The Styudy Of New Type Biosensors On Electrochemilumine Quantum Dots And Its Application

Since Bard's group reported the electrochemiluminescence (ECL) of Si quantum dots(QDs), ECL from QDs has gained particular concern. To date, more and more QDs have been shown to have good ECL properties. For their ECL properties closely related to the size and surfaces states of the material, we can synthsize nanomaterials owing high ECL intensity and good stability by adjusting the structure, composition and dispersion of the nanomaterials.However,for the majority of researchers,there is a certain challenge for preparation QDs and its ECL application. Mainly in the following two aspects: (1) ECL of QDs is relatively weaker than that of traditional ECL luminophanes such as ruthenium Ru(bpy)32+, Which is not conducive to ECL sensor construction?(2) At present, the ECL of QDs is mainly concentrated in cadmium-based semiconductors, and the synthesis of QDs with low toxicity and ECL properties becomes more and more important. The main content of this paper is based on ECL of QDs: (1) The application of solid-state ECLs of shell-core structure CdSe @ ZnS QDs wasstudied in detail. (2) Synthesis of novel QDs with ECL properties by hydrothermal method.We first studied the solid-state ECL behavior of a series of CdSe @ ZnS QDs with different size shell-core structures. And then we demonstrated the effect of TiO2 on ECL strength of QDs with different sizes. The ECL carcinoembryonic antigen biosensor was constructed by selecting the optimum conditions. Based on the elements doping,we synthesized a new type of Eu3+-doped CdSe QDs. Based on the above research background we build a new solid-state ECL sensor with high sensitivity and good stability. In addition, we synthesized and studied the optical properties of perovskite CsPbBr3 NCs in order to use it as a potential ECL emitter.The main contents of this thesis include the following four parts, which are summarized as follows:1. Multicolor electrochemiluminescence of core-shell CdSe@ZnS quantum dots based on the size effectIn this work we successfully realized the systematic study of size-dependent colorful ECL emissions based on core-shell structured CdSe@ZnS QDs in aqueous solutions, whose emission color can be tunable, in principle at will, through the choice of different sizes of cores. The CdSe@ ZnS QDs with different sizes (2.5,4.0 and 5.9 nm) presented novel colorful ECL emissions. The strong ECL intensities allow mobile phone camera to take photos for the ECL images. The ECL emission identical with its FL has been further proven by both the emission spectrum and emission image, indicating the size dependent electronic and ECL roperties of core-structure QDs.2. Double signal amplification sandwich-structured immunosensor based on TiO2 nanoparticles enhanced CdSe@ZnS QDs electrochemiluminescence and the dramatic quenching effect of Au@polydopamine nanoparticlesIn this work, a double signalamplified immunosensor based on the enhanced CdSe@ZnS quantum dots (QDs) electrochemiluminescence (ECL) via TiO2 nanoparticles(TiO2 NPs) and the outstanding quencher of polydopamine (PDA) decorated Au nanoparticles (Au@PDA NPs) for ultrasensitive detection of carcinoembryonic antigen (CEA) has been successfully achieved. The ECL of CdSe@ZnS QDs with different sizes has been investigated carefully,especially cooperation with Ti02 NPs. Au@PDA NPs have been synthesized and characterized by transmission electron microscopy (TEM) and UV-Vis spectrum, which acted as ECL quenchers to label the secondary antibody (Ab2) of CEA to form Ab2/Au@PDA NPs conjugates. The sandwich-structured immunosensor was formed between capture antibody (Ab1) on CdSe@ZnS QDs/TiO2 NPs/glassy carbon electrode, CEA and Ab2/Au@PDA NPs conjugates, resulting in a proportional ECL quenching signal relevant to the CEA concentration. Thus, CEA as a model biomarker has been detected in the linear range from 0.001 to 100 ng mL-1 with a limit of detection of 0.35 pg mL-1 (S/N = 3).3. Electrochemiluminescence sensor for phosphate ions based on europium (?)-modulated CdSe Quantum dotsPhosphate anions are determined based on the electrochemiluminescence (ECL) of CdSe quantum dots (CdSe QDs) capped with 3-mercaptopropionic acid. The ECL gets quenched with the introduction of Eu3+ ions, but it is restored on the further addition of phosphate anions. The sensing mechanism might be due to the strong and specific interaction between phosphate anions and the Eu3+ ions, leading to the releasing of CdSe QDs from aggregates.On the basis of the quenching/recovery ECL behaviors, the ECL sensor offer acceptable sensitivity, high selectivity, and a linear response from 0.1 to 120 mM with a detection limit of 0.03 mM (S/N = 3) for phosphate anions.4. Observing single Au NCs collisions by electrogenerated chemiluminescence amplificationIn this chapter, a kind of Au NCs with good catalytic performance was synthesized using lipoic acid (LA) as a protective agent. The ECL properties of single particles Au NCs were studied with Ru(bpy)32+ and C2O42-. This research can be seen as a pioneer for single-particle ECL from the metal clusters.5. Tunning optical properties of perovskite nanocrystals by supermolecular mercapto-?-cyclodextrinThis work reports a host-guest interaction strategy for systematically manipulating the optical properties of cesium lead halide perovskites nanocrystals (CsPbBr3 NCs) by protectant-mediated mercapto-?-cyclodextrin (SH-?-CD). The fluorescence of CsPbBr3 NCs can be adjusted over 405-510 nm with the quantum yields (QY) of packaged CsPbBr3 NCs maintain 50-90%.In summary, we studied the ECL properties of different types of QDs, and applied to the quantitative analysis of anions and biological analysis based on the change of ECL signal intensity of QDs.