Study On Application Of Fluorescent Gold Nanoclusters On Cobalt And Silver Ions Detection

Metal nanoclusters（M NCs）are a new type of fluorescent nanomaterials.Due to their unusual physical and chemical properties and good optical properties,such as long fluorescence lifetime,ultra-small size,large Stokes shift,fluorescence tunability and excellent biocompatibility and light stability have attracted more and more attention in the fields of biomarkers,biosensing,bioimaging and targeted cancer treatment.At present,many researches focus on synthesizing fluorescent nanoclusters with high fluorescence quantum yield（QY）and high selectivity and sensitivity in biosensing to expand their applications in various aspects.In this thesis,gold nanoclusters are mainly used as research objects.The synthesis,optical properties and applications of gold nanoclusters were studied and their applications on colbat and silver ions were realized.The specific research contents are as follows:1.A highly fluorescent green emission GSH-Au NCs was synthesized in this thesise,and the detection conditions of Au NCs for selective detection of metal Co²⁺were studied.It was found that at the pH of 6.0,low concentration of Co²⁺can selectively quench the fluorescence of GSH-Au NCs and there is a good linear relationship between the photoluminescence（PL）intensity of Au NCs and the concentration of Co²⁺in the concentration range from 2.0 to 50.0μM.The linear regression equation is I₀/I=0.1187C_Co²⁺+0.6085,the correlation coefficient R² is 0.9950,and the detection limit（3σ）is 0.12μM.Thus,a rapid,highly selective and visual fluorescence analysis of metal Co²⁺was realized.2.A yellow-green fluorescent methionine-gold nanoclusters（Met-Au NCs）was synthesized using methionine（Met）as a template at 37℃.It was found that addition of certain concentration of Ag⁺in the process of Met-Au NCs synthesis would tunne the PL peak of Met-Au NCs from 536 to 580 nm and induce a fluorescent color changes from yellow green to red.There is a linear relationship between the PL wavelength shifts and the Ag⁺concentration.Based on this phenomenon of fluorescence red-shift,a fluorescent nanoprobe can be established to achieve highly selective and visual fluorescence analysis detection of silver ions in the range from 18.0 to 210.0μM.3.A weak-fluorescence cystine stabilized Au NCs（Cys-Au NCs）was synthesized by one-step chemical reduction method using cysteine as a template.The weak-fluorescecne of the Cys-Au NCs could be enhanced rapidly and significantly and by addition of small amount of silver ions.The enhanced fluorescence color is yellow-green with the maximum excitation peak of fluorescence is at 378 nm and the maximum emission peak is at 535 nm.The method proposed here can not only prepare a nanomaterial with high fluorescence quantum yield,but also realize fast and visual fluorescence detection of silver ions in water.The results indicated that the method can achieve rapid visual analysis of silver ions in the concentration range of 3.0–20.0μM.