Synthesis And Application Of Chitosan Modificated ZnO Quantum Dots

Quantum dots (QDs) also known as semiconductor nanocrystals, have unique excellent characteristics, optics, electromagnetic and other special properties, in the field of life sciences and analytical science, which has been attracted much attention. Due to QDs pose an intense narrow fluorescence emission, a broad excitation spectrum, photostability and resistanting to photobleaching. It makes them suitable for fluorescent probe. Copper is one of the most necessary trace elements in organism. It plays an important role in physiological and biochemical functions. But the deficiency of the copper for a long time will cause physiological disease. As a result, the detection of trace copper is very important. In this article, chitosan (CS) modificated fluorescence ZnO quantum dot have been successfully synthesized as fluorescent probe for detection of Cu2+ are reported.Firstly, zinc acetate was used as a zinc source to preparate ZnO quantum dots in aqueous solution through hydrolysis synthesis method. And diethanolamine (DEA) was used as a stabilizer agent, oleic acid (OA) used as a dispersing agent. ZnO quantum dot with luminescent and water stability and good water dispersibility was fabricated. The as-prepared QDs were characterized by transmission electron microcopy (TEM), Particle size analyzer (PSA), infrared spectrum (IR), fluorescence spectrum (FL), respectively. The results indicated that the synthesized ZnO QDs had spherical structure, uniform size distribution and the average grain size of 100 nm. The effects of different conditions on the luminescence intensity of the ZnO QDs were investigated. Moreover, the growth mechanism of ZnO QDs was also explained.Secondly, chitosan modified ZnO quantum dots was synthetized with slight introduction of chitosan with biocompatible. The morphology, structure and optical properties were investigated by transmission electron microcopy (TEM), Particle size analyzer (PSA), infrared spectrum (IR) and fluorescence spectrum (FL). The results showed ZnO quantum dots modificated with chitosan could enhanced the photoluminescent, the stability in aqueous environment and biocompatibility of the QDs. Further, the reaction conditions were optimized And mechanism of modifiction was briefly discussed.Finally, highly photoluminescent chitosan modified ZnO quantum dots as fluorescent probe was developed for determination of Cu2+ base on the quenching of QDs fluorescence by copper(?). The effects of different conditions on the determination of Cu2+fluorescence intensity were investigated. At the optimum conditions, The quenched fluorescence intensity (?F=F0-F) was linear relationship with concentration of Cu2+ range from 0.4 to 20.0 ?mol/L. The linear regression equation was ?F=58.83 c+66.77 with a correlation coefficient of 0.9889, the detection limit for Cu2+ was 0.101 ?mol/L. And the mechanism of quenching was explained.