Study On Nanomaterials Fluorescence Chemosensor For Cyanide Anion

Chapter1:The concept and characteristics of nanomaterials were discussed in brief. The preparation methods, characterization techniques and applications in detecting ions were also reviewed in detail. And the main research contents were finally proposed based on the research background of gold nanoparticles.Chapter2:The soluble N-acetyl-L-cysteine protected gold nanoparticles were synthesized by using NaBH4as a reducing agent. The morphology, particle size and distribution were characterized by transmission electron microscopy (TEM), Ultraviolet absorption spectra (UV) and fluorescence. Sphere, evenly dispersed particles were observed from TEM images. No typical surface plasmon band in UV spectra indicates the particles size is smaller than2nm. And the broad excitation range with an emission spectra ranging from visible range to near IR was also investigated. The fluorescence intensities of NAc-AuNPs decreased gradually with increasing concentration of cyanide. So a rapid and simple method for the detection of cyanide was described based on the dissolved mechanism between gold and cyanide. Optimal experiments including pH (11) and reaction time (18minutes) were confirmed furtherly. Under the optimal conditions, a good linear range from1.0x10-7M to1.1xlO-6M and detection limit6.4x10-8M was obtained. All the other common anions could not quench the fluorescence of NAc-AuNPs under the same condition, so the sensor showed high selectivity and sensitivity towards CN-Chapter3:Different ratio (2:1,3:1,4:1,5:1,6:1) LsGFCs were prepared by chemical reduction of HAuCl4with lysozyme. Herein, time-dependent fluorescence spectra of4:1LsGFC were performed, which showed that the reaction process completed in8h. The obvious difference between the color of LsGFC aqueous and fluorescence under365nm was also observed.Chapter4:A method for detecting cyanide was developed based on the fluorescence quenching of LsGFC by cyanide. The selectivity of the cyanide sensor system was evaluated by color photograph and fluorescence spectra, respectively. Under the same condition, only ClO4-and SCN-could quench the fluorescence of LsGFC among thirteen kinds of anions, but the reponse of ClO4-and SCN-was less than that of cyanide. The quenching mechanism was based on the Elsner reaction between Au (0) and CN-in the presence of oxygen. A good linear relationship between5x10-6M-1.2x10-4M and detection limit1.9x10-7M was reached.Chapter5:This chapter summarized the main research findings in ratiometric fluorescence detection and speculated on the future research work.