Browsing by Author "Gamelas, Sara R. D."
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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
- Enhancing bacterial photodynamic inactivation through combined action of potassium iodide and cationic phthalocyaninesPublication . Gamelas, Sara R. D.; Bartolomeu, Maria; Vieira, Cátia; Faustino, Maria A. F.; Tomé, João P. C.; Tomé, Augusto C.; Almeida, Adelaide; Lourenço, Leandro M. O.Infectious diseases remain a leading cause of death all around the world. Over the last three decades, the alarming and escalating emergence of antibiotic-resistant bacterial strains has caused some concern among the scientific community [1,2]. Photodynamic inactivation (PDI) emerges as an alternative for inactivating microorganisms, including bacteria [1–3]. The use of phthalocyanine (Pc) derivatives as photosensitizers (PS) in PDI has already proven effectiveness against various microorganisms [4]. Moreover, the addition of KI as a coadjutant can, in certain circumstances, enhance the efficiency of neutral, negative, and positively charged PS against Gram-negative and Gram-positive bacteria [2,4]. In this study will be demonstrated the effect of KI in PDI of E. coli and S. aureus with cationic Pcs bearing tris(trimethylammoniummethyl) or pyridinium-pyrazolyl groups.
- 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.
- Photodynamic inactivation of a RNA-virus model using water-soluble β-octa-Substituted pyridinium-pyrazolyl phthalocyaninesPublication . Gamelas, Sara R. D.; Bartolomeu, Maria; Gomes, Thierry J.; Faustino, Maria A.F.; Tomé, João P.C.; Tomé, Augusto C.; Almeida, Adelaide; Gomes, Ana T. P. C.; Lourenço, Leandro M. O.Among the various groups of microorganisms, viruses have generally a greater capacity for mutation, especially RNA viruses, as was demonstrated by SARS-CoV2 virus mutations. This high mutation rate promotes the development of their resistance to traditional antivirals and establishes the resistance behaviour in virus populations, decreasing their susceptibility to these drugs. In this context, the photodynamic treatment appears as a potentially effective method against microorganisms and, considering its mode of action is not likely to lead to the development of resistance. In this work, two newly zinc(II) phthalocyanines (ZnPcs) bearing pyridinium-pyrazolyl groups (2a and 3a) were synthesized, characterized, and applied in photodynamic inactivation (PDI) of bacteriophage Φ6 (or Phage Phi6) as a RNA-virus model. These quaternized dyes were applied at different concentrations (from 5.0 to 20 μM, and under white light irradiation in the irradiance range between 50 and 150 mW/cm2) to test their efficiency for possible clinical or environmental applications. The results showed that the new cationic ZnPcs 2a and 3a efficiently inactivate the RNA-virus model (bacteriophage Φ6), even at the lowest tested irradiance. These compounds are thus promising photosensitizers to be used in various contexts.