Fabrication And Application Of Electrochemiluminescent Immunosensor Based On Quantum Dots And Gold Nanoparticles

Electrochemiluminescence (ECL) is an effective trace analytical technology due tothe integration of high sensitivity and controllability of potential. Immunosensors arebiosensors based on specific antigen-antibody interactions, which combined the highsensitive sensor technology with specific immunoreaction. Combining of the above twotechnologies, ECL immunosensor will have broad application prospects. In thisdissertation, the water-soluble CdSe quantum dots have been prepared by usingthioglycollic acid (TGA) as the stabilizer in aqueous phase. Gold nanoparticles (GNPs)were synthesized by FRENS method by using trisodium citrate as reductant. Using thiskind of quantum dots and GNPs, we construct different QDs ECL systems for the detectionof clenbuterol (CLB) and phenylethanolamine A (PA) in the food, respectively.The dissertation includes four chapters:In chapter1, the significance and background knowledge of this dissertation havebeen introduced with the emphasis on the following aspects, which are the properties ofelectrochemiluminescence (ECL), funtamental principle of ECL immunoassay system andthe application of QDs in the ECL immunoassay.In chapter2, the water-soluble quantum dots have been prepared by using TGA asstabilizer. The optical properties of CdSe have been studied by UV-Vis absorption andfluorescence spectroscopy, and its size properties have been characterized withhigh-resolution transmission electron microscope and dynamic light scattering. Goldnanoparticles (GNPs) were synthesized by Frens’s method. The optical properties of GNPswere studied by UV-Vis absorption, and scanning electron microscope (SEM) was used tocharacterize its size properties.In chapter3, we designed a cathode QDs ECL immunosensor by layer by layermodification techniques. The coating antigen, which was immobilized on the electrode byGCE/GNPs architecture, could compete with the CLB in the incubation solution to react with the limited binding sites of the QDs-antibody. Moreover, GNPs were creatively usedto accelerate the electron transport between the surface of electrode and QDs, which couldefficiently enhance the ECL intensity of the immunosensor. The ECL intensity of theimmunosensor decreased with the concentration of the clenbuterol standard in theincubation solutions. Thus an ultrasensitive method for detection of clenbuterol has beenestablished, and the limit of detection (LOD) for clenbuterol is0.0084ng/mL. Theimmunosensor shows good stability and reproducibility, it has been used for detecting ofclenbuterol in practical samples with satisfactory results.In chapter4, in the cathodic CdSe QDs-potassium peroxodisulfate ECL system, theECL emission will be gradually decreased after adding phenylethanolamine A (PA) due tothe competitive immunoassay. Thus, a novel, simple, rapid and sensitive method fordetection of phenylethanolamine A has been established. The detection ofphenylethanolamine A in real samples and the detection of interference substance havealso been discussed in detail.