Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Dentistry, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Dentistry, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
Photodiagnosis Photodyn Ther. 2017 Sep;19:1-4. doi: 10.1016/j.pdpdt.2017.04.004. Epub 2017 Apr 13.
Dental caries are a multifactorial disease that progressively produces tooth destruction as a result of bacterial colonization of enamel surface, especially Streptococcus mutans. The objective of this work was to investigate the role of glucose in antimicrobial photodynamic therapy (aPDT) on S. mutans.
S. mutans ATCC 25175 were cultured on microaerophilia at 37°C for 48h, and we tested aPDT in the presence of 50mM glucose. Bacterial suspension was used to investigate aPDT with 100μM methylene blue (MB) under LED emitting radiation at ʎ=660nm and parameters as following (P=473 mW; I=166.8 mW/cm, and doses of 5, 10 and 20J/cm). A seventy-two hours biofilm was grown on 96 flat buttoned well-plate and irradiation was performed from 10 to 80J/cm at similar conditions.
There was no dark toxicity nor bacterial death regarding LED irradiation on suspension and on biofilm. Nevertheless, aPDT presented expressive bacterial inactivation following 1 and 2min of irradiation on cell suspension. On the other hand, there was no inactivation in the presence of glucose under the same conditions. Biofilm was completely inactivated by MB-mediated aPDT after 6min of irradiation. However, the presence of glucose delayed the complete inactivation of the biofilm.
The presence of glucose in the suspension drastically delayed the effect of aPDT on S. mutans and this effect is more pronounced in bacterial suspension than on biofilm.
龋齿是一种多因素疾病，由于细菌在牙釉质表面的定植，尤其是变形链球菌，会导致牙齿逐渐破坏。本研究旨在探讨葡萄糖在变形链球菌抗菌光动力疗法（aPDT）中的作用。
将变形链球菌 ATCC 25175 在微需氧条件下于 37°C 培养 48 小时，并在 50mM 葡萄糖存在的情况下测试 aPDT。用细菌悬浮液在 LED 发射辐射下，使用 100μM 亚甲蓝（MB）进行 aPDT 测试，波长为 ʎ=660nm，参数为（P=473mW；I=166.8mW/cm，剂量为 5、10 和 20J/cm）。在 96 个平底纽扣孔板上培养 72 小时生物膜，并在类似条件下从 10 到 80J/cm 进行照射。
在悬浮液和生物膜上，LED 照射均无暗毒性或细菌死亡。然而，在细胞悬浮液中照射 1 和 2 分钟后，aPDT 表现出显著的细菌失活作用。另一方面，在相同条件下，葡萄糖的存在阻止了 aPDT 的细菌失活作用。在存在葡萄糖的情况下，生物膜经过 6 分钟的 MB 介导的 aPDT 照射后被完全失活。然而，葡萄糖的存在延迟了生物膜的完全失活。
在悬浮液中存在葡萄糖极大地延迟了 aPDT 对变形链球菌的作用，这种作用在细菌悬浮液中比在生物膜中更为明显。
