Department of Biosciences and Oral Diagnosis, School of Dentistry of São José dos Campos, UNESP - Univ Estadual Paulista, Francisco José Longo 777, São José dos Campos, São Dimas, CEP: 12245-000, SP, Brazil.
Lasers Med Sci. 2011 May;26(3):341-8. doi: 10.1007/s10103-010-0852-3. Epub 2010 Nov 11.
The purpose of this study was to evaluate specific effects of photodynamic inactivation (PDI) using methylene blue as photosensitizer and low-power laser irradiation on the viability of single-, dual-, and three-species biofilms formed by C. albicans, S. aureus, and S. mutans. Biofilms were grown in acrylic discs immersed in sterile brain heart infusion broth (BHI) containing 5% sucrose, inoculated with microbial suspension (10(6) cells/ml) and incubated for 5 days. On the fifth day, the effects of the methylene blue (MB) photosensitizer at a concentration of 0.1 mg/ml for 5 min and InGaAlP laser (660 nm) for 98 s, alone and conjugated were evaluated. Next, the discs were placed in tubes with sterile physiological solution [0.9% sodium chloride (NaCl)] and sonicated for to disperse the biofilms. Ten-fold serial dilutions were carried and aliquots seeded in selective agar, which were then incubated for 48 h. Then the numbers CFU/ml (log(10)) were counted and analyzed statistically (ANOVA, Tukey test, p < 0.05). Scanning electron microscopy (SEM) on discs treated with PDI and control biofilms groups was performed. Significant decreases in the viability of all microorganisms were observed for biofilms exposed to PDI mediated by MB dye. Reductions (log(10)) of single-species biofilms were greater (2.32-3.29) than the association of biofilms (1.00-2.44). Scanning electron microscopy micrographs suggested that lethal photosensitization occurred predominantly in the outermost layers of the biofilms. The results showed that PDI mediated by MB dye, might be a useful approach for the control of oral biofilms.
本研究旨在评估使用亚甲蓝作为光敏剂和低功率激光照射对白色念珠菌、金黄色葡萄球菌和变形链球菌单种、两种和三种生物膜的活性的特定影响。生物膜在无菌脑心浸液肉汤（BHI）中生长，其中含有 5%蔗糖，用微生物悬浮液（10(6)细胞/ml）接种，并孵育 5 天。在第 5 天，评估了浓度为 0.1mg/ml 的亚甲蓝（MB）光敏剂 5 分钟和 InGaAlP 激光（660nm）98s 的单独和共轭的作用。然后，将圆盘放入装有无菌生理盐水[0.9%氯化钠（NaCl）]的管中，并进行超声处理以分散生物膜。进行十倍系列稀释，并将等分试样接种在选择性琼脂上，然后孵育 48 小时。然后统计计数 CFU/ml（log(10)）并进行统计分析（ANOVA，Tukey 检验，p<0.05）。对经 PDI 处理的圆盘和对照生物膜组进行扫描电子显微镜（SEM）检查。暴露于由 MB 染料介导的 PDI 的所有微生物的生物膜活性均明显降低。与生物膜关联相比，单种生物膜的减少（log(10)）更大（2.32-3.29）（1.00-2.44）。扫描电子显微镜照片表明，致死光敏化主要发生在生物膜的最外层。结果表明，MB 染料介导的 PDI 可能是控制口腔生物膜的一种有用方法。
