| Quantum dots (QDs) exhibit many physical and chemical properties due to the quantum confinement effect and surface effect. Since Bard's group reported the electrochemiluminescence (ECL) of Si QDs, ECL from QDs has gained particular concern. But the surface of bare QDs is made up of a lot of defects which influences its luminous efficiency. To remove these defects and improve the optical properties, QDs with a narrower band gap as cores have been passivated with a wider band gap QDs which have similar crystal structure. In particular, the optical properties of the resulting core/shell QDs are found to be controlled by adjusting the thickness of shells. Currently, magnetic separation has been widely applied in the separation and purification of various biological substance, such as enzyme, protein, cell and nucleic acid. QDs composited with magnetic materials will provide a promising application for biomedical research. In addition, our group studied electrochemiluminescence of 2-(dibutylamino)ethanol/oxygen, but more research need to be carried out. Based on these, main contents and results in this paper are listed as follows:1.CdSe quantum dots as cores capped with ZnSe shell (CdSe/ZnSe QDs) via a simple and eco-friendly strategy have been synthesized in aqueous solution for the first time. The electrochemiluminescence (ECL) of CdSe/ZnSe QDs was greatly enhanced compared to that of CdSe QDs. In particular, the ECL properties of the resulting CdSe/ZnSe QDs were found to be controlled by adjusting the thickness of ZnSe shells. The maximum ECL intensity of as-prepared CdSe/ZnSe QDs was obtained by controlling the amount of CdSe core to ZnSe shell at the ratio of 1:3. The strong ECL intensity can be observed by naked eyes and recorded by the camera of a common mobile phone. Its ECL spectrum was constant with its photoluminescence spectrum due to the core/shell structure. The ECL sensor based on CdSe/ZnSe QDs film modified glassy carbon electrode could accurately quantify dopamine from 10.0 nM to 3.0 ?M with a detection limit of 3.6 nM benefiting from the enhanced ECL intensity. Based on the synthesis of CdSe/ZnSe QDs, the solvothermal reduction method has been used to successfully produce Fe3O4. In the following process, Stober's method was adopted to grow a further silica protection layer on the magnetite cores by hydrolysis of TEOS. CdSe/ZnSe QDs prepared were crosslinked with Fe3O4/SiO2. ECL of CdSe/ZnSe QDs-Fe3O4/SiO2 was very high although lower than CdSe/ZnSe QDs.2.Based on strong anodic electrochemiluminescence (ECL) of dissolved oxygen with 2-(dibutylamino)ethanol (DBAE), the effects of halide ions on O2/DBAE system were investigated. It was found that ECL of this system was neither enhanced nor decreased when the bromide ions and chloridions were added. However, ECL of O2/DBAE system could be strongly quenched by the iodide ions. Quenching effect of iodide ions could be explained that iodide ions may be oxidized to iodine when the voltage was large enough, then iodine deposited on the surface of the electrode caused quenching of electrochemiluminescence. |
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