The Controllable Oxidation Reaction And Catalytic Properties Of Gold Nanoparticles

With the development of nanotechnology, functional nanomaterials such as silicon nanowires, carbon nanotubes and gold nanomaterials have extensively studied for applications in biochemistry and life science. Plasmonic nanoparticles show remarkable optical properties relating to localized surface plasmon resonance(LSPR), and show good photostability and biocompatibility, and are ideal optical probes for long-duration cell studies. However, there are still great challenges t o be addressed in future. For example, how to quickly and easily obtaining gold nanorod with specifically longitude plasmonic resonance wavelengths(LSPWs), and how to observe the chemical reaction process of nanoparticles in real time, when they can't be observe by common dark-field microscopy. T herefore, the main points of our work are summarized as follows:Chapter 2 provides two oxidants –ferric chloride and potassium dichromate for tailoring the longitudinal localize surface plasmon wavelengths(LSPWs) of gold nanorods(GNRs). T his two reaction processes yields GNRs with decreasing lengths but a fixed diameter, which correspond to the blue shift of LSPWs and the decreasing of aspect ratio. These two methods will result in GNRs with desired LSPWs, when using Fe Cl3 etching the GNRs, control the concentration of Fe Cl3 and CTAB or regulate the reaction time, LSPWs of GNRs will tailored precisely, and so as to the aspect ratio. When using potassium dichromate to tailoring the LSPWs, this process i s dependent on the p H and the concentration of potassium dichromate, when the reaction solution in neutral environment, the etching process would not happen, and the decreased of the p H lead to the increased etching rate. With this two methods, desired LSPW of GNRs could be obtained.In chapter 3, the oxidation process of gold nanorods were monitored at single particle level. Because of the sensitivity of CCD camera was different at different spectrum, and highly sensitive to spectral variation in some wavelength regions such as 540-590 nm. So in our work, the LSPWs of gold nanorods was tailored at about 650 nm firstly, and then with a home-built microscopy to monitored the continuously oxidation process. We have observed the changed color of single gold nanorod, and measured the chromatic value variations. And we expect this strategy to be widely used for the reaction process of other nanoparticles in real time.In chapter 4, a fluorescence assay for the highly sensitive and selective detection of ascorbic acid(AA) using a gold nanoparticle(Au NP)-based probe was proposed. Compared with tradition method use OPDA(o-phenylenediamine) for the detection of AA, this method amplifier the signal, under optimal conditions, a liner relationship between OPDA and AA in the range of 4.2 ?M-88 ? M, with a detection limit of 2 ?M.