Electrochemiluminescence Of AgInS And Cu:InP NCs And Its Study Of Biosensing Application

Electrochemiluminescence（ECL）is a combination of electrochemical and photoluminescence analysis technology.It is a new type of analysis method that can show the advantages of fast analysis and detection,simple operation method and high sensitivity detection limit.ECL technology makes up for the shortcomings of traditional photoluminescence technology,so that the background noise during the sensing experiment is greatly reduced,and it has good application value in the field of immunoassay.However,with the increasing awareness of environmental protection,researchers have discovered that traditional and widely used binary quantum dots such as Cd S,Cd Se,Cd Te,Pb S and Pb Se quantum dots contain environmentally toxic Cd,Pb and other heavy metal elements,which are not conducive to environmental protection.Therefore,the innovative work of this paper is mainly to synthesize silver indium sulfur quantum dots and copper-doped indium indium phosphide quantum dots with low toxicity and excellent optical properties.The synthesized quantum dots are used as luminescent labels to construct sandwich immunosensors for biosensing applications.The main contents are as follows:（1）Using AgInS₂/ZnS nanocrystals（NCs）containing elements as markers,a near-infrared（NIR）electrochemiluminescence immunosensor was constructed for the highly sensitive detection of carbohydrate antigen 125（CA125）.The core/shell structure of silver indium sulfur/zinc sulfide quantum dots（AgInS₂/ZnS NCs）can be easily prepared by aqueous phase synthesis experiments.It also has high photoluminescence quantum yield（PLQY）of up to 61.7%,high degree of monodispersity,larger water solubility,and good biocompatibility.Since AgInS₂/ZnS NCs can be oxidized by electrochemically injecting holes into the valence band at+0.84 V,the monodisperse AgInS₂/ZnS NCs in the solution and the AgInS₂/ZnS NCs fixed in the sandwich immune complex both showed effective redox ECL near 695 nm when tri-n-propylamine（TPr A）was the anode co-reactant.With CA125 as the test substance,the ECL intensity of AgInS₂/ZnS NCs immobilized in the sandwich immune complex kept linear as the concentration of CA125 increased from 5×10^-6U/mL to5×10^-3U/mL The detection limit（LOD）is 1×10^-6U/mL and the signal-to-noise ratio is3（S/N=3）,indicating that the immunosensor constructed in this study provide a more effective detection method for diagnosis and treatment of early-stage ovarian cancer.（2）Using copper chloride（Cu Cl₂）as the dopant in the organic phase,the copper-doped indium phosphide quantum dots（Cu:InP/ZnS NCs）with a maximum emission wavelength of 680 nm were synthesized by the nucleation growth method.Subsequently,11-mercaptoundecanoic acid（MUA）was used to achieve the successful transfer of quantum dots from the organic phase to the aqueous phase through a ligand conversion experiment.It is water-soluble and can be applied to the field of biosensing.This experiment uses TPr A as the anode co-reactant to detect the ECL of its quantum dots,and uses Cu:InP/ZnS NCs as the luminescent label to construct an immunosensor with prostate specific antigen（PSA）as the detected substance.The experimental results showed that the linear range of detecting PSA concentration was 0.1 pg/mL～1 ng/mL,the detection limit（LOD）is 0.02 pg/mL,and the signal-to-noise ratio is 3（S/N=3）.Finally,the constructed sensor was evaluated for specificity and reproducibility.It shows that the immunosensor constructed in this work has high sensitivity and is expected to be applied in the field of early diagnosis of prostate cancer.