| Summary: | 博士 === 國立成功大學 === 化學系碩博士班 === 101 === Around 70 % of nature is filled with metals. For the past few decades, scientists have devoted to the study noble metal nanomaterials, which are still continuing. In this thesis the structural evolution and sensing of gold nanoparticles; and biomedical studies for upconversion nanoparticles is reported. There are four chapters in this thesis, with the introduction in the first chapter emphasizing the importance. In the chapter 2, aqueous solution containing two additives, chloroauric acid (HAuCl4) and trisodium citrate (Na3C6H5O7), were irradiated by sunlight, without any supplemental stimulus such as electric power, to form high-yield Au decahedra. Those Au nanodecahedra were thermodynamically stable and exhibited high performance sensing for lead (Pb2+) ions.
In the chapter 3 and 4, we focus on the topic of converting Ag nanostructure to Au nanostructure with the galvanic replacement reaction. Based on the difference in the redox potentials between two metal species, the galvanic replacement reaction is known to create an irreversible hollow nanostructure in a wide range of shapes. In the context of galvanic replacement reaction, continuous etching lead to the collapse of the hollow structures because of the excess amount of oxidizing agent. In contrast, we demonstrate the growth of solid nanostructures from a hollow frame-like architecture in the course of a galvanic replacement reaction without any morphology destruction. We report the successful transformation of solid Ag to solid Au counterparts using straightforward chemical reactions. The successful conversion process relies on the decrease in reduction rate of the metallic precursor to initiate dissolution of Ag in the first stage (a galvanic replacement reaction), then a subsequent backfilling of Au into the hollowed-out structures. Here the reduction rate is controlled by the cetyltrimethylammonium bromide (CTAB) surfactant, as they interact with the metal salt precursor to form a complex species. To continuous the above concept inside a shell, we design inert silica coated Ag nanostructure (nanoprism), where the core replacement was studied with aqueous HAuCl¬4 addition at room temperature. We report the successful composition transformation of silica-coasted solid Ag to solid gold via Ag/Au alloy hollow structure without any morphology destruction.
With respect to the NIR-absorptive nanomaterials, we focus on the system of upconversion nanoparticle (UCNPs). It is noted that there has been no report on the systemic administration UCNPs-based drug delivery agents for evaluation of bioimaging and chemotherapy. We design the photocaged upconversion nanoparticles as the NIR-triggered targeting and drug delivery vehicles that successfully deliver for in vitro and in vivo for near-infrared light photocontrolled targeting, bioimaging, and chemotherapy via NIR irradiation. The caged UNCPs serve as a platform for the improvement of selectively targeting and possible reduction of adverse side effect from chemotherapy.
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