STUDY OF THE AGGREGATION AND PHOTOBLEACHING DYNAMIC OF METHYLENE BLUE AND ORTO-TOLUIDINE BLUE AS REGARDS THEIR PHOTODYNAMIC EFFECTIVENESS / Estudo da dinâmica de fotodegradação e agregação das fenotiazinas azul de metileno e azul orto-toluidina com relação à eficiência fotodinâmica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Photodynamic therapy may be a viable alternative to treat localized infections, although to obtain a resourceful clinical application, parameters linked with photodynamic efficiency must be analyzed in order to achieve quantifiable results. The aims of this study were to investigate the aggregation dynamic of the photosensitizers methylene blue and orto-toluidine blue in different solvents; to characterize the solvents regarding to available molecular oxygen and pH; to observe the effect caused by temperature, blood and saliva on photosensitizer aggregation, to monitor the photobleaching dynamic as a function of fluence and irradiance, and to evaluate the photodynamic efficiency in such conditions. The tested solvents were deionized water, distillated water, sterile water, and saline solution 0.9%. In each solution, the pH and molecular oxygen availability were measured with the appropriated device. The effects of organic fluids, temperature and concentration on aggregation were analyzed through optical absorption spectroscopy. The photobleaching dynamic was tested regarding radiant exposure and irradiance with the appropriated wavelength for each compound. The irradiations were performed with broad band and narrow band light sources. The photodynamic efficiency was evaluated through singlet oxygen luminescence measurement in ?=1270nm and microbiological tests were performed with cultures of Escherichia coli. The results demonstrated that the aggregation dynamic is directly linked with solvent and concentration: the saline solution presented different results in all tested conditions. Deionized water presented the best results. The photobleaching dynamic is correlated in its magnitude with the radiant exposure and its dynamic is associated with irradiance. The use of broad band to perform the irradiation was considered more effective for lethal photosensitization. Therefore, for the clinical application of this therapy, the substrate must be taking into account, and appropriated parameters of irradiation and photosensitizer presentation increase the efficiency of the process.

ASSUNTO(S)

antimicrobianos terapia fotodinâmica led. led. fenotiazinas laser terapia fotodinâmica fenotiazinas laser antimicrobianos

ACESSO AO ARTIGO

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