Synthesis Of Quantum Dots And Their Application In ATP Detection

Quantum dots (QDs), also known as semiconductor nanoparticles, are becoming aclass of important fluorescent labels due to their unique optical performance, such asbroad absorption, narrow emission, multi-colored emission, and high resistance tophotobleaching. Synthesis of quantum dots is a hotspot in quantum dots study for years;with in-depth study, supplementary approaches such as ultrasound, light, and microwaveradiation were introduced into the synthesis of QDs. Meanwhile, as the growing potentialof the near-infrared fluorescence imaging techniques-one of the most important opticaldetection method-highlights in deep tissue imaging and noninvasive in vivo detection,research on synthesis of the near-infrared QDs have attracted much more attention overthe recent years. As for the applications of QDs, to design QDs-based biosensors for thedetection of biological molecules, which take advantage of the strength of fluorescencedetection such as high sensitivity, strong selectivity, and simple operation, is of greatsignificance in the study of molecular interactions and medical diagnosis.This thesis mainly focuses on the synthesis of quantum dots in aqueous phase andorganic phase, the design of QD/aptamer-based chemiluminescence resonance energytransfer (CRET) biosensor, and its application in ATP detection. The main results aresummarized as follows:(1)Water-soluble CdTe QDs with excellent optical properties were synthesized byhigh-pressure microwave radiation, of which fluorescent emission covers540~605nm.The influence of microwave radiation on the CdTe nucleation and growth rate wasinvestigated, and the results indicated that microwave radiation significantly increased thematuration rate of CdTe in the closed reaction system with high temperature and pressure.This promoting effect mainly contributed in the early stage of reaction that can be used forrapid synthesis of CdTe QDs. In addition, maturation rate of QDs with GSH as ligands was higher than that with MPA as ligands; pH or temperature rising within certain rangewould speed up the reaction process when synthesized CdTe QDs by microwave radiation.(2)The effects of two different group of coordinating agents on the capping process ofCdSe were studied in the synthesis of CdTe/CdSe QDs. Near-infrared QDs in the range of650-800nm were successfully prepared. When TOPO/HDA was adopted as coordinatingagents, emission spectrum of CdTe/CdSe QDs entered the near-infrared range, butquantum yield of which decreased accompanied with the coating of CdSe. On the contrary,when took ODPA/TOP as coordinating agents, the quantum yield has a gradual increasingprocess, and the maximum reached to40%. However, perhaps owing to the excesslystrong coordination ability of ODPA/TOP, near-infrared QDs were hardly synthesized. Inaddition, PEGylation of QDs surface was preliminarily discussed.(3)A QD/aptamer based CRET biosensor was designed, where horseradish peroxidase(HRP)-catalyzed luminol acts as donor and QD acts as donor, for the detection of ATPmolecule. In the presence of ATP, along with the strucural changes in the aptamer, QD andHRP begin to close enough to make CRET happen between them after adding reactionbuffer. Then the ATP detection was successfully realized by detecting the fluorescence ofQDs. This work introduced CRET into the construction of biosensors, and would havebroad application aspects in the quantitative detection of such as cellular and biologicalmetabolites, enzymes and study of molecular interaction mechanism.