Evaluation of antimicrobial photodynamic therapy on heterogeneous cariogenic biofilm mediated by chloro-aluminum phthalocyanine encapsulated in chitosan nanoparticles

Abstract

Antimicrobial photodynamic therapy (aPDT) using chloro-aluminum phthalocyanine exhibit efficient production of singlet oxygen and has high oxidative power, being an alternative for the control of cariogenic biofilms, maintaining its photophysical and photochemical properties when administered in release vehicles. The wide spectrum of antimicrobial action, low toxicity and polycatalytic nature of chitosan appears as a possibility to increase the effectiveness of chloro-aluminum phthalocyanine-mediated aPDT encapsulated in chitosan nanoparticles on cariogenic biofilms and treatment of caries lesions. The aim of this study was to evaluate the effect of antimicrobial photodynamic therapy using the chloro-aluminum phthalocyanine encapsulated in chitosan nanoparticles against S. mutans (ATCC 25175), L. acidophilus (ATCC 4356), A. viscosus (ATCC 15987) and L. rhamnosus (ATCC 7469) biofilms, through bacterial viability, analysis of lactic acid production and analysis of biofilm morphology. The low-intensity diode laser (InGaAlP) will be used in the infrared spectrum, with wavelength of 660 nm and energy density of 100 J / cm2. The specimens will be randomly divided into 7 groups (n = 10): 0.12% chlorhexidine digluconate (CHX, positive control); phosphate buffered saline (PBS, negative control); 2.5% chitosan solution in acid medium (QT, release vehicle control); antimicrobial photodynamic therapy using chloro-aluminum phthalocyanine (aPDT ClAlPc) and antimicrobial photodynamic therapy with chloro-aluminum phthalocyanine encapsulated in chitosan nanoparticles (aPDT ClAlPc / QT); non-irradiated chloro-aluminum phthalocyanine in organic medium (ClAlPc, dark toxicity control of the photosensitizer); non-irradiated chloro-aluminum phthalocyanine encapsulated in chitosan nanoparticles (ClAlPc / QT, dark toxicity control of the encapsulated photosensitizer). Heterogeneous cariogenic biofilms will be grown for 5 days on bovine dentin blocks at 37 ° C. At the end of 5 days, biofilms will be collected and analyzed qualitatively by scanning electron microscopy (SEM) and the number of viable bacteria, , the concentration of extracellular insoluble polysaccharides (PECI) and intracellular (ICP) , and the quantification of lactic acid will be analyzed statistically. (AU)