Study On The Properties Of The Quantum Dots And Their Application In Analytical Chemistry

Under investigating the development of quantum dots,the synthsies and basic properties of PbSe and CdTe quantum dots have been studied,and made the quantum dots for the application in analytical chemistry.The content of this thesis are divided into four chapters and are listed as follow:Chapter one,the authors introduced the basic conception and physical property of the quantum dots,reviewed the recent progress about their synthesies and applications in bioanalytical chemistry,and analyzed the deficiency and localization,and then put forward the research aim of this thesis.Chapter two,a novel PbSe QDs modified glass carbon electrode,in which PbSe QDs was capped into Nafion(R)membrane on the surface of the electrode by drying method,was prepared and applied to investigate the electrochemical behaviors of clenbuterol(CLB).The electrode was characterized by UV and electrochemistry.The results indicated two oxidative peaks at 0.468V and 1.06V,one reductive peak at 0.252V in the Britton-Robinson(pH=2.81)buffer solution were observed,and the reductive peak current is proportional to the concentration of CLB over the range of 5.0×10^-7～2.4×10^-5 mol·L^-1,i_pc=0.1378C+0.2033(R=0.9970).The detection limit is calculated to be 6.27×10^-8mol·L^-1.The method is also applied to detect the content of CLB in pig meat.Chapter three,a water-soluble CdTe QDs was prepared using mercaptoacetic acid as stabilizer,and effects of pH and amino acids on fluorescence of CdTe QDs were investigated.The results revealed that the fluorescence of the CdTe QDs varied with the change of pH,and alanine and serine could quench the fluorescence while cysteine enhanced the fluorescence.Chapter four,the interaction of Cadion 2B with mercaptoacetic acid-stablized CdTe QDs in aqueous medium was studied by spectroscopy.The effect of pH,surfactant, medium and dosage of the Cadion2B were also investigated.The experimental results showed that Cadion 2B can react with CdTe QDs with a new absorption peak,and can quench the fluorescence of CdTe QDs in some extent,suggesting that CdTe QDs were coated by Cadion 2B,the coverage ratio of Cadion 2B on the surface of CdTe was estimated as 52%.Thermodynamic calculations revealed that the interaction is a spontaneous process in which electrostatic interactions play a major role,and the apparent equilibrium constant was calculated to be 1.483×10⁶ L·mol^-1.