Avaliação do fotossensibilizador azul de metileno em diferentes formulações para uso em terapia fotodinâmica

Abstract

The present study evaluated different formulations of methylene blue (MB) with the aim to improve the antimicrobial effect of photodynamic therapy. Photophysical and photochemical properties and antimicrobial effect of the MB dissolved in different formulations: water (MB/water); 20% ethyl alcohol (MB/ethanol); 0,1% chitosan solution (MB/chitosan); and in mixture of water, ethanol and chitosan (50:20:30 v:v) (MB/new formulation), was evaluated. Molecular aggregation of MB, evaluated by monomer-to-dimer ratio, was dependent on MB concentration and the solvents used. The MB/water and MB/chitosan formulations showed higher aggregation than MB/ethanol and MB/new formulation. In substrate oxidation models (Uric acid and N-acetyl-l-tryptofanamide) the formulation MB/new formulation showed the greatest ability to form singlet oxygen and greater photo-oxidation kinetics. In vitro biofilms of Enterococcus faecalis (Gram positive) and Escherichia coli (Gram negative) was used to evaluated the antimicrobial effect of MB different formulations. No difference was observed when biofilms was treated with MB/water (Light +) and MB/water (Light -). The MB/new formulation group (Light +) showed significant decrease to MB/water (Light -) for both microorganisms. The MB formulation dissolved in water, ethanol and chitosan showed promising photochemical, photophysical, and antimicrobial results. Our results demonstrated that different solvents can enhanced the antimicrobial effect of photodynamic therapy.