Preparation Of Water-soluble Quantum Dots And Their Detection Of Copper Ions

Quantum dots,also known as semiconductor nanocrystals,are a class of nanomaterials with excellent fluorescence properties.Compared with the traditional organic fluorescent dyes,quantum dots have the advantages of wide excitation spectrum,narrow emission spectrum and good photochemical stability.Therefore,they are widely used in environmental monitoring,disease diagnosis,detection of heavy metal ions,fluorescence analysis and cell imaging prospect.In this paper,different mercapto compounds were used as stabilizers to synthesize CdTe QDs in aqueous phase.In order to select better thiol complexes,.the morphology,composition,crystal structure and fluorescence intensity of CdTe QDs were investigated.The experimental conditions such as the pH of the reaction system,the reflux time,the reaction temperature and the reactant ratio were optimized,the optimal experimental conditions were as follows:nCd:nTe:nMPA =1:2:2.4,pH =9.0,T = 100? and reflux time is 2.0 h.The synthesized CdTe QDs were treated with organic amine reagent and inorganic metal ions to improve the fluorescence intensity of QDs.Secondly,with mercaptopropionic acid as stabilizer,CdTe:Zn quantum dots with good photostability,high fluorescence intensity and high quantum yield were synthesized in high pressure reactor.The quantum dots doped with Zn modified the surface defects of the single-core CdTe QDs to a certain degree,which improved the light stability,quantum yield and fluorescence intensity and reduced the QDs toxicity.The optical properties of CdTe:Zn were investigated by characterizing its morphology,composition,crystal structure and fluorescence intensity.By utilizing the quenching effect of copper ions on the fluorescence of the quantum dots,which the optimized water-soluble CdTe:Zn quantum dots as the fluorescent probe,the qualitative detection and quantitative analysis of copper ions in water are successfully achieved.The experimental results show that there is a linear correlation between FO/F and CCu2+ in the Cu2+ concentration range of 3-21 ?mol/L,the linear regression equation is FO/F = 0.09588 C + 0.7964(C is the concentration of Cu2+,the unit is?mol/L),the linear correlation coefficient R2 = 0.968,the detection limit 0.8135?mol/L The fluorescent probe is expected to be practically used.