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Item Effects of antimicrobial photodynamic therapy with photodithazine® on methicillin-resistant Staphylococcus aureus (MRSA): Studies in biofilms and experimental model with Galleria mellonella(Elsevier) Souza, Beatriz Müller Nunes; Miñán, Alejandro Guillermo; Brambilla, Isabelle Ribeiro; Pinto, Juliana Guerra; Garcia, Maíra Terra; Junqueira, Juliana Campos; Ferreira-Strixino, JulianaStaphylococcus aureus infections are a severe health problem due to the high mortality rate. Conventional treatment of these infections is via the administration of antibiotics. However, its indiscriminate use can select resistant microorganisms. Thus, it is necessary to develop alternatives for antibiotic therapy. Antimicrobial Photodynamic Therapy (aPDT), a therapeutic method that associates a photosensitizer (PS), a light source with adequate wavelength to the PS, interacts with molecular oxygen generating reactive oxygen species responsible for cell inactivation, is a viable alternative. This work aimed to analyze, in vitro and in vivo, the action of aPDT with PS Photodithazine® (PDZ) on the methicillin-resistant S. aureus (MRSA) strain. In the in vitro method, the S. aureus biofilm was incubated with PDZ at 50 and 75 μg.mL−1 for 15 min, adopting the light dose of 25, 50, and 100 J/cm2. In addition, PS interaction, formation of reactive oxygen species (ROS), bacterial metabolism, adhesion, bacterial viability, and biofilm structure were evaluated by scanning electron microscopy. Subsequently, the strain was inoculated into models of Galleria mellonella, and the survival curve, health scale, blood cell analysis, and CFU/mL of S. aureus in the hemolymph were analyzed after aPDT. In the in vitro results, bacterial reduction was observed in the different PDZ concentrations, highlighting the parameters of 75 μg.mL−1 of PDZ and 100 J/cm2. As for in vivo results, aPDT increased survival and stimulated the immune system of G. mellonella infected by S. aureus. aPDT proved effective in both models, demonstrating its potential as an alternative therapy in treating MRSA bacterial infections.Item Enhanced viral inactivation by photodynamic therapy using curcumin and methylene blue: an in vitro study with bacteriophage as a viral mode(The Royal Society of Chemistry) Miñán, Alejandro Guillermo; Inada, Natalia Mayumi; Ferreira-Strixino, Juliana; Martins, Layla Farage; Silva, Aline Maria da; Bagnato, Vanderlei SalvadorThe global spread of SARS-CoV-2 highlighted the urgent need for broad-spectrum antiviral strategies. One promising approach is antimicrobial photodynamic therapy (aPDT), which, in the presence of oxygen, suitable photosensitizers and irradiation, generates reactive oxygen species capable of inactivating a broad spectrum of viruses. In this work, in vitro aPDT assays were performed using curcumin (Cur) and methylene blue (MB) as biocompatible photosensitizers, with bacteriophage ZC01 serving as the viral model and irradiation at 450 nm and 660 nm. Bacteriophages are frequently used as robust viral models due to their structural tolerance to photodynamic treatments compared with many mammalian viruses. Under the experimental conditions employed, a high viral load (B109 PFU mL-1) was used to represent a challenging inactivation scenario. The combination of curcumin and methylene blue at fluences of 12.5 and 25 J cm-2 per wavelength produced viral load reductions of 7.01log10 and 9.14log10, respectively. These results indicate that Cur/MB combination can achieve efficient photodynamic viral inactivation under moderate irradiation fluences. This in vitro platform may contribute to the development of photodynamic antiviral strategies and provides a practical system for evaluating potential photosensitizers and irradiation conditions for viral photoinactivation.