金屬有機骨架材料之抗菌能力與機制研究

Abstract

位於亞熱帶地區的台灣終年溫暖潮濕，食物保存不當，微生物容易大量繁殖並產生毒素，因此食品中毒事件發生頻率高。研發新型抗菌材料，使之具有更佳抗菌效果並提高其應用性為刻不容緩的目標。過去研究指出奈米金屬粒子對抑制革蘭氏陽性菌及陰性菌的生長皆有功效，而殺菌的原因可能為氧化壓力之提高、金屬離子之釋出及非氧化機制。金屬有機骨架材料由有機配位基與金屬離子所組成，具有多孔洞及大表面積的特性。本計畫中我們選用以銅金屬離子為節點的HKUST-1、鋁金屬離子為節點的MIL-53、MIL-68、MOG及鐵金屬離子為節點的MIL-88B、MIL-100，以MIC、MBC Assay及Disk diffusion test針對引起食物中毒的主要病原菌作為研究對象：革蘭氏陽性菌的蠟樣芽孢桿菌與金黃色葡萄球菌；革蘭氏陰性菌的大腸桿菌以及對抗生素抗性高的綠膿桿菌進行抗菌能力檢測，藉由H2DCF-DA螢光探針檢測細菌體內氧化壓力，以及FDAAs螢光探針檢測細胞壁合成活性。實驗結果顯示HKUST-1對本研究所選用的目標菌種具有最佳的抗菌效果，菌體內部氧化壓力增加，細胞壁合成能力受到抑制，僅於以上我們可以發現HKUST-1是經由多重機制以達到抗菌效果。

The subtropical climate of Taiwan makes food preservation difficult to achieve. Microorganisms tend to multiply and produce toxins in warm and humid environment, causing high frequency of food poisoning incidents. In this study, we aimed to develop a new nanomaterial with better antibacterial effect and improved applicability. Previous studies revealed that metallic nanoparticles (NPs) exhibited antibacterial properties against both Gram-positive and Gram-negative bacteria. The underlined mechanism for their antibacterial activities include elevated oxidation pressure, metal ion release and non-oxidation mechanism. Metal-organic frameworks (MOFs) are comprising nanomaterials consisting of metal ions and organic binding ligands, that are highly porous with large surface area. Three metal organic framework materials: (1) HKUST-1 with copper metal ion as the node, (2) MOF-53, MOF-68 and MOG with aluminum metal ions as the node and (3) MIL-88B and MIL-100 with iron metal ion as the node, were under investigation for their antibacterial activities, while four bacteria were selected for study, including Gram-positive bacteria Bacillus cereus and Staphylococcus aureus, and Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa with high resistance to antibiotics. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) of the MOFs were determined by visual turbidity analysis, optical density analysis and disk diffusion test, respectively. The oxidative pressure in the bacteria was detected by H2DCF-DA fluorescent probe, and the cell wall synthesis activity was detected by FDAAs fluorescent probe. Our results showed that copper-containing HKUST-1 demonstrated the best antibacterial effect among all, including increased internal oxidative stress, inhibited cell wall synthesis, and change in average size of bacteria. Taken all together, antibacterial effects of the HKUST-1 may involve multiple mechanisms of action.