Application and characterization of light-emitting diodes for photodynamic inactivation of bacteria

Abstract

Light- and photosensitizer-based antimicrobial photodynamic therapy (aPDI) is a very promising approach to control microbial infections. Other applications of aPDI are also being studied, for example, in water disinfection or food preservation. Because this technology is based on the use of light, the proper characterization of light sources is of prime importance. The aim of this study was to prepare and characterize three irradiation systems constructed for research purposes. These LED-based light sources produce visible light in the range of blue, green and red wavelengths. The efficacy and light distribution produced by the light sources were verified on a Staphylococcus aureus model sensitized with three photosensitizers: protoporphyrin IX diarginate, N-methylpyrrolidinium fullerene iodide (Full), and rose bengal. Antimicrobial blue light treatment was likewise investigated. The survival of bacterial cells after photoinactivation was determined for irradiance at three power densities. Based on the proper characterization of light emitted by each LED at each point of the illuminated area, a homogeneous distribution of light can be achieved, which is crucial for precise dosimetry.