Abstract

Antimicrobial photodynamic therapy (aPDT) has been considered as a potential alternative to antibiotics for the treatment of biofilm infections. There is evidence that an additional H₂O₂ enhances the antimicrobial efficacy of aPDT. However, the minimum H₂O₂ concentration to achieve this synergistic effect is unclear. A saliva-derived multi-species biofilm was treated with the photosensitizer chlorin e6 (Ce6, 50 µM), H₂O₂ (0.3, 3.3, 33.3 mM), or their combination for 5 min, followed by no irradiation or irradiation at 15 J (cm²)⁻¹ (λ = 450 nm or 660 nm), with or without oxygen. Biofilm viability and metabolic activity were evaluated. The combination of 33.3 mM H₂O₂ and Ce6-aPDT strongly enhanced antimicrobial efficacy compared with either component alone, irrespective of oxygen availability and irradiation wavelength. In particular, the combination resulted in a 6.6-log colony forming unit (CFU) reduction anaerobically under blue irradiation. This combination is a promising treatment for biofilm infections, especially those thriving in an anaerobic microenvironment.

摘要

抗菌光动力疗法 (aPDT) 已被认为是治疗生物膜感染的抗生素的潜在替代品。有证据表明额外的 H ₂ O ₂增强了 aPDT 的抗微生物功效。然而，实现这种协同效应的最小 H ₂ O ₂浓度尚不清楚。唾液衍生的多物种生物膜用光敏剂二氢卟酚 e6（Ce6，50 µM）、H ₂ O ₂（0.3、3.3、33.3 mM）或它们的组合处理 5 分钟，然后不照射或在 15 J (cm ² ) ^-1（λ = 450 nm 或 660 nm），有氧或无氧。评估生物膜活力和代谢活性。与单独的任一组分相比，33.3 mM H ₂ O ₂和 Ce6-aPDT的组合大大增强了抗菌功效，而与氧气可用性和辐照波长无关。特别是，该组合导致在蓝色照射下厌氧减少 6.6-log 菌落形成单位 (CFU)。这种组合是治疗生物膜感染的有希望的方法，尤其是那些在厌氧微环境中茁壮成长的生物膜感染。