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A green method, using pulsed spark discharge (PSD) to synthesize colloidal gold, is studied in this thesis. PSD uses spark discharge to synthesize gold nanoparticles (AuNPs) in deionized water (DIW) and/or ethanol (EtOH). While gold nanoparticles have widespread applications in many fields, especially for the human body, in use them must overcome the influence of NaCl and pH value; therefore, this study adds NaCl into PSD-AuNPs to simulate the human body to study its stability. Furthermore, a variety of protectants are added in an attempt to determine the best protectant for AuNPs and improve biologically compatible potency. From the results of this study, adding the long-chain-polymer Carboxymethyl cellulose (CMC) or Polyvinyl pyrrolidone (PVP-k30) can prevent nanogold from aggregation and precipitation in NaCl or different pH value and maintain the characteristic of nanogold dispersion by raising the repulsive force between the particles. The results of this study can be a reference of nanogold applying in biomedical science.

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In recent years, extensive researches have been studied on metal nano-fluid, especially the silver nano-fluid which can be applied in diversified fields, including mechanics, electrical, biomedical, etc. Currently, there are many methods to prepare the silver nano-fluid. Apart from the traditional chemical method, the electrical discharge machining (EDM) system preparation method has been proven feasible. This study prepared the silver nano-fluid and investigated the relationship between its process parameters and product characteristics. Previous research has found that the silver nano-fluid prepared by EDM contained both silver nanoparticles and silver ions. To examine the relationship between the stability of silver nano-fluid and the process parameters, this study quantified the relationship of process parameters to the material removal rate (MRR) of silver electrode and silver ion output rate (IOR) in the fluid, with the attempt to achieve the most effective process parameter condition. In addition, the stability of silver nano-fluid was analyzed by various devices, including UV-Vis spectroscopy, sizedistribution and zeta potential analyzer. This study successfully quantified MRR and IOR under different process parameters, and drawn important conclusions on the suspensibility of silver nano-fluid prepared by EDM. The relationship between process parameters and suspensibility of silver nano-fluid obtained in this study can serve as references for future studies on the preparation of other metal nano-fluid by EDM process.

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