Prates Renato Araújo, Yamada Aécio Massayoshi, Suzuki Luis Cláudio, Eiko Hashimoto Maria Cristina, Cai Silvana, Gouw-Soares Sheila, Gomes Laércio, Ribeiro Martha Simões
Center for Lasers and Applications, IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242, Cidade Universitária, São Paulo SP 05508-000, Brazil.
J Photochem Photobiol B. 2007 Jan 3;86(1):70-6. doi: 10.1016/j.jphotobiol.2006.07.010. Epub 2006 Sep 18.
The aim of this study was to investigate the ability of malachite green (MG) combined with a low-power red laser to kill Actinobacillus actinomycetemcomitans and to investigate MG photodegradation after photodynamic therapy (PDT) by optical absorption spectroscopy. The etiology of periodontal disease is that microorganisms form a bacterial biofilm on the surface of the teeth. It is an infectious disease and A. actinomycetemcomitans is considered an important agent in biofilm ecology. Instead of using antibiotics, PDT is an alternative approach to eradicate bacteria. Cultures of A. actinomycetemcomitans were exposed to a 30 mW diode red laser, in the presence or absence of MG. A group of cultures was treated in dark conditions in the presence of MG (0.01% w/v) for 5 min. In the presence of MG, two exposure times for laser irradiation were used: t=3 min (energy dose=5.4 J/cm(2)), and t=5 min (energy dose=9 J/cm(2)). The samples were diluted and bacterial colonies were counted and converted into colony forming units. Absorption spectra of the bacterial suspensions, MG, MG-stained bacterial suspensions, and photosensitized bacterial suspensions were obtained. A. actinomycetemcomitans can be photoinactivated by a red laser in the presence of MG. Significant differences were observed between the two energy doses used (p<0.05). Red laser alone and MG alone were not able to kill bacteria. Optical absorption showed that MG is photobleached after irradiation. These results indicate that A. actinomycetemcomitans can be photosensitized by red laser combined with MG and that the dye is photodegraded following irradiation.
本研究的目的是探究孔雀石绿（MG）联合低功率红色激光杀灭伴放线放线杆菌的能力，并通过光吸收光谱法研究光动力疗法（PDT）后MG的光降解情况。牙周病的病因是微生物在牙齿表面形成细菌生物膜。它是一种传染病，伴放线放线杆菌被认为是生物膜生态中的重要病原体。光动力疗法是一种根除细菌的替代方法，而非使用抗生素。伴放线放线杆菌培养物在有或无MG的情况下，暴露于30 mW二极管红色激光下。一组培养物在黑暗条件下，于含MG（0.01% w/v）的环境中处理5分钟。在有MG的情况下，使用了两个激光照射时间：t = 3分钟（能量剂量 = 5.4 J/cm²）和t = 5分钟（能量剂量 = 9 J/cm²）。将样品稀释并计数细菌菌落，转化为菌落形成单位。获得了细菌悬浮液、MG、MG染色的细菌悬浮液和光敏化细菌悬浮液的吸收光谱。在有MG的情况下，伴放线放线杆菌可被红色激光光灭活。所使用的两种能量剂量之间观察到显著差异（p < 0.05）。单独的红色激光和单独的MG均无法杀灭细菌。光吸收显示，照射后MG发生了光漂白。这些结果表明，伴放线放线杆菌可被红色激光联合MG光敏化，且照射后该染料发生了光降解。
