The Preparation And Application Of The Hydrophilic CdS Quantum Dots

Semiconductor quantum dots have unique optical properties. The potential application of CdS quantum dots in several fields such as biochemistry, material chemistry, medicament chemistry and so on, have generated great research interest to people. Compared to conventional organic dyes, quantum dots are advantageous over fluorescent dyes because of their wider excitation spectra, narrower emission spectra, tunable emission color, high quantum yield and long-term photostability. Therefore, quantum dots can have been used as fluorescent probe to detect some inorganic ion and small organic molecules successfully. In the present paper, the emphases of the studying rest with CdS quantum dots as luminescent sensor for the determination of some small organic molecules in medication and human fluids.(1)Dispersive CdS quantum dots are synthesized in aqueous solution. The different cationic surfactants such as sodium hexametaphasphate (HMP) and thioglycolic acid (TGA) are used as steady reagents, and HMP-capped CdS QDs and thiol-capped CdS QDs are synthesized. Simultaneity, the qualification of the synthesis is optimized.(2)HMP-capped CdS QDs are used as biosensor for uric acid determination. The results indicating that, in the phosphate buffer solution at pH=6.50, uric acid can observably quench the fluorescence of CdS QDs in the presence of cationic surfactant CTAB. The hydrophilic CdS QDs are used successfully for the determination of uric acid in human fluids. The method is rapid, simple and efficient, and has good selectivity.(3)The hydrophilic thiol-capped CdS quantum dots are used as a novel sensitive and selective fluorescent probe for tetracycline antibiotic medication. In the phosphate buffer solution at pH=4.02 and at pH=3.60 separately, tetracyclines (TC) and terramycins (OTC) can quench the fluorescence of thiol-capped CdS QDs directly. Under optimal conditions, The method is applied to determine and reclaim TC and OTC in tablets and human fluids, and the results are satisfactory. Simultaneity, the possible mechanism of reaction is also discussed.