M.A. Calin, R. Savastru, M.R. Calin, Spectral analysis of methylene blue-mediated photodynamic inactivation of bacteria using 635 nm diode laser, Spectroscopy Letters 46: 327-333, 2013 DOI:10.1080/00387010.2012.730598

Title: Spectral analysis of methylene blue-mediated photodynamic inactivation of bacteria using 635 nm diode laser

Abstract: In this paper we assess the efficacy of a laser system, emitting at 635 nm, in methylene blue–mediated photodynamic inactivation of Pseudomonas aeruginosa that contaminates wounds, using diffuse reflectance spectrometry. The spectral plots of the contaminated wounds were recorded before and after laser irradiation, and the refractive index and extinction coefficient were determined by Kramers-Kronig analysis of reflectance spectra. The changes in optical parameter values after the treatment were corroborated with bacterial counts determined by bacteriological examination. The results revealed that the combined treatment 635-nm laser–methylene blue is an efficient way to destroy the bacteria that contaminate the wounds.

Key words: bacteria, laser, photodynamic inactivation, reflectance, spectrum