Medical Microbiology and Molecular Biology Lab., Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India.
Medical Microbiology and Molecular Biology Lab., Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India.
J Photochem Photobiol B. 2018 Jun;183:16-21. doi: 10.1016/j.jphotobiol.2018.04.024. Epub 2018 Apr 16.
In photodynamic therapy (PDT), killing is entirely based on the ROS generation and among different types of ROS generated during PDT, singlet oxygen is considered as the most potential as illustrated in many studies and therefore it is predominantly responsible for photodamage and cytotoxic reactions. The aim of this study was to check whether singlet oxygen (Type II photochemistry) is more potential than free radicals (Type I photochemistry) against Streptococcus mutans biofilm. We have taken two phenothiazinium dyes i.e. toluidine blue O (TBO) and new methylene blue (NMB). TBO was found to have better antibacterial as well as antibiofilm effect than NMB. Antibacterial effect was evaluated by colony forming unit while antibiofilm action by crystal violet and congo red binding assays. We have also evaluated the disruption of preformed biofilm by biofilm reduction assay, confocal laser electron and scanning electron microscopy. More singlet oxygen production was detected in case of TBO than NMB while more Free radical (HO) was produced by NMB than TBO. TBO showed better antibacterial as well as antibiofilm effect than NMB so; we conclude that potency of a photosensitizer is correlated with the capability to produce singlet oxygen.
在光动力疗法（PDT）中，杀伤完全基于 ROS 的产生，而在 PDT 过程中产生的不同类型的 ROS 中，单线态氧被认为是最有潜力的，正如许多研究所示，因此它主要负责光损伤和细胞毒性反应。本研究旨在检查单线态氧（II 型光化学）是否比自由基（I 型光化学）对变形链球菌生物膜更有潜力。我们选择了两种吩噻嗪染料，即甲苯胺蓝 O（TBO）和新亚甲基蓝（NMB）。结果表明，TBO 具有比 NMB 更好的抗菌和抗生物膜作用。通过菌落形成单位评估抗菌作用，通过结晶紫和刚果红结合测定评估抗生物膜作用。我们还通过生物膜减少测定、共聚焦激光电子显微镜和扫描电子显微镜评估了对已形成生物膜的破坏。与 NMB 相比，TBO 产生了更多的单线态氧，而 NMB 产生的自由基（HO）比 TBO 多。TBO 显示出比 NMB 更好的抗菌和抗生物膜作用，因此我们得出结论，光敏剂的效力与产生单线态氧的能力相关。
