| 摘要: | 研究期間：10108~10207;Nanotechnology has tremendous promise and applicability in a variety of different sectors. However, there are also concerns that it can generate a new class of environmental hazards, i.e., nano-particles (NPs) are released to the environment, followed by exposure of either the ecosystem or human beings with resultant adverse health effects. Recently, the emerging discipline, nanotoxicology, has focused on correlating NP physicochemical properties with their toxic potential (Oberdörster et al., 2005; Jiang et al., 2008). To establish this relationship and ensure that results are reproducible and meaningful, synthesis of NP with well-controlled properties and accurate characterization of NPs are essential. Ag NPs have been extensively used in the commercial products, such as socks, paints, medical textile, food storage containers and home appliance, because of their antibacterial activity. In this study, several different common Ag NP generation methods, including evaporation-condensation method, spray pyrolysis method and wet chemical method, are selected and the corresponding Ag NP generation systems will be developed. The synthesized Ag NPs will be well-characterized using different analytical techniques. The particle mobility size distributions will be measured online using a scanning mobility particle spectrometry (SMPS). After particle collected on the filter, transmission electron microscopy (TEM) will be used to investigate their morphology and measure the primary particle size distribution. BET and Nano-particle surface area monitor (NSAM) will be used to measure the specific surface area of the NPs. The effective particle density will be determined by Aerosol Particle Mass Analyzer (APM). In addition, the aerosol particles in the real world are generally in the form of complex aggregate rather than simple sphere. The morphology of NP has been suspected to be an important parameter in terms of NP toxicity (Berube et al., 1999). However, the particle morphology control and characterization is always a challenge in aerosol science and technology. In this study, the fractal dimension (Df) will be used to characterize aggregates NPs and the system described by Kim et al. (2009) and Scheckman, McMurry and Pratsinis (2009) using a DMA and an APM in tandem will be applied to determine the value. A system containing a coagulation/ageing chamber in between two furnaces proposed previously will be used to vary the particle morphology. In addition to the conventional setup, the coagulation chamber will be further modified to include an external AC or DC electrical field. Ideally, the particle collision directions would be influenced by the external electrical field and thus change their morphology from a chain-like structure to spherical compact agglomerate. This modification is first proposed in this study and will be tested for Ag NP morphology control. In summary, currently there is still uncertainty in the understanding of the relationship between particle physico-chemical properties, such as size distribution, surface area, morphology, effective density, and potential toxicological effects. In this study, we would like to establish several different NP generation systems and well characterize these NPs for toxicity researches to clarify the issues. In addition, a nose-only exposure chamber will also be build for animal inhalation toxicity experiments. |
