Aqueous Synthesis of Near-Infrared CdTe Quantum Dots for Biothiols Detection in Biological Fluids

作者：Cui Xiaoteng^*; Lv Yuyang; Liu Ying; Wu Boyue

来源：Acta Chimica Sinica, 2014, 72(1): 75-82.

DOI：10.6023/A13090931

• quantum dots
• aqueous synthesis
• near-infrared fluorescence
• biothiol detection

As well known that conventional aqueous synthesis of the near-infrared (NIR) CdTe quantum dots (QDs) using thiol ligands as capping reagents is usually very time-consuming. To overcome this defect and prepare NIR CdTe QDs, we present a fast and facile route in aqoueous phase under atmospheric pressure using L-cysteine (L-Cys) as capping reagents. The influences of various experimental conditions on the growth rate and luminescent properties of the obtained CdTe QDs have been systematically investigated, including Te-to-Cd ratio, L-Cys-to-Cd ratio and pH value. The experiment results suggested that lower ratio of Te:Cd or L-Cys: Cd and high pH value would markedly shortened the reaction time. Furthermore, the obtained QDs were used as a kind of NIR fluorescent probes for thiol detection in biological fluids. The change in the fluorescence intensity of the NIR CdTe QDs in the presence of 5.0 mu mol.L-1 homocysteine (Hcy), L-Cys or glutathione (GSH) with different interaction time was measured. The effect of pH on the enhanced fluorescence intensity of the NIR CdTe QDs (10 mg.L-1) at 5.0 mu mol.L-1 Hcy, L-Cys or GSH and the fluorescence responses of NIR CdTe QDs to 20 essential amino acids (5.0 mu mol.L-1 for L-Cys, 5.0 mmol.L-1 for the other 19 amino acids) in pH 7.0 PBS buffer was investigated. The probe offered good sensitivity and selectivity for detecting L-Cys, Hcy and GSH in the presence of 20 other amino acids, main relevant metal ions, and some other molecules in biological fluids. The recovery of spiked 5.0 mu mol.L-1 thiols in human serum and cell extracts ranged from 90% to 109%. The precision for 11 replicate measurements of the thiols at 5.0 mu mol.L-1 is in the range of 2.4%similar to 3.3%. The detection limits (3s) for L-Cys, Hcy and GSH are 43, 46 and 63 nmol.L-1, respectively. For real sample measurement, four serum samples and cell extract sample from two cancer cell lines (Hela and HepG2) were chosen and the analytical results were comparable with HPLC assay.

• 出版日期2014-1-15
• 单位天津医科大学