Studies On Functionalization Of Quantum Dots And Applications In Bioanalysis

Recently, the applications based on quantum dots in natural science and relative fields have attracted wide interest due to their unique optical, electronic, and mechanic properties. This thesis uses the functionalization of quantum dots as a theme, discussed the applications of functionalized quantum dots in bioanalysis. The content of this article are divided into four parts and described as follow:Chapter one, the basic characters, luminescence properties and preparation as well as applications in bioanalytical chemistry of quantum dots are summarized. Under predicting the development of quantum dots in the near future, the design of this thesis are put forward.Chapter two, the interaction between mercaptoacetic acid-stabilized CdTe QDs and quercetin and rutin in aqueous media were studied by spectroscopy. The effects of pH, reaction medium were examined. The results shown that quercetin and rutin could quench the fluorescence of CdTe QDs; The results of thermodynamic parameters demonstrated that the interaction were a spontaneous process in which electrostatic interactions play a major role. It also indicated that quercetin and rutin could be modified on the surface of quantum dots, and the coverage ratios were estimated as 41.19%,39.54% at room temperature respectively.Chapter three, water soluble CdSe QDs have been prepared facilely and functionalized with L-cysteine. The norfloxacin can quench the fluorescence signals of CdSe QDs in phosphate buffer solution. Based on this, a rapid, novel method for norfloxacin determination at 7.40 phosphate buffer solution was proposed. The effect of pH and reaction time were examined. Under optimum conditions, norfloxacin concentration, between 5.0×10-6 and 1.0×10-4mol/L, versus QDs fluorescence gave a linear response with an excellent 0.999 correlation coefficient, the limit of detection is 1.89×10-7 mol/L. And the quenching constant was also obtained, which was 2.47×104 L·mol-1. The proposed method was used to the analysis of capsule of norfloxacin, and a well result was received.Chapter four, the interaction between CdTe QDs and bovine serum albumin (BSA) was systematically investigated by spectroscopy under physiological conditions. The experimental results showed that the fluorescence of BSA could quench by CdTe QDs with a static quenching mechanism, indicating that CdTe QDs could react with BSA. The quenching constants according to the modified Stern-Volmer equation were obtained. Thermodynamic results showing that electrostatic interaction in the system played a major role. According to Forster theory, the distances between Trp-212-in BSA and CdTe QDs were given as 2.18 nm. The date of spectroscopy confirmed further that the conformations of BSA before and after interacting with CdTe QDs were changed.