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In our previous studies, Chlorin-e6 (Ce6) demonstrated a significant reduction of microorganisms' viability against multi-species biofilm related to periodontitis while irradiated with blue light. However, the conjugation of Ce6 and antimicrobial peptides, and the incorporation of this photosensitizer in a nanocarrier, is still poorly explored. We hypothesized that chlorin-e6 conjugated to the antimicrobial peptide LL-37 loaded nanoemulsion could inhibit a multi-species biofilm related to periodontitis during photodynamic therapy (PDT), the pre-treatment with hydrogen peroxide was also tested. The nanoemulsion (NE) incorporated with Ce6 was characterized regarding the physiochemical parameters. Images were obtained by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Later, the Ce6 and LL-37 incorporated in NE was submitted to UV-Vis analysis and Reactive Oxygen Species (ROS) assay. Finally, the combined formulation (Ce6+LL-37 in nanoemulsion) was tested against multi-species biofilm related to periodontitis. The formed nanoformulation was kinetically stable, optically transparent with a relatively small droplet diameter (134.2 unloaded and 146.9 loaded), and weak light scattering. The NE system did not impact the standard UV-VIS spectra of Ce6, and the ROS production was improved while Ce6 was incorporated in the NE. The combination of Ce6 and LL-37 in NE was effective to reduce the viability of all bacteria tested. The treatment with hydrogen peroxide previous to PDT significantly impacted bacterial viability. The current aPDT regimen was the best already tested against periodontal biofilm by our research team. Our results suggest that this combined protocol must be exploited for clinical applications in localized infections such as periodontal disease. - Nanoemulsion demonstrated to be an excellent nanocarrier for photodynamic application. - Chlorin-e6 incorporated in nanoemulsion showed great physicochemical and biophotonic parameters. - The combination of chlorin-e6 and LL-37 peptide in nanoemulsion is effective to eliminate periodontal pathogenic bacteria. - The treatment with hydrogen peroxide previous to PDT significantly impacted bacterial viability., Competing Interests: Declaration of Competing Interest This manuscript has been read and approved in final form by all authors and the authors declare no conflicts of interest., (Copyright © 2023. Published by Elsevier B.V.)

The present work reports the effects of meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS 4 ) aggregation on its excited states absorption spectra, triplet states quenching by molecular oxygen and singlet oxygen production. Experimental techniques such as optical absorption, Z-scan with a white light continuum source and the Laser Flash Photolysis were used to fulfil the study. J-aggregates possess reverse saturable absorption in the 505-660 nm spectral range with a peak centered close to 540 nm. These facts together with their fast relaxation time suggest that they can be employed as material for ultrafast optical limiting and switching. Even though aggregation reduces the porphyrin excited-state lifetimes and quantum yields, it does not reduce the probability of the contact between the quencher and the excited aggregate. Aggregation does not change the contribution of energy transfer mechanisms to triplet state quenching by molecular oxygen. The production of singlet oxygen, the intense absorption in the phototherapeutic window and the high efficiency of conversion of light energy into heat, allow consider J-aggregates as a theranostic agent for photomedicine. It is proposed to use J-aggregates for diagnostics by photoacoustic images and in combination with a near-infrared photodynamic/photothermal dual mode therapy, thus improving synergistically the therapeutic response., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this manuscript, we report, the photophysical study of triplet excited states and antimicrobial photoinactivation of positively charged tetra-cisplatin porphyrin derivatives against Gram + and Gram ‒ bacterial strains. Isomeric cisplatin-porphyrins were used and applied in aPDT assays in the bacilli Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa (Gram negative) and a cocci Staphylococcus aureus (Gram positive) strains. The results show that compound substituted at meta position (3-cis-PtTPyP) is the more efficient photosensitizer against bacteria culture. In this way, tetra-cationic porphyrins containing cisplatin derivatives might be promising aPDT agents with potential applications in clinical infections., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We report on a method to study the dynamics of triplet formation based on the fluorescence signal produced by a pulse train. Basically, the pulse train acts as sequential pump-probe pulses that precisely map the excited-state dynamics in the long time scale. This allows characterizing those processes that affect the population evolution of the first excited singlet state, whose decay gives rise to the fluorescence. The technique was proven to be valuable to measure parameters of triplet formation in organic molecules. Additionally, this single beam technique has the advantages of simplicity, low noise and background-free signal detection.