The Application Of Fluorescent Silver Nanoclusters In Biomolecule Detection

Ultrasmall metal nanomaterials, which are typically consisted of several to a few hundreds of metal atoms, are known as metal nanoclusters (NCs). NCs have many unique molecules-like and nanoparticle-like properties. Fluorescent nanoclusters have high resistance to photobleaching, which makes it an alternate to organic fluorescent dyes.With the development of molecule biology, it is very important to accurately detect and control biological molecules. Fluorescent silver nanoclusters have unique optical properties, tiny sizes and good biocompatibility. These properties make it have wide perspective applications in molecule biology, especially in biomolecule detection.In this thesis, various silver nanoclusters (Ag NCs), which are stabilized by different thiol ligands, were synthesized. The fluorescent silver nanoclusters were placed in various chemical environments. The fluorescence emission mechanism was explored, and found out that fluorescence channel of N-Ag at 420 nm and Ag-carboxyl between 550 nm-650 nm. We proposed that the luminous mechanism is not only related to the quantum confinement effect, but also to proper ligand. In this thesis, we find that the fluorescence emission from the silver nanoclusters (Ag NCs) with thiol is based on fluorescence channel induced by the interaction between N atoms or carboxyl group and the Ag nucleus of clusters. It is different from the point that emission fluorescence is based on fluorescence channel induced by the interaction between S atoms and the Ag nucleus of clusters.At the same time, a new type of fluorescent silver nanoclusters probe was synthesized and successfully used in the detection of glutathione (GSH). It is different from the traditional fluorescent probes which work only depending on fluorescence quenching/enhancement effect. In this thesis, the fluorescence probe is based on quenching and shifting of fluorescence peak, so the probe has higher precision and selectivity. What’s more, the detection results can be achieved rapidly. This new type of fluorescent silver nanoclusters probe is expected to achieve intracellular detection after further development.In this thesis, the detection mechanism of the probe was also explored. By comparing with the GSH-like molecule, we found that interaction between the probe and the biological molecule. At the same time, a new fluorescence channel is formed, which leads to the blue shift of the fluorescence peak position of the probe, and the fluorescence intensity also decreases. Biological molecule GSH with sulfhydryl groups is able to etch and complex Ag nucleus, resulting in the N atoms, and carboxyl approaching Ag nuclear and complexing with Ag nuclear. Etching effect leads to fluorescence quenching, and the complexation of N with Ag leads to the change of fluorescence peak position. The change of fluorescence peak and intensity can meet the specific relationship, so that the fluorescent nanoclusters can accurately detect GSH. This thesis provides a new path to develop fluorescent probes.