靜電集塵式ALI暴露系統之設計、開發與評估

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，如何對奈米級物體 (nano-object) 進行毒性測試及評估亦為現今奈米科技發展的重點之一。由於可避免動物實驗的道德爭議、實驗成本較低與可針對特定細胞做直接的測試等優勢，故使用浸沉培養方法的體外細胞株試驗仍被廣泛的使用測試奈米微粒毒性上。然而，對於呼吸暴露微粒毒性測試，近來越來越多研究者建議使用空氣-液界面 (air-liquid interface, ALI) 細胞暴露系統。因為ALI暴露實驗於氣液界面發生暴露行為的設計與真實情況較為相似，此可使實驗結果更具代表性，且細胞暴露的劑量亦較易準確的定量與控制。本研究設計建立一靜電收集式的ALI細胞株暴露氣懸微粒系統，並利用微粒電移動度掃瞄分徑器(SMPS)與螢光光度計(Fluorometer)作為量測儀器，分別定量通過暴露系統前後的微粒濃度及主要暴露區(培養皿)上的微粒沉積量，並利用暴露系統的貫穿率、區域沉積比率( f )及相對沉積密度(β)作為評估的指標。同時分別針對各個操作條件及可能影響因素(例如:微粒粒徑、通過暴露腔的氣流等因子)進行研究，瞭解微粒在氣液收集介面上分佈的均勻程度，以及提出準確估算微粒暴露劑量的方法。希望未來能依此而改進建立更精確、更具代表性、更簡易之評估作業場所空氣中微粒影響細胞株狀況之測試方法，提供應用奈米微粒細胞株危害測試結果進行危害分級管理之參考。研究中將結合貫穿率及區域沉積比率的實驗結果，建立暴露劑量方程式以利後續的細胞株試驗。除針對暴露系統內部的微粒沉積行為進行探討，研究為符合實際需求，另再針對搭配暴露系統的帶電裝置進行開發。前述的暴露劑量方程，僅只利用篩分後的單粒徑微粒作為測試對象，但在實際應用上，一般大氣中的奈米微粒可能較屬於多粒徑分布的狀態，且在帶電特性上也與篩分後的微粒有所不同；篩分後的微粒多數呈現單一電荷，大氣中的微粒則呈現出多數不帶電的狀況。因此為解決帶電行為對於ESP式ALI暴露系統的限制，本研究擬利用電噴霧針對帶電系統進行開發，而由實驗結果顯示，電噴霧系統對於研究中所使用的多粒徑微粒，在50 nm以上即具有改善的效果。研究中所開發的ESP式ALI暴露系統已可針對篩分後的單粒徑微粒進行良好的收集，且在利用多粒徑微粒作為研究對象時，則可利用帶電系統改善ESP式ALI暴露系統的效率。雖在研究中以初步實驗評估驗證系統的實用性，但其效率仍須透過實際的細胞株試驗進行估算。

關鍵字

奈米微粒；奈米毒理學； ESP式氣液式介面暴露系統

並列摘要

Currently, three methodologies, including animal experiments, ex vivo studies in vitro systems of exposure, are generally used to study adverse cellular effects induced by inhalable nanoparticles. Although, comparing to animal experiments, in vitro models lack the ability to account for all intercellular interactions in the cells, in vitro experimental setups are still widely employed due to its relatively low labor and capital cost. In addition, the in vitro studies can avoid the ethical issues provoked by animal experiments. Among the reported in vivo inhalation-exposure systems, the direct air-liquid interface (ALI) exposure method is considered as a more realistic experimental scheme, since its exposure scenario is more close to the real case. However, most of the ALI exposure systems reported in the literatures are not suitable for performing nanoparticle exposure experiments, due to the low collection efficiency of nanoparticles. In addition, very few studies addressed the issue of uniformity of particle deposition pattern over the exposed interface. In this study, a new ESP-type ALI exposure chamber was designed to improve the nanoparticle collection efficiency on the air-liquid exposure interface. The nanoparticle penetration tests were performed to validate the new design of ESP-type ALI chamber. Furthermore, the uniformity of the nanoparticle deposition pattern on the exposure interface is investigated by means of inspecting deposition pattern of fluorescein salt nanoparticle in the inner surfaces of the ALI chamber. At last, a semi-theoretical/semi-empirical expression was proposed to accurately estimate the exposed dose of nanoparticles.

並列關鍵字

Nanoparticle ； Nanotoxicity ； Cell exposure method

參考文獻

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靜電集塵式ALI暴露系統之設計、開發與評估

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