Gelatin nanoparticles have recently been receiving considerable attention because they offer a good option as release systems due to their low cost, biocompatibility, biodegradability and its application in several types of formulations. This study aim was to evaluate the potential application of gelatin nanoparticles entrapping a photosensitizer in Photodynamic Therapy. Gelatin nanoparticles were studied by steady-state techniques and the biological activity evaluated by in vitro MTT assay. The particles were spherical in shape exhibiting a 273 nm diameter with a low tendency to aggregate. The loading efficiency was 76%. Photosensitizer photophysical properties were shown to be preserved after GN encapsulation. The cells viability obtaining 85% cells death compared with control. The results demonstrate that gelatin nanoparticles can be successfully applied for photosensitizers encapsulation or other active drugs and be used as an optimal medium for a variety of bioactive materials, which can also be encapsulated by the proposed method.

Staphylococcus aureus are multiresistant pathogens that causes superficial and systemic infections. Antimicrobial photodynamic therapy (APDT) is an alternative in the treatment of diseases caused b...

Antimicrobial photodynamic therapy (aPDT) is considered a promising alternative strategy to control Acinetobacter baumannii infections. In this study, we evaluated the action of aPDT mediated by a new photosensitizer derivative from chlorin e-6 (Fotoenticine—FTC) on A. baumannii, comparing its effects with methylene blue (MB). For this, aPDT was applied on A. baumannii in planktonic growth, biofilms, and burn infections in Galleria mellonella. The absorption of FTC and MB by bacterial cells was also evaluated using microscopic and spectrophotometric analysis. The results of planktonic cultures showed that aPDT reduced the number of viable cells compared to the non-treated group for the reference and multidrug-resistant A. baumannii strains. These reductions varied from 1.4 to 2 log₁₀ CFU for FTC and from 2 log₁₀ CFU to total inhibition for MB. In biofilms, aPDT with MB reduced 3.9 log₁₀ CFU of A. baumannii, whereas FTC had no effect on the cell counts. In G. mellonella, only MB-mediated aPDT had antimicrobial activity on burn injuries, increasing the larvae survival by 35%. Both photosensitizers were internalized by bacterial cells, but MB showed a higher absorption compared to FTC. In conclusion, MB had greater efficacy than FTC as a photosensitizer in aPDT against A. baumannii.