- 學位論文
奈米銀/天然黏土之改質製備及其物理化學性質研究和抗菌應用評估
Preparation, characterization and anti-microbials application of Nanosilver/Clays
摘要
摘要 一般而言，奈米銀分散在高分子基材時，會有很嚴重的團聚現象，因而降低其抗菌作用；為改善此情況，本論文以天然黏土礦物作為抗菌機材的載體，因黏土本身主結構帶負電荷會與銀陽離子緊密結合，使銀離子得以分散，繼而將銀離子還原成銀原子，以有效釋放出銀原子達到抗菌功效。實驗方法是以蒙脫土為載體，加入硝酸銀(AgNO3)，使解離之銀離子得以離子交換反應插層至黏土層間，再以還原劑硼氫化鈉(NaBH4)將銀離子還原成奈米銀粒子(AgNPs)，製備出奈米銀顆粒/黏土(AgNPs/Clay)，使得奈米銀粒子得以分散，此舉可減少銀的用量，增加總接觸面積，有效接觸菌液，提升其抗菌能力。此外本論文也以兩種不同陽離子交換當量之蒙脫土(CL120和CL42)進行改質，分別添加1%、5%、10%NaBH4以製備出含不同銀還原量的基材，以進一步比較不同還原當量之蒙脫土所製備出之奈米銀顆粒/黏土(AgNPs/Clay)的抗菌效用。實驗結果顯示，利用廣角繞射分析儀(XRD)、熱重損失分析儀(TGA)來加以鑑定銀原子的結構與含量，在添加1%、5%、10% NaBH4所製備的AgNPs/Clay-CL42，所測得之銀還原量分別為17.1%、21.5% 和 22.5%，而在添加1%、5%、10% NaBH4所製備的AgNPs/Clay-CL120，所測得之銀還原量則分別為7.9%、11.0%、12.7%；而利用掃描式電子顯微鏡(SEM)與穿透式電子顯微鏡(TEM)觀察奈米銀粒子的大小與形態，顯示AgNPs粒徑大小約介於20~50 nm間，並隨著硼氫化鈉還原劑添加量增加其AgNPs也隨之增加。在抗菌效能方面，將合成好的AgNPs/Clay分別加入細菌(革蘭氏陰性菌:大腸桿菌Escherichia coli和綠膿桿菌Pseudomonas aeruginosa; 革蘭氏陽性菌:金黃色葡萄球菌Staphylococcus aureus)與真菌(酵母菌Saccharomyces cerevisiae) 2小時後，進行染色，觀察其對細胞之形態與增生影響，結果顯示AgNPs/Clay可破壞細菌之細胞完整性，進而影響其增生，而對酵母菌雖未見明顯之細胞破壞，但亦會影響其增生；另外本論文也以添加不同量之AgNPs/Clay進行抗菌活性之定量測試，結果顯示：AgNPs/Clay-CL42對大腸桿菌、綠膿桿菌、金黃色葡萄球菌和酵母菌之抗菌效果分別為81.5%、100%、48.1% 和24.6%，而AgNPs/Clay-CL120對上述微生物之抗菌效果則分別為97.6%、100%、52.2% 和52.8%，顯示AgNPs/Clay對革蘭氏陰性菌具較佳抗菌效果，而且AgNPs/Clay-CL120之抗菌效果亦較AgNPs/Clay-CL42為佳。因此，總結本論文以具不同還原當量之CL120及CL42蒙脫土為基材，分別添加不同含量之硼氫化鈉還原劑，製備不同銀還原量之成品，經物理、化學鑑定分析與抗菌功效評估，顯示此製程可使奈米銀粒子分散於基材中，並達到抗菌效果。
並列摘要
Abstract Although nanosilver has high anti-microbial capability, the self-aggregation and hard-to-dispersion property of nanosilver render its limitations on the anti-microbial applications. To overcome these problems, natural clays, montmorillonite, were applied as the carrier of nanosilver. Firstly, silver nitrate (AgNO3) was added and the dissociated silver ion would intercalate into the layers of clays. Then a reducing agent, sodium borohydride (NaBH4), was added to reduce silver ions into silver nanoparticles (AgNPs) in the clays. These AgNPs/Clays are expected to contact effectively with microbes to enhance their anti-microbial effects. In this thesis, two modified montmorillonite (CL120 and CL42) with different cation-exchanging capacity were used to prepare the AgNPs/Clay. And XRD, TGA, FT-IR, SEM and TEM are utilized to examine the content, morphology and distribution of nanosilver in AgNPs/Clay. The size of AgNPs ranged from 20 to 50 nm and randomly dispersed in the Clay. The calculated Ag reductant in CL42 and CL120 is 17.1%, 21.5%, 22.5% and 7.9%, 11.0%, 12.7%, respectively. In the microscopic observation of the AgNPs/Clay on E. coli, P. aeruginosa, S. aureus and S. cerevisiae, AgNPs/Clay can severely disrupt the bacteria, but less on yeasts which still maintain their structural integrity. In the aspect of anti-microbial property, E. coli, P. aeruginosa, S. aureus and S. cerevisiae were used to test their anti-microbial effect. The best anti-microbial ability of AgNPs/Clay-CL120 to E. coli, P. aeruginosa, S. aureus and S. cerevisiae is 97.6%, 100%, 52.2%, and 52.8%, respectively. And the anti-microbial effect of AgNPs/Clay-CL42 is 81.5%, 100%, 48.1%, and 24.6%, respectively.These results demonstrated that both kinds of AgNPs/Clays show higher anti-microbial ability to Gram negative bacteria and AgNPs/Clay-CL120 has higher anti-microbial ability than AgNPs/Clay-CL42.
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