Publications

Abstract Aim This study investigates the mechanisms of action of a promising series of previously synthesized quaternary ammonium (QASs) and phosphonium (QPSs) salts, which have shown potent activity against Staphylococcus aureus, including methicillin-resistant strains (MRSA).Methods and results The effects of QASs and QPSs on S. aureus surface charge, total surface hydrophobicity, intracellular potassium release, membrane integrity, and ultrastructure were examined. QASs and QPSs significantly altered bacterial surface properties by reducing negative surface charge, disrupting membrane integrity, and inducing potassium leakage and propidium iodide uptake. Furthermore, S. aureus became less hydrophilic due to changes in surface hydrophobicity. Transmission electron microscopy revealed cytoplasmic leakage and the presence of electron-dense extracellular material around damaged bacterial cells upon exposure to high concentrations of these salts.Conclusions The antimicrobial activity of QASs and QPSs is driven by their ability to alter bacterial surface properties, destabilizing and disrupting membranes.

Abstract Herein we report a visible-light-active photocatalytic nanocomposite (NC50:50) prepared from carbon dots (CDs) and TiO2 nanoparticles, which was applied to the photodegradation of organic dyes in water. The CDs incorporated corn stover, a major agricultural waste, and were prepared via hydrothermal treatment. Using a visible- light irradiation source and the dye methylene blue as a representative of the organic dyes class, we observed that a 374 % enhancement of the catalytic performance was achieved by adding CDs relative to bare TiO2. This was possible due to increased visible-light absorption and better photonic efficiency. Tests using reactive species scavengers indicated that three active species (superoxide anion, hydroxyl radicals, and electrons) were responsible for the photodegradation process, differing from bare TiO2 in which only the hydroxyl radical has a relevant role. Photocatalytic degradation was also observed toward Rhodamine B, Orange II and Methyl Orange. Finally, we performed a life cycle assessment (LCA) study to assess and analyse the associated environmental impacts of NC50:50 compared with other alternatives, which revealed that NC50:50 is the alternative resulting in the least environmental impacts. In summary, NC50:50 could, under visible-light irradiation, efficiently remove different organic dyes while incorporating organic waste materials and reducing the impacts associated with their use. We expect that this study provides a base for a more environmentally sustainable design of visible- light-active photocatalysts via waste upcycling.

Abstract This study investigates the structural and transport properties of SDS, CTAB, and SB3-12 micelles in three deep eutectic solvents (DESs), Ethaline, Glyceline, and Reline, using molecular dynamics (MD) simulations. The influence of solvent composition on micelle morphology, interactions, and dynamics was explored, revealing key differences driven by the DES environment. Structural analyses, including eccentricity and radius of gyration, demonstrated that micelle shape and compactness vary significantly depending on the solvent. In Ethaline and Reline, larger micelles showed significant deviations from spherical shapes, while micelles in Glyceline became more spherical and compact, particularly those formed by SB3-12. Radial distribution functions highlighted different levels of micelle-solvent interactions, with SDS showing strong interactions with HBD components and SB3-12 exhibiting prominent self-interaction. According to hydrogen bonding analysis, micelles slightly disrupt the DES hydrogen bond network, with SB3-12 establishing the most significant hydrogen bond connections. The transport property analysis revealed that larger micelles have lower diffusion coefficients, whereas smaller micelles enhance DESs' component mobility. These findings advance the understanding of micelle behavior in DESs and also help in the optimization of DES-surfactant systems for applications such as electrodeposition, nanomaterial templating, and drug delivery. Future research will focus on surfactant interactions with surfaces to further improve these applications.

Abstract Active and abandoned mining sites are significant sources of heavy metals and metalloid pollution, leading to serious environmental issues. This study assessed the environmental risks posed by potentially toxic elements (PTEs), specifically arsenic (As) and antimony (Sb), in the Technosols (mining residues) of the former Pej & atilde;o coal mine complex in Northern Portugal, a site impacted by forest wildfires in October 2017 that triggered underground combustion within the waste heaps. Our methodology involved determining the pseudo-total concentrations of As and Sb in the collected heap samples using microwave digestion with aqua regia (ISO 12914), followed by analysis using hydride generation-atomic absorption spectroscopy (HG-AAS). The concentrations of As an Sb ranging from 31.0 to 68.6 mg kg-1 and 4.8 to 8.3 mg kg-1, respectively, were found to be above the European background values reported in project FOREGS (11.6 mg kg-1 for As and 1.04 mg kg-1 for Sb) and Portuguese Environment Agency (APA) reference values for agricultural soils (11 mg kg-1 for As and 7.5 mg kg-1 for Sb), indicating significant enrichment of these PTEs. Based on average Igeo values, As contamination overall was classified as unpolluted to moderately polluted while Sb contamination was classified as moderately polluted in the waste pile samples and unpolluted to moderately polluted in the downhill soil samples. However, total PTE content alone is insufficient for a comprehensive environmental risk assessment. Therefore, further studies on As and Sb fractionation and speciation were conducted using the Shiowatana sequential extraction procedure (SEP). The results showed that As and Sb levels in the more mobile fractions were not significant. This suggests that the enrichment in the burned (BCW) and unburned (UCW) coal waste areas of the mine is likely due to the stockpiling of lithic fragments, primarily coals hosting arsenian pyrites and stibnite which largely traps these elements within its crystalline structure. The observed enrichment in downhill soils (DS) is attributed to mechanical weathering, rock fragment erosion, and transport processes. Given the strong association of these elements with solid phases, the risk of leaching into surface waters and aquifers is considered low. This work underscores the importance of a holistic approach to environmental risk assessment at former mining sites, contributing to the development of sustainable remediation strategies for long-term environmental protection.

