Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien, Taiwan, ROC.
Arch Immunol Ther Exp (Warsz). 2012 Aug;60(4):267-75. doi: 10.1007/s00005-012-0178-x. Epub 2012 Jun 8.
This review focuses on the antibacterial activities of visible light-responsive titanium dioxide (TiO(2)) photocatalysts. These photocatalysts have a range of applications including disinfection, air and water cleaning, deodorization, and pollution and environmental control. Titanium dioxide is a chemically stable and inert material, and can continuously exert antimicrobial effects when illuminated. The energy source could be solar light; therefore, TiO(2) photocatalysts are also useful in remote areas where electricity is insufficient. However, because of its large band gap for excitation, only biohazardous ultraviolet (UV) light irradiation can excite TiO(2), which limits its application in the living environment. To extend its application, impurity doping, through metal coating and controlled calcination, has successfully modified the substrates of TiO(2) to expand its absorption wavelengths to the visible light region. Previous studies have investigated the antibacterial abilities of visible light-responsive photocatalysts using the model bacteria Escherichia coli and human pathogens. The modified TiO(2) photocatalysts significantly reduced the numbers of surviving bacterial cells in response to visible light illumination. They also significantly reduced the activity of bacterial endospores; reducing their toxicity while retaining their germinating abilities. It is suggested that the photocatalytic killing mechanism initially damages the surfaces weak points of the bacterial cells, before totally breakage of the cell membranes. The internal bacterial components then leak from the cells through the damaged sites. Finally, the photocatalytic reaction oxidizes the cell debris. In summary, visible light-responsive TiO(2) photocatalysts are more convenient than the traditional UV light-responsive TiO(2) photocatalysts because they do not require harmful UV light irradiation to function. These photocatalysts, thus, provide a promising and feasible approach for disinfection of pathogenic bacteria; facilitating the prevention of infectious diseases.
本综述聚焦于可见光响应型二氧化钛（TiO2）光催化剂的抗菌活性。这些光催化剂具有广泛的应用，包括消毒、空气和水净化、除臭以及污染和环境控制。二氧化钛是一种化学稳定且惰性的材料，在光照下可以持续发挥抗菌作用。其能源可以是太阳光；因此，TiO2 光催化剂在电力不足的偏远地区也很有用。然而，由于其激发的能带隙较大，只有生物危害的紫外（UV）光照射才能激发 TiO2，这限制了其在生活环境中的应用。为了扩展其应用，通过金属涂层和控制煅烧进行杂质掺杂，成功地修饰了 TiO2 的基质，将其吸收波长扩展到可见光区域。先前的研究已经使用模型细菌大肠杆菌和人类病原体研究了可见光响应型光催化剂的抗菌能力。改性后的 TiO2 光催化剂在可见光照射下显著减少了存活细菌细胞的数量。它们还显著降低了细菌芽孢的活性，在保留其发芽能力的同时降低了其毒性。据推测，光催化杀菌机制最初会破坏细菌细胞的表面弱点，然后破坏细胞膜。然后，内部细菌成分通过受损部位从细胞中渗出。最后，光催化反应氧化细胞残骸。总之，可见光响应型 TiO2 光催化剂比传统的 UV 光响应型 TiO2 光催化剂更方便，因为它们不需要有害的 UV 光照射就能发挥作用。这些光催化剂为消毒致病菌提供了一种有前景且可行的方法，有助于预防传染病。
