一個可產生穩定數目濃度的粉體分散系統及其奈米碳管毒性測試之應用

Abstract

本研究以一套可以產生穩定濃度並長時間穩定的震盪流體化床-噴霧粉體分散系統(Shaker-Fluidized bed-Atomizer disperser, SFA)，此分散系統係由霧化器(Atomizer)、粉體儲存容器(Powder Storage Container)、支撐底座(Supporting Base)和迴轉式震盪器(Orbital Shaker)所組成，粉體分散器底部藉由通入一道底部分散流量(Qdis=0.5 L/min)使裝載至分散器腔體中的奈米粉體懸浮於腔體中，再藉由35 psi的高壓氣體經過臨界流孔板時產生的高速氣體，將分散器內部的奈米級粉體抽出，因高速氣體產生的剪應力(Shear Force)將粉體分散，以產生濃度穩定的奈米粉體。研究中主要分散未純化多壁奈米碳管(Multi-walled Carbon Nanotube, MWCNT)與純化多壁奈米碳管(Purified Multi-walled Carbon Nanotube, P-MWCNT)後進行奈米碳管物化特性的量測與應用於動物吸入性暴露試驗。 實驗中量測奈米碳管經分散後的各種物化特性，如：數目濃度分佈、質量濃度分佈、即時質量濃度、即時表面積濃度及以穿透式電子顯微鏡(Transmission Electron Microscopy, TEM, Philips, TECNAI 20)觀察形貌等，除此之外也量測奈米碳管在純化前後的純度分析以及官能基是否有改變。結果顯示，MWCNT與P-MWCNT在數目濃度分佈皆呈現雙峰分佈，峰值分別為165、453 nm與124、453 nm；P-MWCNT在質量濃度分佈中的質量中間氣動直徑MMAD (Mass Median Aerodynamic Diameters, MMAD)較MWCNT小；即時質量與表面積濃度以MWCNT較P-MWCNT高；MWCNT在純化後有-COOH官能基的出現。 動物實驗部分係將SFA分散系統與國家衛生研究院的奈米微粒暴露腔系統(Nanoparticle Exposure Chamber System, NECS)結合，並進行每天4小時，持續5天的高濃度MWCNT、低濃度MWCNT及低濃度P-MWCNT的三組小鼠暴露實驗，並在暴露完成後的第3天進行各項生理、血液生化及病理檢驗。結果顯示，各組暴露後造成肺功能變化的嚴重程度依序為高濃度MWCNT >低濃度MWCNT>低濃度P-MWCNT，並且由病理組織分析可以看出高濃度MWCNT的暴露組有明顯的肺發炎、肺泡壁增厚與類似間質性肺炎的情形。P-MWCNT因分散特性較MWCNT良好，在小鼠肺部有最高的沉積量，然而並未造成最嚴重的生物效應，可能原因為P-MWCNT的分散性佳且被許多呼吸道表面的蛋白質所包圍，加上本研究僅進行了一周的動物暴露實驗及短期的追蹤，無法觀察到長時間才會發生的症狀。

In this study, a Shaker-Fluidized bed-Atomizer disperser (SFA) powder dispersion system consist of an atomizer, powder storage container, supporting base and orbital shaker with 0.5 L/min dispersion flow rate and 35 psi compressed air was used to generate long-term stable concentration and well-dispersed multi-wall carbon nanotube (MWCNT) and purified multi-wall carbon nanotube (P-MWCNT). The physicochemical properties both of MWCNT and P-MWCNT dispersed by SFA such as number distribution, mass distribution, morphology, real-time mass concentration and surface area concentration were measured before animal inhalation exposure test. In addition, the purity and functional groups of MWCNT and P-MWCNT were also measured. The result of mass distribution shows bimodal distribution with 0.26、3.05 µm and 0.18、1.28 µm of MMAD for MWCNT and P-MWCNT, respectively. Also the carbonyl group (-COOH) appeared on the surface of P-MWCNT after purification. To investigate biological effects of MWCNT and P-MWCNT on animal, the SFA dispersion system was combined with Nanoparticle Exposure Chamber System (NECS) in NHRI to conduct whole-body inhalation exposure at high dose MWCNT (MWCNT-HD), low dose MWCNT (MWCNT-LD) and low dose P-MWCNT (P-MWCNT-LD) exposure groups for 4 hour per day and 5 days per test. Results indicated that the severity of pulmonary function impairment from high to low was MWCNT-HD, MWCNT-LD and P-MWCNT-LD. The results of histopathology also showed obvious inflammation, alveolar wall thicken and interstitial pneumonia-like histopathological outcomes caused by MWCNT-HD exposure. Due to better dispersion, P-MWCNT showed the highest deposition amounts in lung but did not present the most serious biological responses. The study proposed protein corona adsorbed on P-MWCNT eliminating acute phase biological responses and the short-term observation after one-week exposure was not able to present chronic effects.