本研究以纖維素為材料,使用奈米級介質研磨機,以由上而下(top-down)方式,將纖維素巨分子以機械力撞擊降解成奈米/次微米之纖維素顆粒懸浮液,並探討其性質與安全性。以肉眼觀察懸浮液、凍乾粉末以及烘乾粉末之差異,再使用光學顯微鏡觀察懸浮液中纖維素次顆粒的聚集情形、掃瞄式電子顯微鏡觀察凍乾粉末以及烘乾粉末之表面組成。形態觀察結果顯示奈米/次微米化纖維素和纖維素原料大不相同,並由雷射粒徑分析儀的粒徑分佈結果,確認奈米/次微米化纖維素懸浮液之顆粒組成大小為奈米/次微米等級。保水力方面,研磨過後之纖維素保水力比原料高約8.5倍,與比表面積增加量一致。安全性評估方面,以沙門氏菌逆突變試驗(Ames test)TA98、TA100菌系評估奈米/次微米纖維素之致突變性,結果皆顯示試驗組所有濃度之回復菌落數均無超過對照組兩倍以上,且亦無濃度效應,判定其不具有致突變性。細胞毒性試驗則顯示奈米/次微米纖維素對於目標接觸細胞株:鼠腸道細胞株IEC-6、人類皮膚纖維母細胞株WS1以及人類腸道上皮細胞株Caco-2均無顯著的細胞毒殺效應。本研究更進一步探討奈米/次微米纖維素的抗致突變性,以沙門氏菌逆突變試驗檢測TA98、TA100菌系抗4-NQO之能力,結果顯示奈米/次微米化纖維素於TA98菌系無顯著的抗致突變效果;TA100菌系則具有些微抗致突變效果。
In this research, nano/submicron cellulose suspension is produced by “top-down” approach of media milling. In this approach, raw cellulose is degraded by mechanical force, and its characteristics and safety is investigated as well. In addition, the morphological differences between raw and nano/submicron cellulose in suspension, freezed-dried powder and hot-air dried powder are also examined. The aggregation in cellulose suspension is observed by optical microscopy. The surface properties of freezed-dried and hot-air dried powder are observed by SEM. The produced Nano/submicron cellulose by media milling was morphologically different from raw cellulose, and the particle size lied in nano/submicron scale is reconfirmed by laser diffraction particle size analyzer. The water-holding capacity of milled cellulose is found to be 8.5 times higher than raw cellulose, and also reaches consistency with the increase of specific surface area. As for safety assessment, the mutagenicity is evaluated by Ames test. The results show that there is no genotoxicity in Salmonella typhimurium TA98 and TA100. Cytotoxicity is also investigated in vitro. For portal-of-entry toxicity of skin and entero-mucosa, there is no significant cytotoxic effect on rat normal small intestinal cell line IEC-6, human skin fibroblast WS1 and human colon adenocarcinoma Caco-2 from nano/submicron cellulose. Furthermore, antimutagenicity of nano/submicron cellulose against 4-NQO is also considered. The data shows that there is no significant antimutagenicity in TA98 strain, but a slight antimutagenic reveals in TA100 strain.