Study On Quantum Dot - Hydrogen Peroxide Chemiluminescence System

Semiconductor nanocrystals (quantum dots, QDs) exhibit unique nature such as size-dependent emission, narrow emission peak,broad excitation spctrum, resistance to photo-bleaching and present particular properties such as high selectivity and good compatibility. Thus, it has gained wide popularities in biomedical imaging and fluorescence biosensors. In recent years, the practical application of chemilumiescence (CL) of QDs has been increasingly paid attention to. The use of QDs as CL emitter is a topic of considerable interest in CL research field. In this work, we established a new method. It is about the enhancement of CL of CdTe QDS-H2O2system. We explored the main effects on QDs CL intensity.Thesis consists of review and research section. The review section describes the basic conception and application of QDs. The research section is as follows.1. Enhanced chemilumiescence of CdTe quantum dots-H2O2by G-quadruplex-hemin DNAzyme DNAzymeIn this study, it was found that G-quadruplex-hemin DNAzyme could effectively enhance the CL emission of CdTe quantum dots (QDs)-H2O2system, whereas HRP could not enhance the CL intensity. The CL enhancement mechanism was investigated, and the CL enhancement was supposed to originate from the catalysis of G-quadruplex-hemin DNAzyme on the CL reaction between CdTe QDs and H2O2. Meantime, compared with CdTe QDs-H2O2CL system. H2O2concentration was markedly decreased in G-quadruplex-hemin-QDs-H2O2CL system, improving the stability of QDs-H2O2CL system. The QDs-based CL system was used to detect sensitively CdTe QDs and G-quadruplex-hemin DNAzyme (as biologic labels). This work gives a path for enhancing CL efficiency of QDs system, and will be helpful to promote the step of QDs application in various fields such as bioassay and trace detection of analyte.2. Effect of capped reagents and sizes on water-soluble quantum dotswe detailedly studied the effect of QDs size and the effect of QDs capped reagents in G-quadruplex-hemin-QDs-H2O2CL system. CdS QDs capped with glutathione (GSH), CdTe QDs capped with different capped reagents (GSH and thioglycolic acid (TGA)) were synthesized in aqueous solution with different sizes. In basic conditions, hydrogen peroxide could directly oxidize these water-soluble QDs to produce CL emission, which could be enhanced by G-quadruplex-hemin DNAzyme. The effects of different capped reagents and sizes on the CL intensity of these QDs were studied. Compared with their corresponding fluorescence (FL), we can generalize the main effects of these QDs CL intensity and the relationship between their FL intensity and CL intensity. This work provides a theoretical basis for designing and synthesizing strong chemiluminescence QDs.