Synthesis, Property And Application Of Functional Silver Nanoclusters

Silver nanoclusters have excellent optical properties and high sensitivity to heavy metal, which make them to be widly used in bio-imaging, bio-medicine and heavy metals probing. However, there are still many problems and challenges showed as follows:fast, high yield synthesis of monolayer-protected silver nanoclusters with well difined composition and structure; the effective characterization methods; the toxicity of silver nanoclusters in biological applications, etc.This dissertation contribute to the synthesis of silver nanoclusters, the research in cell-imaging and toxicity, the sensing of Hg2+in environmental samples, the toxicity prediction of silver nanoparticle by electrochemical methods (DPV), the toxicity mechanism of silver nanoparticles. In this dissertation there are five chapters:Chapter 1:Reviewof monolayer-protected nobel metal nanoclusters.This chapter gives an overview to the synthesis, characterization, and bio-applicaton of noble nanoclustersChapter 2:The One-pot one cluster synthesis, cell-imaging application and toxicity of a novel silver nanoclusters -Ag14(SG)11.A novel silver nanocluster Ag14 was synthesized by a one-pot one-cluster fashion after subtly tuning the reaction kinetics and thermodynamics. The yield of product (>96%) is the highest one achieved for the synthesis of metal nanoclusters so far to the best of our knowledge. The nanocluster composition was determined by isotope-resolved ESI-MS combined with other analyses, and the structure was probed by NMR.The fluorescence properties of Ag14 were investigated, and Ag14 was successfully applied to lung cancer (A549) imaging, representing for the first time to image cells labeled with small-molecule-protected silver nanoclusters. The toxicity of Ag14 has also been studied.Chapter 3:Probe toxicity of silver nanoparticles by DPV.It was first proposed in this work that DPV can be employed to preliminarily evaluate the toxicity of nanoparticles ions, based on the relationship between redox peak intensity of silver nanoparticles and toxicity. Although this electrochemical method can not completely replace the conventional biological measurement, it shows many merits compared with the MTT of this DPV assay:consumed in a short time, simple operation, cheap, which makes it a good method of predicting the toxicity of nanoparticles. In addition, the toxivity of silver is size-dependt, in the range of our study, the smaller size the lower toxicity. This also gives supporting that the silver nanoclusters is better choice in biological applications.Chapter 4:Fast, high-yield synthesis of new silver nanoclusters-Ag30 (Capt)18, and the sensing of Hg2+ in environmental samples.We have succeeded in fast (30 minutes), high-yield (74%) synthesis of Ag30(Capt)18. The composition was precisely determined by ESI-MS, and the structure was probed by 1D and 2D NMR. One interesting finding is that the clusters after protonation can dissolve in water and a large range of organic solvents with various polarity such as ethanol, acetone, acetonitrile, dichloromethane and ethyl acetate. Such a property imparts Ag30(Capt)18 a great merit for potential application. For the first time, a LTM method was developed to mask the interference from other cations and successed in sensing Hg2+ in the environmental samples.Chapter 5:Conclusion and outlook.Based on our previous work, we provide a conclusion and outlook.We make improvemet in the synthesis of silver nanocluster, and provide a favorable exploration of the silver clusters for future applications for these silver nanoparticles.