In vitro experiments confirmed that antibacterial photodynamic treatment (aPDT) inactivates periodontal pathogens. However, more effective sterilization is needed in the complex oral environment. This study tested whether dihydroartemisinin (DHA) enhanced the photokilling effect of aPDT on Porphyromonas gingivalis(P. gingivalis) in planktonic and biofilm states. aPDT combining toluidine blue O (TBO) with 630 nm red light was performed on bacterial suspensions and biofilms in vitro with different final concentrations of DHA (10 μg/mL, 20 μg/mL and 40 μg/mL). The sensitization mechanism was preliminarily investigated by uptake experiments. The above experiments were repeated with different incubation times (30 s, 60 s, 120 s). P. gingivalis biofilms exhibited significantly higher resistance to aPDT than P. gingivalis in suspension under the same experimental parameters. DHA alone had no cytotoxic effect on P. gingivalis with or without light irradiation. In either bacterial suspensions or biofilms, DHA concentration-dependently enhanced the photokilling effect of aPDT and increased TBO uptake by P. gingivalis. Prolonged incubation time enhanced the photokilling efficiency of aPDT until cellular TBO uptake reached saturation. DHA can enhance aPDT activity against P. gingivalis in planktonic and biofilm states. DHA also accelerated TBO uptake, reducing incubation time.

中文翻译：

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甲苯胺蓝 O 和双氢青蒿素增强的非激光红光源对牙龈卟啉单胞菌的抗菌光动力治疗

体外实验证实，抗菌光动力治疗 (aPDT) 可灭活牙周病原体。然而，复杂的口腔环境需要更有效的杀菌。本研究测试了双氢青蒿素 (DHA) 是否增强了 aPDT 对处于浮游和生物膜状态的牙龈卟啉单胞菌 (P. gingivalis) 的光杀作用。结合甲苯胺蓝 O (TBO) 和 630 nm 红光的 aPDT 在体外用不同终浓度 DHA（10 μg/mL、20 μg/mL 和 40 μg/mL）对细菌悬浮液和生物膜进行。通过摄取实验初步研究了致敏机制。以不同的孵育时间（30 s、60 s、120 s）重复上述实验。P. gingivalis 生物膜对 aPDT 的抗性明显高于 P. gingivalis 生物膜。在相同的实验参数下牙龈悬浮。无论有无光照射，单独的 DHA 对牙龈卟啉单胞菌没有细胞毒性作用。在细菌悬浮液或生物膜中，DHA 浓度依赖性地增强了 aPDT 的光杀作用，并增加了牙龈卟啉单胞菌对 TBO 的摄取。延长孵育时间可提高 aPDT 的光杀伤效率，直至细胞 TBO 摄取达到饱和。DHA 可以增强 aPDT 对浮游和生物膜状态下牙龈卟啉单胞菌的活性。DHA 还加速了 TBO 的吸收，减少了孵育时间。延长孵育时间可提高 aPDT 的光杀伤效率，直至细胞 TBO 摄取达到饱和。DHA 可以增强 aPDT 对浮游和生物膜状态下牙龈卟啉单胞菌的活性。DHA 还加速了 TBO 的吸收，减少了孵育时间。延长孵育时间可提高 aPDT 的光杀伤效率，直至细胞 TBO 摄取达到饱和。DHA 可以增强 aPDT 对浮游和生物膜状态下牙龈卟啉单胞菌的活性。DHA 还加速了 TBO 的吸收，减少了孵育时间。