The Construction Of Chemiluminescence Resonance Energy Transfer(CRET) System Based On CdTe Quantum Dots And Their Application In Analysis

Chemiluminescence resonance energy transfer(CRET) refers to the process of non-radiative energy transfer between the donor of the chemiluminescent reaction and energy transfer acceptor. Quantum dots(QDs) have been widely used as the acceptor of CRET system due to the properties of wide excitation, narrowemission, high quantum yield,size-dependent character and resistance to chemical and photo degradation. CdTe QDs with high photoluminescence quantum yield and stable property were successfully prepared in aqueous phase. This article described a nonenzymatic CRET system for highly sensitive determination of hydroquinone using QDs as acceptor of CRET and studied the detection mechanism. An integrated bienzyme-quantum dot probe was fabricated for CRET sensing. The bienzyme-quantum dot was constructed by conjugating horseradish peroxidase(HRP)and peroxidase(exemplified by glucose oxidase, COx and BOx) to CdTe quantum dot in sequence and it was applied to multiplex imaging.This paper is divided into three chapters.The first chapter briefly describes the property and preparation of QDs, the application of QDs in analysis, and CRET. We combined the advantages of QDs and CRET to establish a QDs-based CRET system for analysis.Chapter two describes a nonenzymatic Co(II)- luminol-H2O2-QDs CRET system for highly sensitive determination of hydroquinone. CdTe QDs was synthesized in the aqueous phase by oil bath with heating under reflux. The UV and transmission electron microscopy was use to characteriz the QDs and the yield of the prepared QDs is up to 30.24%.The factors of CRET system was systematically investigated. It was found that Co(II) catalyzed luminescence of luminol in pH 11.8 and then the energy transferred to CdTe QDs via a CRET mechanism. The catalyst Co(II) can be adsorbed to the surface of QDs by electrostatic force and the Co(II) with small size made the luminol donor quite near to the QDs acceptor, probably accompanying high energy transfer.Hydroquinone is oxidized by H2O2 to benzoquinone which quenches the fluorescence of the QDs. The system was applied to the determination of hydroquinone in water sample. The CRET system was applied in an assay forhydroquinone that has a detection limit of 0.17 nmol/L and the linear range is 0-50nmol/L. The detection limit was lower by factors between 100 and 250,000 than earlier reported methods. The assay was successfully applied to the quantitation of hydroquinone in(spiked) water samples, with recoveries ranging from 95 % to 106 %,and relative standard deviations between 0.5 % and 2.4 %.Chapter three describes an integrated bienzyme-quantum dot probe which was fabricated for CRET sensing and imaging based on luminol chemiluminescence. CdTe QDs was synthesized in the aqueous phase by hydrothermal reaction and the bienzyme-quantum dot was constructed by conjugating horseradish peroxidase(HRP)and peroxidase(exemplified by GOx, COx,BOx) to CdTe quantum dot in sequence by an amide reaction. The bienzyme-quantum dot was characterized by gel electrophoresis / UV spectrometry and transmission electron microscope(TEM). The bienzyme-quantum dot probe combined with luminol to build a bienzyme- QDs-luminol CRET system.The online-H2O2 generation permitted online generation and consumption of H2O2, thus greatly elevating the quenching efficiency of QDs. As a result, the CRET efficiency achieved up to 42%, which was much higher than those current CRET systems. The bienzyme-quantum dot system also allowed long-time imaging(> 60 min), benefiting from persistent CL reaction catalyzed by the bienzymes and the low CL reagent limited in the nanorange. Using the bienzyme-quantum dot system for sensing of glucose, similar CRET phenomena were also observed for BOx and COx-HRP-QDs. Multiplex imaging of cholesterol,benzylamine, glucose was achieved, which can be potentially used for fast screening of cholesterol, benzylamine, glucose. Hence, the bienzyme-quantum dot system for CRET sensing has the advantages of low quenching efficiency of QDs nanorange CL reaction, high CRET efficiency, long-time imaging and potential in multiplex imaging.