Synthesis And Sensing Investigation Of Gold/Copper Nanoclusters

In recent years,the metal nanocluster(MNCs)as a new type of nano-materials possess excellent properties such as good water solubility,low toxicity,strong stability and high luminous efficiency,so it is widely used for detecting ions and biomolecules,biomarkers and imaging and so on.In this thesis,two kinds of biological molecules as ligands were used for synthesis of various metal nanocluster,for example,gold nanoclusters(AuNCs),copper nanoclusters(CuNCs)and bimetallic gold-copper alloy nanoclusters(AuCuNCs).And based on the changes of fluorescence intensity(quenching/enhance),several detection methods for the detection of ions and pH response were developed.At the same time,the detective mechanism of nanoclusters were researched.The main research contents are as follows:Chapter 1:We summarized the research progress on synthesis,properties and applications of MNCs.And we proposed the related research content on this basis.Chapter 2:L-amino acid oxidase(LAAOx)capped gold nanoclusters(LAAOx@AuNCs)were prepared by "one-pot" method in aqueous solution.And the water-soluble,red fluorescent AuNCs could be used as a novel and environmentally friendly fluorescent probe for detecting CN-(pH=11.0)and Hg2+(pH=7.0)under the optimal experiment conditions,respectively.In the presence of CN-(or Hg2+)the fluorescence of LAAOx@AuNCs could be quenched dramatically.And the quenching mechanism was studied in detail.In addition,our proposed methods were successfully applied to the determination of CN-and Hg2+ in the actual water samples or environment.Chapter 3:A simple,green and one-step synthesis approach in aqueous solution was reported for the preparation of the inexpensive chicken egg white(CEW)protected copper nanoclusters(CEW@CuNCs).It was developed without using any additional reducing agents and the product exhibited extremely stable properties.The fluorescent CEW@CuNCs for reversible pH sensors has been designed based on the distinctly fluorescence enhancing of CuNCs.Meanwhile,the fluorescence intensity of the CuNCs showed a linear relation over the pH ranges of 6.14-12.08 and increased by around 5-fold approximately at high pH values compare with a low pH of 6.14.In addition,the pH sensor was also sensitive to the different buffer solutions and the ionic strength had only a slight influence on the pH-responsive behavior.Chapter 4:In this study,water soluble bimetallic alloying gold-copper nanoclusters(CEW@AuCuNCs)have been synthesized through a facile "one-pot" synthesis route at a vital molar ratio of Au/Cu precursors in the inexpensive chicken egg white(CEW)matrix.The prepared AuCuNCs display red fluorescence and dual emission with peaks at 474 and 623 nm under excitation at 380 nm,respectively.Interestingly,in a different way to the usual quenching effects of other metal ions on the fluorescence of AuCuNCs,Ag+exhibited an enhancement effect on the photoluminescence of AuCuNCs at 590 nm.A ratiometric fluorescence method has thereby been established using AuCuNCs as fluorescent probes toward the detection of Ag+ ions with high selectivity and sensitivity.Under optimum conditions,the fluorescence intensity ratio(F590/F474)of the nanosensor against the concentration of Ag+ ions shows a good linear range from 0.5 to 30?M with a detection limit of 0.31?M.Furthermore,we demonstrate that the proposed AuCuNCs-based fluorescent assay can be applied to the determination of silver ions in real water samples.Chapter 5:We summarized the research results on metal nanoclusters(MNCs)as a fluorescence probe for applications in various ion and pH sensing aspects.Moreover,the future research was predicted.