Browsing by Author "Faustino, M. Amparo F."
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- Deep Eutectic Solvents as alternative solvents in Antimicrobial Photodynamic TherapyPublication . Vieira, Cátia; Bartolomeu, Maria; Pedro, Sónia N.; Gomes, Ana T. P. C.; Dias, Cristina J.; Gamelas, Sara R. D.; Lourenço, Leandro M. O.; Freire, Carmen S. R.; Neves, M. Graça P. M. S.; Faustino, M. Amparo F.; Almeida, Adelaide
- Disinfection of wastewater in the mitigation of SARS-CoV-2 by photodynamic treatmentPublication . Almeida, Adelaide; Gomes, Marta; Bartolomeu, Maria; Vieira, Cátia; Gomes, Ana T. P. C.; Faustino, M. Amparo F.; Neves, M. Graça P. M. S.
- Investigation of the potential of deep eutectic solvents (DES) as alternative solvents in antimicrobial photodynamic therapyPublication . Vieira, Cátia; Bartolomeu, Maria; Pedro, Sónia N.; Gomes, Ana T. P. C.; Dias, Cristina J.; Gamelas, Sara R. D.; Lourenço, Leandro M. O.; Freire, Carmen S. R.; Neves, M. Graça P. M. S.; Faustino, M. Amparo F.; Almeida, AdelaideAntimicrobial Photodynamic Therapy (aPDT) is gaining recognition as an effective approach for the photoinactivation of a broad spectrum of microorganisms [1,2]. Due to their apolar behavior, photosensitizers (PS) often have low solubility in aqueous media requiring the use of toxic organic solvents that are incompatible with their application in the field [4]. In this study, the potential of Deep Eutectic Solvents (DES) to prepare formulations of one chlorin (bearing five cationic charges) and two porphyrins (neutral THPP, and tetra cationic Tetra-Py(+)-Me) poorly water-soluble was investigated. To this purpose, formulations of each PS were prepared in DMSO and three DES (betaine:glycerol, proline:xylitol and betaine:citric acid) and their physio-chemical properties, cytotoxicity for mammalian cells, and photodynamic action towards Escherichia coli, as a gramnegative bacterium model, were evaluated. The physico-chemical experiments revealed that all PS were soluble in the selected DES. However, PS stability varied highly depending on the solvent used. In dark conditions, chlorin remained stable in DES formulations while strong aggregation was observed in DMSO. In contrast, THPP showed better stability in the former solvent. Tetra-cationic porphyrin was stable in the dark regardless of the solvent used, but upon irradiation, DES formulations increased this PS photostability. Regarding the biological experiments, betaine:glycerol and proline:xylitol formulations lacked toxicity towards mammalian cells and improved Tetra-Py(+)Me photodynamic activity against E. coli. On the other hand, betaine:citric acid formulation, although highly toxic to Vero cells, enhanced the photodynamic action of both THPP and Tetra-Py(+)-Me. Overall, these findings indicate that DES have a high potential to prepare formulations of PS with low solubility in aqueous solutions and, in some cases, can improve their antimicrobial photodynamic activity.
- A study of wastewater disinfection with photodynamic treatment and its ecotoxicological effectsPublication . Bartolomeu, Maria; Gomes, Thierry; Campos, Fábio; Loureiro, Susana; Neves, M. Graça P. M. S.; Faustino, M. Amparo F.; Gomes, Ana T. P. C.; Almeida, AdelaideViruses have higher mutation rates when compared with other microorganisms, particularly RNA viruses [1]. The higher mutation rate promotes the development of resistance to traditional antivirals, establishing a resistance behavior in viruses populations [1]. RNA viruses in wastewater (WW) have already been reported, leading to potential public health risks [2]. Wastewater treated with conventional antimicrobial approaches (tertiary WW treatments) like UV light, chlorine, and ozone can lead to viruses mutations and the formation of toxic by-products harmful to humans and the environment [3]. All this, highlights the inevitability to provide alternative WW disinfection techniques. Antimicrobial Photodynamic treatment (PDt), an approach based on the action of reactive oxygen species (ROS), is being considered a promising alternative to viruses inactivation without the generation of viral mutations or toxic by-products [4,5]. This study evaluated the efficiency of PDt in the inactivation of bacteriophage Phi6 (RNA-viruses model) in real WW. PDt assays were carried out in a buffer solution (PBS, as a controlled medium) and in WW (after secondary treatment) with Methylene Blue (MB) as photosensitizer (PS), and a low energy consuming light source (LED). The disinfection protocol developed with MB resulted in an efficient inactivation of the bacteriophage Phi6, both in PBS and in the real WW. Considering that treated effluents are released into the environment, the acute toxicity of PDttreated WW to the model organism Daphnia magna was also evaluated during a 48h exposure to the PDt-treated WW with MB. In this communication it will be present and discuss the PDt protocol developed to photoinactivate the model RNAvirus bacteriophage Phi6 and the preliminary results of the acute toxicity of PDt-treated WW in Daphnia magna model.
- A study of wastewater disinfection with photodynamic treatment and its ecotoxicological effectsPublication . Bartolomeu, Maria; Gomes, Thierry; Campos, Fábio; Loureiro, Susana; Neves, M. Graça P. M. S.; Faustino, M. Amparo F.; Gomes, Ana T. P. C.; Almeida, Adelaide
- Wastewater disinfection with photodynamic treatment and evaluation of its ecotoxicological effectsPublication . Bartolomeu, Maria; Gomes, Thierry J.; Campos, Fábio; Vieira, Cátia; Loureiro, Susana; Neves, M. Graça P. M. S.; Faustino, M. Amparo F.; Gomes, Ana T. P. C.; Almeida, AdelaideResearch has demonstrated the presence of viruses in wastewater (WW), which can remain viable for a long period, posing potential health risks. Conventional WW treatment methods involving UV light, chlorine and ozone efficiently reduce microbial concentrations, however, they produce hazardous byproducts and microbial resistance that are detrimental to human health and the ecosystem. Hence, there is a need for novel disinfection techniques. Antimicrobial Photodynamic Inactivation (PDI) emerges as a promising strategy, utilizing photosensitizers (PS), light, and dioxygen to inactivate viruses. This study aims to assess the efficacy of PDI by testing methylene blue (MB) and the cationic porphyrin TMPyP as PSs, along a low energy consuming white light source (LED) at an irradiance of 50 mW/cm2, for the inactivation of bacteriophage Phi6. Phi6 serves as an enveloped RNA-viruses surrogate model in WW. PDI experiments were conducted in a buffer solution (PBS) and real WW matrices (filtered and non-filtered). Considering the environmental release of the treated effluents, this research also evaluated the ecotoxicity of the resulting solution (post-PDI treatment effluent) on the model organism Daphnia magna, following the Organisation for Economic Cooperation and Development (OECD) immobilization technical 202 guideline. Daphnids were exposed to WW containing the tested PS at different concentrations and dilutions (accounting for the dilution factor during WW release into receiving waters) over 48 h. The results indicate that PDI with MB efficiently inactivated the model virus in the different aqueous matrices, achieving reductions superior to 8 log10 PFU/mL, after treatments of 5 min in PBS and of ca. 90 min in WW. Daphnids survival increased when subjected to the PDI-treated WW with MB, considering the dilution factor. Overall, the effectiveness of PDI in eliminating viruses in WW, the fading of the toxic effects on daphnids after MB’ irradiation and the rapid dilution effect upon WW release in the environment highlight the possibility of using MB in WW PDI-disinfection.