| 摘要: | 隨著奈米科技蓬勃的發展，奈米產品也不斷地推陳出新。但奈米產品對人體或生態環境所造成 的潛在危害，至今仍未完全釐清。因此，如何對奈米級微粒進行毒性測試及評估成為近年來重要的環 境議題。目前，由於體外細胞株試驗具有實驗成本較低與可針對特定細胞做直接的測試等優勢，且避 免動物實驗引起的倫理問題，故被廣泛使用。而氣液介面(air-liquid interface, ALI)暴露系統更被認為是 較能反映真實呼吸暴露微粒情境的實驗系統方法。然而其對於奈米微粒的收集效率偏低，將影響暴露 實驗的準確性和適用性。因此，本研究提出開發和評估用於奈米微粒的靜電集塵式氣液介面細胞暴露 系統(ESP-ALI)。ESP-ALI 的收集效率主要受到微粒的帶電狀態影響，本研究試圖以電噴霧方法增加微 粒的充電效率。電噴霧通常用於產生單分散奈米微粒，但電噴霧產生的液滴為高度帶電，亦可取代電 暈放電成為充電過程的離子源。而且電噴霧方法不會產生任何臭氧，因此本研究所設計由電噴霧充電 輔助的ESP-ALI 系統，可以避免傳統ESP-ALI 系統中臭氧對於細胞暴露實驗的潛在干擾。此外，微 粒形態可能影響ESP-ALI 收集效率以及細胞毒性，故在本研究將利用不同形態的微粒(包括球形的蔗 糖微粒，非球形的奈米煙塵微粒和奈米銀微粒)測試ESP-ALI 的微粒收集效能。此外，為量化微粒的 形態，將使用DMA 和氣溶膠微粒質量分析儀（APM，Kanomax 3601）的串聯系統量測所測試奈米微 粒/奈米聚集物體的碎形維度。 ;Nanotechnology has tremendous promise and applicability in a variety of different sectors. However, there are also concerns about the potential adverse effects on human body when exposed to these engineering nano-particles. Therefore, how to evaluate the potential toxicity of these nano-particles becomes a serious issue in recent years. Currently, three methodologies, including animal experiments, ex vivo studies and in vitro systems of exposure, are generally used to study adverse cellular effects induced by inhalable engineering nano-particles. Among these methodologies, in vitro experimental setups are widely employed due to its relatively low labor and capital cost. In addition, the in vitro studies can avoid the ethic issues provoked by animal experiments. Therefore, we proposed to develop and evaluate an ESP type air-liquid interface (ALI) exposure system for nano-particle and nano-aggregate cell exposure experiments. Since the performance of the ESP type ALI system strongly depends on the particle charging status. In this proposal, we would like to increase the particle charging efficiency using the electrospray method. The electrospray is generally used for generating monodisperse nano-particles. The droplets produced by electrospray are highly charged and the process would not generate any ozone, which is the byproduct of corona charging. Ozone is recognized as the toxic gas for cell, and thus the proposed ESP-ALI system assisted by the electrospray charging could eliminate the potential interference of ozone for the cell exposure experiments. In addition, aerosols are not always perfectly spherical. More importantly, the particle morphology can affect the ESP-ALI collection efficiency as well as the cell toxicity. In this study, particles with different morphology including spherical sucrose particles, non-spherical nano-soot particles and silver nano-particles will be used to test the performance of ESP-ALI for collecting nano-particles/nano-aggregates. Monodisperse nano-particles with different sizes will be selected by a Differential Mobility Analyzer (DMA, TSI 3081), and negative collecting voltages were applied step-wise on the prototype ESP-ALI system. Particle size distribution upstream and downstream of the system will be measured by a Scanning Mobility Particle Sizer (SMPS, TSI 3936), and the collection efficiency will be evaluated accordingly. Furthermore, to quantify particles morphology, the fractal dimensions of testing nano-particles/ nano-aggregates will be characterized using a tandem system of DMA and Aerosol Particle Mass Analyzer (APM, Kanomax 3601). |
