Investigation Of Nanolabeling Techniques Based On Quantum Dots And Their Toxicity To Cells

The unique optical properties of quantum dots (QDs) make them appealing as novel probes in a variety of biological studies. Water soluble QDs are preferred to hydrophobic QDs in these fields. It is important to synthesize QDs directly in aqueous solution and to enlarge their applications on bioanalytical science. In this thesis, we synthesized QDs in aqueous solution using thioglycolic acid (TGA) as the stabilizer. And the QDs were further used in biological investigations and their biocompatibility were investigated. In brief, this thesis includes the following parts:1. Water-soluble QDs were used to detect antigen CA242 in gastric cancer cells. CdTe QDs with excellent optical spectra were synthesized in aqueous solution, and then successfully modified with sheep anti-mouse antibody and PEG. This kind of fluorescence probe based on the functionalized QDs had been used to detect CA242 in gastric cancer cells and compared with organic dye-based conventional fluoroimmunoassay. The experiment results demonstrated that the QDs-based fluorescence probes can effectively recognize gastric cancer cells and exhibited good sensitivity and exceptional photostability, which would provide a new method in CA242 detection and offer a novel way for the diagnosis and curative effect observation of gastric cancer.2. Based on the FRET between functionalized QDs and Au nanoparticles, a novel method was developed to detect human IgG. The decrease of fluorescence intensity caused by FRET between goat anti-human IgG modified Au nanoparticles and human IgG functionalized QDs was observed. However, when human IgG bound with goat anti-human IgG modified Au nanoparticles, FRET between human IgG functionalized QDs and goat anti-human IgG modified Au nanoparticles was prevented. As the result, the fluorescence intensity of QDs increased subsequently. Based on the quantitative relationship between fluorescence intensity of QDs and the concentration of human IgG, a new method was developed to detect human IgG easily, rapidly and quantitatively. The same principle could be further used to detect other biomolecules.3. The toxicity of CdTe QDs to Hela cells was investigated by MTT analysis and flow cytometry technology. The results were validated using Hoechst 33258 dye-based analysis. All results indicated that CeTe QDs were biocompatible with Hela cells in appropriate concentration rang, which provided useful evidence for further biological applications of QDs.