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Evaluation of the fototoxic and fotobiomodulador effects of different wavelengths of light emitting diode (LED) radiation on human cells and micro-organims


The widespread use of light emitting diodes (LED) as a light source for medical applications has caused concerns about the safety of this technology, especially when high energy radiation is used. Thus, the objective of this study is to evaluate the biological and antimicrobial effects of LED light at different wavelengths and light doses with the aim to provide new applications with greater efficiency and security in phototherapy. Therefore, this project is divided into two steps, described below: Objective 1: To assess the effects of phototherapy mediated by LED light in the blue (420 nm), red (630 nm), yellow (590 nm) and white wavelength (multichromatic) on human cells; and Objective 2: to evaluate the antimicrobial activity of phototherapy mediated by LED light in the same wavelengths used in objective 1. For this purpose, in the objective 1 keratinocytes skin (HaCaT), oral fibroblasts (HGF) and keratinocytes of the oral mucosa (Nok-si) will grow in microplates and subjected to successive applications of LEDs (blue, red, yellow and white) at light doses established at a screening. Then, it will be performed tests for assessing the cell viability, membrane damage, cell cycle analysis, oxidative stress and detection of inflammatory cytokines. For the achievement of the objective 2, standard cell suspensions of Candida albicans and Staphylococcus aureus will be subjected to successive applications at light doses established at a screening. Then, cells are seeded in culture medium specific for the analysis of cell viability by colony forming units. For treatments that result in significant reduction in the cell viability, a set of further analysis will be performed such as: a) analysis of the production of reactive oxygen species (ROS), b) lipid peroxidation, c) genotoxicity and d) analysis of gene expression of the enzyme related to DNA repair - Topoisomerase II. The data of the research will be analyzed by the most appropriate statistical test. (AU)