Fabrication Of Optical Sensing Platform Based On Cyclodextrins Functioned Mn-doped ZnS Quantum Dots

Quantum dots (QDs) are widely used in physics, chemistry and biology based on their excellent optical properties such as excellent photochemical stability, high luminous efficiency, continuous absorption spectrum, emission spectrum in accordance with the change of particle size. In recent years, as a kind of fluorescent material with high characteristic energy band-gap (3.65 eV), ZnS QDs has attracted extensive research interests because of its good optical properties and lower toxicity. In this paper, (3-CD modified Mn doped ZnS quantum dots with high luminous efficiency and high water-solublility were synthesized, and then a series of optical sensing platforms were fabricated. The main contents are as follows:Chapter 1:The basic concepts and properties of quantum dots were briefly introduced, and then the synthesis methods and their applications concerning quantum dots were briefly reviewed. Finally, the background, main research contents and the innovation points of this paper were described.Chapter 2:SH-β-CD Mn doped ZnS quantum dots (Mn-ZnS QDs) were synthesized using SH-β-CD as stabilizer, and then it was characterized by high resolution transmission electron microscopy (HRTEM), atomic force microscope (AFM), ultraviolet-visible absorption spectra (UV-vis), fluorescence spectrum and dynamic light scattering (DLS). Based on the fluorescence difference of Mn-ZnS QDs caused by tryptophan isomers, chiral recognition of D-and L-tryptophan enantiomers were sutdied, and the factors effect on the chiral recognition including standing time, pH were investigated in details. An optical sensing platform for tryptophan isomers was fabricated based on Mn-ZnS QDs and the chiral recognition of D-and L-tryptophan enantiomers were achieved. Finally, the chiral recognition mechanism was explored in-depth.Chapter 3:SH-β-CD Mn doped ZnS quantum dots can emit strong room temperature phosphorescence at 590 nm. The selective interaction between the sodium pyrophosphate and SH-β-CD Mn doped ZnS QDs were examined using phosphorescence spectrometry. On this basis, using the catalytic hydrolysis of sodium phosphate by alkaline phosphatase, an optical sensing platform for the activity of alkaline phosphatase was fabricated. And then experimental conditions including reaction time, temperature and pH were optimized. The determination of the activity of alkaline phosphatase was obtained at relatively low pH.Chapter 4:On the basis of the luminescence of the as-synthesized a-CD Mn doped ZnS quantum dots; the interaction between nitrophenol isomers and QDs was discussed using the steady-state fluorescence or phosphorescence spectroscopy. An optical sensing platform for p-nitrophenol was developed based on the selective inclusion interaction differences among α-cyclodextrin and o-nitrophenol, m-nitrophenol, p-nitrophenol, and the possible sensing mechanism was also investigated.