Preparation Of Soluble Zero-dimensional And One-dimensional Semiconductor Nanomaterials And Their Applications-in The Analysis Of Znse, Cdse,

Semiconductor nanomaterials have attracted extensive interest because of their variety of size- and shape-dependent optical and electrical properties. Most attention has been paid to quantum dots (QDs). QDs have become an important photonic tool in the past two decades due to their unique properties, such as high chemical stability, resistance to photodegradation, readily tunable optical properties, narrow-band emission and broad excitation spectra. In rencent years, QDs have been successfully used as fluorescent probes in chemical analysis and cellular image, lable and sense.In view of optical and biological applications, semiconductors with one-dimensional (1D) nanostructures have attracted considerable attentions recently due to their increasingly recognized advantages and the quite different quantum confinement energies. For example, Mikhail Artemyev synthesized the DNA-CdSe nanorod complexes and its polarized micro-PL imges. Recently, biological assembly of nanocircuit prototypes from protein-modified CdTe nanowires atrracted extensive attention. Water-soluble CdTe nanowires can be used as fluorescent probe to detect copper ions. Most recently,the new study confirmed that semiconductor nanorods was the brighter fluorescent probe compared to semiconductor nanoparticles. However, 1D semiconductor nanomaterials were difficult to be synthesized in aqueous media. Therefore, the exploration of water-soluble 1D semiconductor materials as fluorescent probes for biological samples and cells remains at a very early stage.There are four chapters in this dissertation:Chapter one: Reviews were given firstly on the application of QDs in fluorescence analysis and the synthetic methods of 1D semiconductor materials. The novel optical properties and potential applications of 1D semiconductor materials were discussed.Chapter two: Water-soluble photoluminescent and stable ZnSe nanorods (NRs) were firstly synthesized in aqueous media at low temperature using thioglycolic acid and L-cysteine as mixed ligands. The X-ray power diffraction (XRD), tranmission electron microscopy (TEM), High-resolution electron microscopy (HRTEM), photoluminescence and confocal microscopic images were used to characterize the as-synthesized ZnSe NRs. The detailed formation mechanism and phosphate buffer of different pH value on the PL intensity were also discussed. These nanorods were functionalized on their surface with carboxylic group and amino group and photoluminescence was stable for half a year at least, which made them use in biological application possible.Chapter three: Water-soluble photoluminescent and stable CdSe nanorods (NRs) were firstly synthesized in aqueous media at low temperature using thioglycolic acid and L-cysteine as mixed ligands. The XRD, TEM, HRTEM, photoluminescence and confocal microscopic images were used to characterize the as-synthesized CdSe NRs. The detailed formation mechanism and phosphate buffer of different pH value on the PL intensity were also discussed. These nanorods were functionalized on their surface with carboxylic group and amino group and photoluminescence was stable for half a year at least, which made them use in biological application possible.Chapter four: Reported herein was the design of a fluorescence resonance energy transfer (FRET)-based method for specific detection of glucose that made use of gold-quenched fluorescent CdTe QDs as the probe. CdTe ODs modified with apo-GOX were used as the donor, while monodisperse gold nanoparticles (Au NPs) modified acting as a nano-quencher. Au NPs possessing high extinction coefficient functioned as excellent fluorescent quenchers in CdTe QDs-Au NPs composites. FRET switched off by a factor of glucose competing with dextran to affinity with apo-GOX, which restored the CdTe QDs of the quenched fluorophore to be followed by spectrofluorimetry.