Abstract (1) Background: The under-representation of women in STEM fields, particularly in areas such as physics and computing, is far from being resolved. This gender gap has complex causes. This research was carried out to understanding how physics teachers in Portugal are aware of the existence of a gender gap and how they use or are willing to use girl-friendly strategies in their lessons; (2) Methods: A sample of 55 Portuguese physics and chemistry teachers from the third cycle of basic education and secondary education and an 8-item survey were used. (3) Results: The results show that most teachers perceive girls' participation in physics as satisfactory, and that girls do not perceive a gender gap and are interested in the subject, but may not be aware of the concept and application of girl-friendly strategies. (4) Conclusions: No correlation was found between gender or years of service and interest in the topic of girl-friendly strategies. Further research with a more diverse sample is needed to generalize these findings.

Abstract S-1 MitoPlates™ from Biolog enable the characterization of mitochondria’s function in live cells by measuring the rates of electron flow into and through the electron transport chain from different NADH or FADH2 producing metabolic substrates. This technology uses 96-well microplates pre-coated with triplicate repeats of a set of 31 substrates. Those 31 metabolic substrates have different routes of entry into the mitochondria, use different transporters, and are also oxidated by different dehydrogenases, producing reducing equivalents in the form of NADH or FADH2. The electrons produced upon oxidation of NADH or FADH2 at complex I or II, respectively, then travel to cytochrome c, where a tetrazolium redox dye (MC) can act as terminal acceptor, turning purple and absorbing at 590 nm. This mechanism allows the evaluation of cellular substrate preference by following the kinetics of MC reduction in the presence of selected substrates. In this chapter, we describe the step-by-step protocol to prepare an experiment using MitoPlate S-1 array and the OmniLog instrument to assess the metabolism of human dermal fibroblasts. We also give detailed information on how to analyze the raw data generated by the Biolog Data Analysis software to extract meaningful information and produce useful data visualizations, using reproducible methods based on a single structured dataset. © The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature 2025.

Abstract Metabolic syndrome (MetS) has been associated with disruptions in tissue mechanical homeostasis and inflammatory and metabolic derangements. However, the direct correlation between metabolic alterations and changes in tissue stiffness, and whether they could play a role as upstream initiators of disease pathology remains to be investigated. This emerging concept has yet to be put into clinical practice as many questions concerning the interplay between extracellular matrix mechanical properties and regulation of metabolic pathways remain unsolved. This review will highlight key foundational studies examining mutual regulation of cell metabolism and mechanotransduction, and opening questions lying ahead for better understanding MetS pathophysiology.

Abstract Mitochondrial dysfunction and increased reactive oxygen species (ROS) generation play an import role in different human pathologies. In this context, mitochondrial targeting of potentially protective antioxidants by their coupling to the lipophilic triphenylphosphonium cation (TPP) is widely applied. Employing a six-carbon (C6) linker, we recently demonstrated that mitochondria-targeted phenolic antioxidants derived from gallic acid (AntiOxBEN2) and caffeic acid (AntiOxCIN4) counterbalance oxidative stress in primary human skin fibroblasts by activating ROS-protective mechanisms. Here we demonstrate that C6-TPP (but not AntiOxBEN2 and AntiOxCIN4) induce cell death in human skin fibroblasts. This indicates that C6-TPP cytoxocity is counterbalanced by the antioxidant moieties of AntiOxBEN2 and AntiOxCIN4. Remarkably, C6-TPP and AntiOxBEN2 (but not AntiOxCIN4) induced a glycolytic switch, as exemplified by a reduced cellular oxygen consumption rate (OCR), increased extracellular acidification rate (ECAR), elevated extracellular lactate levels, and higher protein levels of glucose transporter 1 (GLUT-1). This switch involved activation of AMP-activated protein kinase (AMPK) and fully compensated for the loss in mitochondrial ATP production by sustaining cellular ATP content. When glycolytic switch induction was prevented ( i.e. by using a glucose-free, galactose-containing medium), AntiOxBEN2 induced cell death whereas AntiOxCIN4 did not. We conclude that, despite their similar chemical structure and antioxidant capacity, AntiOxBEN2 and AntiOxCIN4 display both common (redox-adaptive) and specific (bioenergetic-adaptive) effects.

Abstract In the last decades, major changes in ecosystems related to industrial development and environmental modifications have had a direct impact on mammalian fertility, as well as on biodiversity. It is widely demonstrated that all these changes impair reproductive function. Several studies have connected the increase of reactive oxygen species (ROS) generated in mitochondria to the recently identified decline of fertility due to various factors, including heat stress. The study of antioxidants, and especially of mitochondria targeted antioxidants, has been focused on identifying more efficient and less toxic therapies that could circumvent fertility problems. These antioxidants can be derived from natural compounds in the diet and delivered to the mitochondria in more effective forms, providing a much more natural therapy. The use of mitochondriotropic diet-based antioxidants in assisted reproductive technologies (ART) may be an important way to overcome low fertility, allowing the conservation of animal biodiversity and productivity. This paper provides a concise review of the current state of the art on this topic, with a particular focus on the antioxidants mitoquinone, AntiOxBEN2, AntiOxCIN4, urolithin A and piperine, and their effects on bovine and other animal species.