Construction And Application Of Quantum Dots Based Electrochemiluminescent Immunosensor With Simple Structure And Dual Amplifying

Electrochemiluminescence immunoassay combines the advantages of the electrochemiluminescence (ECL) and the immunoassay. As a new tool for analysis, electrochemiluminescence immunoassay possesses the superiorities of high sensitivity, favorable specificity, and characteristics of quick and easy detection. This method has been widely applied in different fields. In this paper, a water-soluble quantum dots, positively charged graphene and gold nanoparticles (GNPs) are successfully prepared. On the basis of these materials, electrochemiluminescence immunosensors with simple structure and with dual amplifying are successfully designed, which open new avenues of detecting food additive residue and heavy metal ions based on QDs ECL in immunoassays.The dissertation includes five chapters:In chapter 1, the background and basic theory of electrochemiluminescence immunoassay are presented. Moreover, novel types of electrochemiluminescent label and electrochemiluminescence immobilization support, such as semiconductor nanocrystals, porous noble metals, graphene, TiO2, Immunoassay nanotube arrays, are discussed.In chapter 2, TGA functionalized water-soluble quantum dots, gold nanoparticles (GNPs), and positively charged graphene have been prepared. UV-Vis absorption, scanning electron microscope (SEM), and High-resolution transmission electron microscopy (HRTEM) are applied for characterization of these materials.In chapter 3, a rapid and ultrasensitive electrochemiluminescence (ECL) competitive immunoassay based on CdSe quantum dots (QDs) and the shorter chain as possible (cysteamine and glutaraldehyde) has been designed for the detection of salbutamol (SAL). Cysteamine and glutaraldehyde made coating antigen immobilize well on the gold electrode surface through the reaction between functional groups, which brought about the simplicity of the immunosensor to some extent. With a competitive immunoassay format, the detection limit is 0.0056ng/mL, which will extend the application of QDs ECL in immunoassays and open new roads for the detection of food additive residue in the future.In chapter 4, we have designed a rapid and ultrasensitive ECL competitive immunoassay for the determination of mercury (â…¡) ion based on the use of CdSe quantum dots (QDs), methylmercury-6-mercaptonicotinic acid-ovalbumin as coating antigen and specific monoclonal antibodies (mAbs) against Hg (â…¡). The latter is quite selective for Hg (â…¡). The coating antigen was simply immobilized on the surface of a gold electrode via reaction between the functional groups of cysteamine and glutaraldehyde. The mercury (â…¡) ions in a sample and the coating antigen compete for binding sites of QD-labeled monoclonal antibody which binds specifically to Hg (â…¡) ions. The detection limit is 6.2pg/mL, and this is the first report on an ECL immunoassay for Hg (â…¡) based on a specific monoclonal antibody.In chapter 5, a novel electrochemiluminescent label based on the combination of poly (diallyldimethylammonium chloride) (PDDA)-protected graphene (P-GR), CdSe QDs, GNPs has been successfully prepared. The P-GR acts as the excellent supporting material for signal amplification in ECL sensors. The characterizations of the label are presented via UV-Vis absorption, scanning electron microscope (SEM), and High-resolution transmission electron microscopy (HRTEM).