-1（S/N=3）.