The Research Of Fluorescence Sensing Analysis Based On CdTe Quantum Dots

Compared with conventional organic fluorescent dyes, Quantum dots have many unique optical properties such as narrower emission spectrum and tunable emission wavelength, border excitation spectrum,high luminescent quantum yields and good photostability and so on.Owing to these superior properties,Quantum dots have been became an excellent fluorescent nanoparticles, and shows great prospects for development in chemistry, biology, medicine and other fields. Although the research of quantum dots as fluorescent probes has relatively mature, there are still many unsolved problems,such as to improve the performance of detection methods via the surfactant functionalization Quantum dots and so on.In this paper,as fluorescent probe,the water-souble CdTe QDs were modified by thioglycollic acid (TGA),a novel method was established for detecting flavonoid, Hg2+/Ag+and SudanⅠbased on the surfactant functionalization Quantum dots.The main research content is as follows:（1）Determination of flavonoid in buckwheat tea based on water-soluble CdTe QDs. CdTe QDs were modified by thioglycollic acid (TGA) synthesized in aqueous solution,and characterized by Ultraviolet-Visible absorption spectra and fluorescence emission spectrum,a novel method was established for detecting flavonoid based on the quencehing of fluorescence of CdTe. In the optimal experimental conditions，there was a linear relationship between the relative fluorescence intensity(F0/Fi) and the concentration in the range of2×10-6～3.6×10-5mol/L,and the limit of detection was1.54×10-6mol/L.The method was used to the detection of flavonoid in buckwheat,and the results were in line with UV spectrophotometry.In order to speculating the quenching mechanism,this paper also compared the different structure of flavonoid impact on the fluorescence intensity of QDs.Compared with other methods,this mothod has some advantanges such as simple,fast,low cost,and high sensitivity.(2) Determination of Hg2+/Ag+in water based on CdTe-CTAB system.We discovered that CTAB could increase the fluorescence intensity of CdTe in a certain concentration range.We speculated that the negative charge of the CdTe QDs modified by TGA,combined with a positive charge of CTAB by electrostatic interaction,which reduced the QDs energy loss caused by nonradiative transition. A novel method was established for detecting Hg2+/Ag+based on the quencehing of fluorescence of CdTe-CTAB. In the optimal experimental conditions, there was a linear relationship between the relative fluorescence intensity(F0/Fi) and the concentration in the range of10-8～8×10-7mol/L,and the limit of detection was9.67×10-9mol/L; There was a linear relationship between the relative fluorescence intensity(F0-Fi) and the concentration in the range of3×10-8～9×10-7mol/L,and the limit of detection was2.02×10-10mol/L. To detect Hg2+and Ag+, the selectivity is higher than CdTe.(3) Determination of SudanⅠ in chilli sauce based on CdTe-SDBS system. We discovered that SDBS could increase the fluorescence intensity of CdTe,a novel method was established for detecting SudanⅠbased on the quencehing of fluorescence of CdTe-SDBS. In the optimal experimental conditions,SudanⅠ could be determined at concentration range of8×10-7～2×10-5mol/L with the limit of detection was2.69×10-8mol/L. CdTe-SDBS system had higher sensitivity and wider linear range than CdTe QDs in the experiment.