Water-soluble Synthesis And Surface Molecular Imprinting Characterization Of Low Toxic Quantum Dots

Quantum dots (QDs) exhibit unique optical properties，which makes quantumdots broad applications. Beacause heavy metal ions, such as lead and cadmium,have toxicity, the synthesis and applications of low toxicity quantum dots have alsobeen paid more attention. Combining the selectivity of the molecularly imprintedpolymers and the optical properties of the quantum dots, composite materials withhigh sensitivity and high selectivity can be developed and used in the separation anddetection of complex sample. This paper discusses the synthesis and application oflow toxic and water-soluble quantum dots and molecular imprinted polymerfunctionalized quantum dots. The full paper includes four chapters, the main contentis introduced as follows:In chapter one, the basic conception, the methods of preparation, and the mainapplications of quantum dots and molecular imprinting technique, and the basicactuality of molecular imprinted polymer functionalized quantum dots were reviewed.Then put forward a preparativeplan for this paper.In chapater two, water-soluble functionalized Ag2S quantum dots were synthesiz-ed in ethylene glycol with3-mercaptopropionic acid as the stabilizer. Based on thecolor change and fluorescence quenching of Ag2S quantum dots, a highly sensitiveand selective method for the detection of trace mercury ions in water has beendeveloped. The characteristics of the quantum dots were studied by fluorescencespectra, scan tunneling microscope, X-ray diffraction, infrared spectrum and thermalgravimetric analysis. Under the optimum condition, the calibration graph about thequenched fluorescence of Ag2S quantum dots was linear in the range from8.0×10-9to5.6×10-8mol/L of the mercury ions concentration with a detection limit of4.2×10-9mol/L, and could identify9×10-5mol/L of mercury ions using the naked-eye method.The proposal has been successfully used for the determination of ultra trace mercuryions in water sample.In chapter three, molecular imprinted polymers (MIP) appended onto silicacapped Mn-doped ZnS quantum dots (ZnS:Mn@SiO2@MIP), were prepared using bisphenol A (BPA) as template molecular,3-aminopropyltriethoxysilane (APTES) asfunctional monomers, tetraethoxysilane (TEOS) as cross linker, compared to non-molecular imprinted polymers (ZnS:Mn@SiO2@NIP). The results showed that theas-prepared ZnS:Mn@SiO2@MIP possessed good selectivity to template molecularBPA.In chapter four, water-soluble AgInS2quantum dots (AIS) have been synthesizedfor the first time in the presence of dBSA as capping ligand. Cytosine imprintedpolymers were obtained by radical precipitation polymerization in aqueous phase,using ethylendimethacrylate (EGDMA) as cross-linker and methacrylic acid (MAA)as functional monomers. The AgInS2quantum dots were connected with MIPs bycoupling agent. The results showed that the AgInS2@MIP possessed good selectivityto template molecular cytosine.