Synthesis Of Gold Nanocluster And Silver Nanofiber And Its Application In Biomedicine

At present, nano-material gradually becomes the foundation of many subjects and research. Due to their small-size effect, surface effect and the quantum tunnel effect, nanomaterials have very wide applications in optics, electronics, magnetics and turned into hot spot in recent years. In particular, some novel metal nanomaterials such as gold nanorod, silver nanowire etc. have attracted strong researcher's far-ranging interests because they have strong effects in surface enhanced raman scattering(SERS), localized surface plasmon resonance(LSPR) etc, which can be used in chemistry-biology sensing, cell labeling and gene delivery and so on. This thesis studied the synthesis, characterization, and application of two gold and silver metal nanomaterials. The main works were summarized as follows:1. Synthesis of gold nanocluster and its application in cell imaging. Recently, there are increasing reports on the preparation and biological application of fluoesecent gold and silver nanoclusters. As a new fluorescent complex, gold nanocluster have many advantages compared to conventional organic dyes and quantum dots. For example, nanoclusters have no photobleaching and photoblinking, which allow researchers to observe sample for more time; they are small enough and do not disturb the interaction between proteins; they also have good biocompatibility and so on. Here, we synthesized dendron protected fluorescent gold nanocluster at room temperature( composed of several or tens of gold atoms, with high qutuman yield of 24.5%) which was successfully proved to have high selectivity on tumor cells..In this work, firstly, we synthesized G3.5-dendron which is no fluorescence, then conjugated folic acid to G3.5-dendron by covalent linking. At G3.5-dendron-folic acid's protection, gold nanocluster (GCDF) was produced successfully through reducing HAuCl4 by NaBH4. The gold cluster can be excited at 368 nm and its emission wavelength at 445 nm. In addition, it is also stable in PBS for long time. Compared with GCDF in water, the fluorescence intensity of GCDF in PBS and 10 hrs after didn not change. It has been proved that, relative to normal cell, folate receptor at tumor cell surface will overexpress. Incubated with tumor cell, GCDF can enter into the cytoplasm of tumor cell in short time, and produce strong fluorescence signal. GCDF can not recognize normal cell. These results demonstrated that the GCDF is highly specific and efficient for tumor cell recognition. 2. Silver nanofiber: synthesis and characterization. Based on the importance of nanomaterials, the synthesis and application of these nanomaterials is more crucial. Due to its special and anisotropic suface enhaced Raman scattering, field effect ect, it turned into hot spot in many subjects. Therefore, it looks significant to study its preparation methods. Herein, we used a facile method to prepare dispersed and soluble silver nanofibers in one step. This work differs from other methods mainly because we used a new polymer—PEOx. And we achieved to produce silver readily without addition metal ions. In our experiment, we studied amply different reaction temperature, reaction time, molar ratio, and injected sequence ect. to influence the shape and yield of silver nanomaterial. Finally, we optimized experimental conditions. Relative to some reported normal ways to synthesize silver nanofibers, our method is simple and high yield in a short time. At the same time, we presumed the growth mechanism of silver nanofiber reasonably according to experiment results. And how to apply the silver nanofiber, it will be very vital in our future work.