| 摘要: | 近年來奈米(Nano) 這個名詞不斷的出現在我們的日常生活中。政府與產業界也將奈米科技(Nanotechnology)視為明星產業，期望能為我們創造更便利的生活，帶來更多的就業機會。但是，隨著奈米科技的發展，大家也漸漸注意到奈米科技在帶來便利的同時也有可能產生新的環境危害。例如：在奈米科技中所使用人工製造的奈米微粒(Nanoparticle, NP)，在使用或是製造過程中將不可避免的被釋放到環境與生態系統之中。而這些奈米微粒對於人類及其他環境中的生物都可能會產生不良的健康影響。因此，這幾年奈米毒理學成為一項熱門的新興學科。許多學者致力於研究奈米微粒的各項性質與其毒性的相關性(Oberdörster 等人，2005 年；Jiang等人，2008年)。而要研究這些關係並確保其實驗結果的再現性，建立可精準控制的奈米微粒產生系統與準確表徵其各項的物化性質極為重要。銀的奈米微粒因為其良好的抗菌活性，所以已經被廣泛的使用在襪子、塗料、醫療織品、食品存儲容器甚至家電等商業產品之中。但是，有些學者也提出銀奈米微粒的抗菌機制可能也會對人體細胞產生毒性。在這項子計畫研究中，我們將建立幾種不同銀奈米微粒的產生系統利用不同的產生機制，包括evaporation-condensation method, spray pyrolysis method 和wet chemical method。所製造收集的銀奈米微粒將供給本整合型計劃其他研究人員作為毒性等實驗之用。而且，此子計畫將利用不同的儀器技術來量測分析所產生的銀奈米微粒的各項性質。Scanning Mobility Particle Spectrometry (SMPS)將會用來量測所產生銀奈米微粒的粒徑分佈。Transmission Electron Microscopy (TEM) 將會用來觀察銀奈米微粒的膠結構形與主要組成微粒的粒徑。BET 和Nano-particle surface area monitor (NSAM)將會用來定量分析銀奈米微粒的表面積。Aerosol Particle Mass Analyzer (APM) 將會用來量測銀奈米微粒的有效密度。此外，在環境中採集到的氣懸微粒通常發現是以膠結(aggregates)的複雜結構存在，而不是單純的單一球體。而奈米微粒的毒性已被懷疑的和其構形有關(Berube 等人, 1999年)。但是，如何精準的控制並具有代表性的描述微粒膠結的構形以供毒性研究在氣膠科學和技術上至今仍是一項相當具挑戰性的研究課題。在此研究計畫中，我們將用碎形裡的fractal dimension (Df)來表徵微粒膠結的構形。並建立與Kim等人（2009 年） 和 Scheckman，McMurry and Pratsinis （2009 年）相似的膠結微粒產生系統。此產生系統是利用調整氣懸微粒在一coagulation/ageing chamber裏的停留時間和其後端高溫爐的溫度以達到控制氣懸微粒膠結的形態。在本子計畫中，我們將更進一步改進此膠結微粒產生系統。計畫在coagulation/ageing chamber外部增加一交流或直流電場。理想的情況是，氣懸微粒的碰撞方向將會受外部的電場的影響，進而更改其膠結的形態。此項實驗設計是第一次由本子計畫所提出的，並將用於控制銀奈米微粒的構形。期望此新提出的膠結微粒產生系統可改變產生微粒膠結的形態從鏈狀結構(Df=1)到緊湊的球形團聚(Df=3)。總結，目前我們對於各項奈米微粒的物理-化學屬性與其潛在毒性之間的關係尚未完全理解。在本子計畫研究中，我們希望建立幾個不同的銀奈米微粒產生系統，並定量量測分析所產生銀奈米微粒的粒徑分佈、表面積分布、膠結構形和有效密度等性質。所產生的銀奈米微粒將收集後或直接提供給此整合型計劃中其他研究人員作為毒性等實驗之用。綜合整合型計劃中各方實驗成果與本子計畫之各項奈米微粒的性質量測，我們將可釐清與更進一步了解奈米微粒的物理-化學屬性與其潛在毒性之間的關係。此外，在本子計畫亦將設計製造一nose-only exposure chamber以用於動物吸入毒性試驗。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 表 C011 共 2 頁 第 2 頁 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. 研究期間：10008 ~ 10107 |
