Bactericidal Activity of TiO2 Nanotube Thin Films on Si by Photocatalytic Generation of Active Oxygen Species
Bactericidal Activity of TiO2 Nanotube Thin Films on Si by Photocatalytic Generation of Active Oxygen Species
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DOI：
10.1021/acs.langmuir.0c02225
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发表时间：
2020-10-27
期刊：
影响因子：
3.9
通讯作者：
Niwano, Michio
中科院分区：
文献类型：
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作者：
Yamaguchi, Masato;Abe, Hiroyuki;Niwano, Michio
二氧化钛（TiO₂）薄膜的光催化杀菌活性已被广泛研究。在本研究中，我们以大肠杆菌和金黄色葡萄球菌细胞为模式细菌，研究了TiO₂纳米管（NT）薄膜的杀菌活性。在硅（Si）晶片基底上对金属钛（Ti）薄膜进行阳极氧化，以形成TiO₂ NT薄膜。为了评估TiO₂ NT薄膜的杀菌活性，用波长为365 nm的近紫外光（UV - A）照射TiO₂ NT薄膜上的细菌。杀菌活性通过活细胞数量得出的存活率来评估，活细胞能在细胞培养基上形成菌落。我们证明了本研究中所考察的两种细菌的存活率在紫外光照射下显著降低，并且两种细菌的存活率随时间的变化存在差异。此外，我们利用电子自旋共振光谱和荧光分析研究了TiO₂ NT薄膜在紫外光照射下活性氧物质（ROS）的产生。我们发现TiO₂ NT薄膜表面产生的主要ROS是羟基自由基（OH·）。而且，ROS的产生随着紫外照射时间的增加而增加。我们提出了一个动力学模型，该模型通过考虑紫外光照射产生的ROS量随时间的变化来重现细菌存活率对紫外光照射时间的依赖性。计算结果和实验结果的比较表明，杀菌效果由细菌的直接光解和通过产生羟基自由基的光催化作用组成，后者比前者具有更强的杀菌效果。
The photocatalytic bactericidal activity of titanium dioxide (TiO2) thin films has been extensively studied. In this study, we investigated the bactericidal activities of TiO2 nanotube (NT) thin films using Escherichia coli and Staphylococcus aureus cells as the model bacteria. Metallic titanium (Ti) thin films were anodized on a silicon (Si) wafer substrate to form TiO2 NT thin films. To evaluate the bactericidal activity of the TiO2 NT thin films, bacteria on the TiO2 NT thin films were irradiated with near-ultraviolet light (UV-A) at a wavelength of 365 nm. The bactericidal activity was estimated by the survival rate derived from the number of live cells, which form colonies on the cell culture medium. We demonstrated that the survival rate of the two types of bacteria investigated in this study was significantly reduced by UV light irradiation and that there was a difference in the temporal change in the survival rate between the two types of bacteria. Furthermore, we investigated the generation of reactive oxygen species (ROSs) by UV light irradiation of TiO2 NT thin films using electron spin resonance spectroscopy and fluorescence analysis. We found that the main ROS generated on the surface of the TiO2 NT film was the hydroxyl radical, OH center dot. In addition, the generation of ROSs increased with an increase in the UV irradiation time. We proposed a kinetic model that reproduces the dependence of bacterial viability on the UV light irradiation time by considering the temporal change in the amount of ROSs generated by UV light irradiation. A comparison of the calculated and experimental results revealed that the bactericidal effect consisted of the direct photolysis of bacteria and the photocatalysis via the generation of hydroxyl radicals, with the latter exhibiting a stronger bactericidal effect than the former.