Application Of β - Cyclodextrin Modified CdTe Quantum Dots In Analysis

Due to the excellent photoelectric properties, quantum dots become popular in the study of nanometer materials, and thus are widely used in physics, chemistry, electronics, especially in biology as the fluorescence probes. Target analytes can be detected sensitively by designing fluorescent probes. So far, it has been reported that quantum dots sensor can be applied in the field of ion detection, molecular recognition, immune analysis, biological imaging, and so on. The research contains the following three parts:Part one:IntroductionFirst of all, the basic concept of quantum dots were summarized, the optical characteristics of quantum dots and light-emitting principle are illustrated. Then synthesis and surface modification methods for quantum dots are introduced. Furthermore, the applications in the field of quantum dots in the biological analysis have been introduced briefly. Finally, the purposes and significance of the research are put forword.Part two:a-Glycosidase activity assay and inhibitor screeningDiabetes mellitus, which is a serious and chronic disease associated with abnormally high blood glucose levels, has become a global health problem. In this study, a fluorescence method was established for a-glucosidase activity assay and inhibitor screening based on β-CD-QDs.p-Nitrophenol, the hydrolysis product of the a-glucosidase reaction, could quench the fluorescence of β-CD-QDs via electron transfer process, leading to fluorescence turn off, whereas the fluorescence of the system turned on in the presence of a-glucosidase inhibitors. Taking advantage of the excellent properties of quantum dots, this method provided a very simple, rapid and sensitive screening method for a-glucosidase inhibitor. Two a-glucosidase inhibitors, 2,4,6-tribromophenol and acarbose, were used to evaluate the feasibility of this screening model, and IC50 values of 24 μM and 0.55 mM were obtained respectively, which were lower than those previously reported. The method may have potential application in screening of a-glucosidase inhibitors.Part 3:Fluorescence detection for dopamineDopamine is a kind of catecholamine neurotransmitters, and it exists widely in peripheral nerve and nerve system, which is associated with many debilitating diseases. Therefore, sensitive and rapid detection of dopamine is extremely significant for clinical diagnosis of dopamine. In this chapter, we use β-CD-QDs as fluorescent probes for the detection of dopamine. In the alkaline solution, the dopamine can be oxidated to dopamine-quinone, which can enter the cavity of β-CD, and then electron transfer occurs between dopamine-quinone and quantum dot surface, thus the fluorescence of QDs are quenched. Base this mechanism, we establish the dopamine fluorescence detection method. The linear range of dopamine ranges from 1.0 ×10-7 to 2.0×10-5 mol/L, and detection limit obtained is 38.6 nmol/L. Compared with traditional methods, this sensitivity fluormetric method is simple, fast and easy-operation.