Study On The Preparation Of Copper And Silver Nanoclusters And Its Applications In Detection

Metal nanoclusters refer to a relatively stable aggregates composed of a few to several hundred atoms under the protection of certain molecular layer. Its unique quantum size effect makes its optical properties related to its size and this feature makes its fluorescence emission spectra tunable in the visible and near-infrared area. In addition, its good biocompatibility, strong stability, good aggregation ability and larger stoke displacement significantly improved the sensitivity of existing analytical method. As a result, the metal nanoclusters are widely used in environmental detection, biological detection, biomarkers, biocatalysis and other fields.We focus on metal nanoclusters and discuss the special optical properties of copper and silver nanoclusters in this paper. In addition, we applied the copper and silver nanoclusters into biochemical analysis and established a series of analysis methods based on the local surface plasmon resonance scattering and fluorescence techniques. Our main research content is as follows:1. We employed3-aminopropyltriethoxysilane (APTES) to assist the one-step synthesis of Ag NCs using polyethyleneimine(PEI) as the template and characterized the prepared silver nanoclusters using TEM technique, UV-Vis spectra, FT-IR spectra and so on. We also explored the influence of the Hg2+on the as-prepared silver nanoclusters using the resonance light scattering technique, and we find that its detecting concentration range is0.1-7000nM. Meanwhile, satisfactory results were obtained in real sample analysis due to its good selectivity and sensitivity. Furthermore, through contrasting the TEM, UV-Vis and FT-IR spectra of the silver nanoclusters in the presence and absence of Hg2+, we find that it is the strong interaction between Hg2+and PEI that lead to the aggregation of PEI-Ag NCs and finally enhances the resonance light of the NCs.2. By controlling the reaction time and molar ratio of Ag and glutathione, we synthesized the Ag nanoclusters with tunable emission intensity at430nm and630nm using electrostatic induced reversible phase transfer method. The effective dual-emission fluorescent Ag nanoclusters were characterized using TEM technique, UV-Vis spectra, FT-IR spectra and so on. We obtained a wide detection range, good selectivity and sensitivity in the detection of Cys based on the tunable fluorescence emission property of the GSH-Ag NCs. The experimental application result showed that the Ag nanoclusters have good environmental suitability as a fluorescence probe and it can avoid the interference of other amion acids existed in urine with an accurate detection of Cys. Furthermore, through contrasting the TEM, UV-Vis and FT-IR spectra of the silver nanoclusters in the presence and absence of Cys, we find that it is the interaction between Cys and Ag that lead to the aggregation of GSH-Ag NCs and finally quenched the fluorescence of the NCs.3. We prepared an efficient fluorescence BSA-Cu NCs, and characterized it using TEM technique, UV-Vis spectra, FT-IR spectra and so on. The result showed that the modified function of BSA was achieved through the interaction of-SH and Cu2+. We explored the influence of Cu2+on the fluorescence of copper nanoclusters and got the detection range of0-35μM based on the fluorescence properties of Cu NCs. Benefiting from the strong binding ability between EDTA and metal ions, the BSA-Cu NCs were exploited as a "turn-off" sensor for Cu2+ions and a "turn-on" sensor for EDTA which makes the Cu NCs promising on the application of detecting Cu2+many times.