Preparation And Biological Applications Of Noble Metal Nanoparticles

Since1980s, the scientists have realized that the properties of the materials will be greatly changed if the sizes are reduced in the range of mesoscopic scale. Many novel properties are beyond traditional theories when the materials are nanosized. Thus, they are of challenges. The noble metal nanomaterials have become one of the most active branches in nanotechnological area because of their distinct catalytic, electronic, magnetic, and luminescent properties. In this dissertation, we focus on the luminescent properties of gold nanoparticles and the photo thermal therapy on cancer using Ag/CuS nanocomposites.(1) Glutathione as a stabilizer and a soft reducer, were mixed with AuCI2as a1:1or5:4ratio to obtain red luminescent or near-infrared luminescent gold nanoclusters. UV-vis absorption, photoluminescence spectra, high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and so on, were used to characterize the gold nanoclusters. On one hand, results show that the size of gold nanoclusters is very small about2nm without the representative absorption of surface plasmon resonance around520nm. XPS analysis reveal the nature of luminescent gold nanoparticles with mixed valence states generated from dissociation of polymeric Au(I) thiolates. On the other hand, the potential application of gold nanoclusters in the X-ray luminescence and cell imaging were also explored.(2) The noble metal nanoparticles such as gold, silver and copper have the surface plasmon resonance to result In the bright colors. And heat will also be produced to kill cancer cells, which is called photothermal therapy. So far, the common photothermal agents are gold nanoparticles, carbon nanotube and copper sulfide nanoparticles. Cooper sulfide nanoparticles have attracted a lot of attentions from scientists due to simple preparation, low cost and easy modification. However, their photothermal transfer efficiency is not as good as gold nanoparticles. Thus, we try to use the local surface plasmon resonance (LSPR) of silver nanoparticles to enhance the absorption of copper sulfide nanoparticles in the near-infrared region. The results show that the absorbance of CuS nanoparticles in Ag/CuS nanocomposites is enhanced about4times by Ag nanoparticle surface plasmon coupling. The corresponding photothermal transfer efficiency is also enhanced by the temperature measurement in the solution. Using the luminescent properties of Ag/CuS nanocomposites, the time course cell uptake is also carried out. Ag/CuS nanocomposites can get into PC-3cells and are mainly located in their cytoplasm. After4hours incubation, the cell uptake is saturated and the luminescence reaches the brightest. Finally, a power per area of0.6W/cm2with a980nm laser is sufficient to kill cancer cells for Ag/CuS nanocomposite-PTT activation in vitro observations, which is in the range of the conservative limit of980nm laser intensity (0.726W/cm2). In summary, Ag/CuS nanocomposites are a new and promising modality for cancer treatment.