Synthesis Of Quantum Dots And Gold Nanoparticles And Their Application

Quantum dots?QDs? are widely applied in analytical chemistry due to their unique optical properties, such as high quantum yield, long fluorescent life, broad excitation spectrum, narrow-band emission spectrum, excellent chemical stability and biocompatibility. Gold nanoparticles?AuNPs? as optical probes are widely used in biological, chemical and other fields owing to some special physical and chemical properties, especially the high extinction coefficient and a visual inspection. Aptamer is a small piece of oligonucleotide sequence through an in-vitro selection process, highly specific binding to the target substance, and can be adsorbed onto the surface of negative gold nanoparticles to increase its stability, as well as causing aggregation of positive gold nanoparticles, which can greatly increase the selectivity and sensitivity of the experiment.In this thesis, the work of the preparation, characterization and application of different QDs and AuNPs was completed. The main contents include the following parts:?1? The mercaptoacetic acid stabilized QDs was synthesized and it was characterized by the UV-visible spectrophotometer, fluorescence spectroscopy, Zeta potential and dynamic light scattering?DLS?. A label-free lysozyme detection method based on quantum dot and aptamer was developed: Malachite green?MG? can be noncovalently self-adsorbed on QDs, which induces fluorescence quenching of QDs; MG is more likely to interact with aptamer; lysozyme-binding aptamer?LBA? can interacted specifically with lysozyme. The experimental results show that lysozyme could be detected in the concentration range of 0.1 to 60 nmol L^-1 in the pH8.0 Tris- HCl buffer system. The recovery rate in the real samples?saliva? was 93.2%–101.5%.?2? The negative citric-AuNPs and negative GSH-CdTe QDs were prepared and a simple and sensitive label-free sensing strategy for the visual and fluorescent detection of lysozyme has been developed based on the efficient inner filter effect?IFE? of AuNPs on the fluorescence of CdTe QDs. The experimental results show that a good linear relationship between the ratio of fluorescence intensity F/F0 and the concentration of lysozyme was obtained in the range of 4.0 to 60 nmol L^-1, with a detection limit of 3.0nmol L^-1. The recovery rate in the real samples?tears? was 94.6%–102.5%.?3? The positive cysteamine-AuNPs and negative GSH-CdTe QDs were prepared and a label-free aptamer sensing strategy for the visual and fluorescent detection of thrombin has been developed based on the fluorescence resonance energy transfer?FRET?of AuNPs on the fluorescence of CdTe QDs. The experimental results show that a goodlinear relationship between the fluorescence intensity F/F0 and the concentration of thrombin was obtained in the range of 10 to 80 nmol L^-1. The recovery rate in the real samples?tears? was 103.3%–108.5%.