Preparation Of CdTe/CdS Core-shell Quantum Dots And Its Application In The Biological Analysis

Semiconductor quantum dots (QDs) are considered to have a potential for thechemical sensing due to their environmentally sensitive optical properties and highsurface to volume ratio. Compared with conventional dye molecules, semiconductorQDs has a lot of advantages, such as broad excitation spectra and narrow, tunable,symmetric emission wavelengths. In recent years, direct synthesis of QDs in aqueousphase is an alternative strategy to obtain water-soluble QDs, and the synthesis is morereproducible, less expensive and higher repeatability.It’s very important to detect biological substance for the early diagnosis anddisease treatment. Nitric oxide (NO) is a critical regulator in a variety of biologicalprocesses, such as cardiovascular relaxation, nervous transmission, and immuno-logical responses. Defects in NO pathway will cause lots of pathophysiological states,including hypertension, cardiac failure, diabetes mellitus, stroke, central nervoussystem (CNS) disorder and many others. It’s very important to control the glucoselevels in biological system because glucose has a great influence on human health.The glucose oxidase (GOD) method is a superior method that is widely applied in thedetection of glucose. These traditional methods are usually based on the electrontransfer mechanism of enzyme catalysis to detect glucose by the optical andelectrochemical methods. However, high sensitivity probes that can directly detect theglucose have not been found and the GOD enzyme activity has not been muchimproved. Rescent years, nanomaterials provide new fields for biological analysis anddetection when used as fluorescent probes. Water-soluble quantum dots can beapplied to the NO and glucose concentration detection, which shows severaladvantages such as real-time online detection, high sensitivity and low cost,This thesis was financial supported from the National Natural ScienceFoundation of China (NO.50802069) and the Fundamental Research Funds for theCentral Universities (WUT:2013-IV-010). We synthesized new water-solubleCdTe/CdS quantum dots and applied to the detection of nitric oxide and glucose,respectively. The main contents include: (1) One-pot synthesis of CdTe/CdS core-shell quantum dots has been used. Thesynthesis conditions are studied and the CdTe/CdS core-shell quantum dots havegood fluorescence properties.(2) CdTe/CdS core-shell quantum dots are used to detect NO gas and solutionconcentrations, respectively. The reaction mechanism between CdTe/CdS QDs andNO has been studied and the standard curves have been obtained.CdTe/CdS QDs offered good linear dynamic and reproducibility in NOconcentration between1×10-7mol/L~1×10-6mol/L and1*10-6mol/L~1*10-4mol/L,and the standard curves areI0/I=1+36095.8[NO] andI0/I=1+3239.4[NO],respectively.(3) Using CdTe/CdS QDs as carriers in the preparation of CdTe/CdS-GOD,which greatly improved the thermal stability and preserve stability of the immobilizedenzyme. The CdTe/CdS-GOD detection range of glucose concentrations is between1.0mmol/L~6.0mmol/L, which can be well applied in the detection of bloodglucose.