| The quantum dots (QDs) exhibit unique physical and chemical properties and excellent luminescent properties, which have a very widespread potential applications in biomedicine, LED, solar batter etc. The quantum dots have attracted the extensive interest and wide concern of the researchers in the fields of biomedicine, materials and optics. Aimed at the important research direction of the quantum dots, the present research condition of quantum dots was summarized, and then the following several works have mainly performed by taking quantum dots preparation, characterization and quantum dots applications in detection of the substances associated with cancer and medicine study as the line of this dissertation.1. Three water-soluble CdTe quantum dots were directly synthesized in water with three different thiol molecules:thioglycolic acid, L-cysteine and cysteamine. The quantum yield of the newly made CdTe quantum dots was doubled through simply light-activated operation. The optical properties of the three quantum dots were characterized by using ultraviolet vision (UV-Vis)spectra and fluorescence emission spectra. The results show with prolongation of the reaction time at the same stabilizer ultraviolet absorption peak and fluorescent emission peak both present obvious red shifts. With the different modifiers at the same reaction time, the quantum dots with different diameters can be gained. That is to say that the quantum dots whose emission wavelength is between 520-580 nm are readily available by controlling the reaction time or using different modifiers. And the cytotoxicities of these three quantum dots have been evaluated, which provides a powerful foundation for further applied research of quantum dots.2. The CdTe QDs-PNA coupling products were prepared through modifying with peanut (Arachis hypogaea) agglutinin (PNA) on the surfaces of the water-soluble CdTe QDs. The coupling products were characterized by using fluorescence, ultraviolet, infrared spectroscopy, SDS-PAGE electrophoresis and thymus cell agglutination test after gel column purification. The coupling products can be used as the QDs fluorescence probe with high optical properties and good bioactivity. Based on the binding properties that PNA strongly recognizes the T antigen, the fluorescent probe was used to detect T antigen highly expressed in the patients with colorectal carcinoma and compared with conventional fluoroimmunoassay labeled by organic dye-labeled fluorescent probe. The experiment results demonstrate that the QDs-PNA fluorescence probes can effectively recognize T antigen and exhibit good sensitivity and exceptional photostability, which would provide a new method in detecting T-antigen and offer a novel way for the diagnosis and prognosis of colorectal cancer. 3. Two CdTe QDs conjugated to agglutinin were prepared through modifying with peanut agglutinin (PNA) and concanavalin agglutinin on the surfaces of the two colors of water-soluble CdTe QDs, respectively. The two coupling products were characterized by using fluorescence, ultraviolet, infrared spectroscopy, SDS-PAGE gel electrophoresis and cell agglutination test after gel column purification. Based on the property that lectin specific binding with different corresponding carbohydrate, these two fluorescence probes were successfully used to label and detect the carbohydrate complexes expressed on the cell surface of lung and liver cancer, which can provide a new method that characterizes different carbohydrate complexes on cell membrane surface.4. With the prepared water-soluble TGA-QDs and L-cys-QDs in chapter two used as fluorescent probes, two novel approaches were developed for sensitive and selective detection of nitrendipine in tablet based on the fluorescence quenching of aqueous CdTe quantum dots by nitrendipine. Meanwhile, different effect factors on the detection were investigated, including buffer concentration, buffer pH, reaction time, quantum dots size and quantum dots concentration. The mechanism of fluorescence quenching of TGA-QDs caused by nitrendipine was further studied. Under the optimized conditions, the linear ranges of the two methods were 1.09-65.4μg/mL and 0.38-77μg/mL, and the detection limits were 0.11μ.g/mL and 0.28μg/mL, respectively. Compared with traditional spectrophotometry for nitrendipine detection, the two methods were simple, fast, and highly sensitive. The results were in good agreement with that of the national standard method in Chinese Pharmacopoeia.5. Seven phenolic acids, ten flavonoids, five anthraquinones and thirteen alkaloids which have an effect on the fluorescence intensity of aqueous CdTe TGA-QDs were investigated in Chinese herbal medicine. The findings indicate that under the same conditions the degree of fluorescence quenching of water-soluble CdTe TGA-QDs increase with increasing acidity of the phenolic acids, flavonoids and anthraquinones; quaternary ammonium alkaloids have a strong influence on the fluorescence intensity of aqueous CdTe TGA-QDs while non-quaternary alkaloids have weak or no influence. The conclusion has been preliminary verification in the extract of the citrus peel of the Nanxiang.6. The effect of the five anthraquinones concentration on the fluorescence intensity of aqueous CdTe TGA-QDs was investigated based on the conclusion that aloe-emodin, rhein, emodin, chrysophanol and physcion can quench the fluorescence of CdTe TGA-QDs. The results show that it has good linearity between the concentration of anthraquinones and relative fluorescence intensity of quantum dots at a certain concentration range. The interaction of emodin and water-soluble quantum dots has been explored by using fluorescence spectra. The results showed that complex substance formed by emodin adsorbed on the QDs leads to the fluorescence quenching of CdTe quantum dots and the way of fluorescence quenching is static quenching. Because the quantum dots fluorescence quenching methods was difficult for the simultaneous analysis of five anthraquinones, a simple and sensitive HPLC with fluorescence detection was developed and validated to a simultaneous analysis of five anthraquinones in P.cuspidatum, Polygonum multiflori, Rhubarb and compound preparation.
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