Publications

Abstract <jats:p>Pollution of soils by heavy metals (HM) is a concerning result of anthropogenic activities. Iron (Fe) and silver (Ag) are HM-deemed essential and non-essential for plants and can induce toxicity when in excess. Metallothioneins (MTs) are small Cys-rich proteins involved in HM binding and oxidative stress mitigation. This study focused on Arabidopsis thaliana MTs types I, II, and III involvement in response to increasing concentrations of Fe and Ag in an organ-specific way - shoots and roots - through RT-qPCR analysis 21 days after germination, as well as biometric and biochemical assessments. The in vivo heterologous expression of AtMT2b in Nicotiana tabacum leaves was performed. Both HM reduced plant growth, with Fe accumulating dose-dependently in both shoots and roots, while Ag mainly accumulated in roots, albeit only at the highest concentration in shoots. Fe exposure caused little change in MT expression, whereas Ag strongly induced it in shoots and, to a lesser extent, in roots (particularly AtMT1a and AtMT1c). Biochemical analyses revealed distinct stress responses: Fe increased lipid peroxidation (MDA) and antioxidant compounds (GSH, thiols) mainly in shoots, while Ag triggered oxidative metabolism predominantly in shoots, with elevated HO, MDA, GSH, thiols, and proline levels. Both HM reduced photosynthetic pigments, notably -carotenes with Fe, and chlorophylls, lutein, and -carotenes with Ag. In vivo localisation showed AtMT2b to be cytosolic. Overall, Fe and Ag induced stress in A. thaliana with organ-specific responses, and MTs played a minor role in Fe tolerance but were strongly activated by Ag, especially in shoots.</jats:p>

Abstract Assisted reproductive technologies (ART) use has increased over the past decades. However, reports concerning ART's low efficiency continue to emerge, citing causes related to lower embryo quality and pregnancy rates compared to their in vivo counterparts. One of the setbacks of ART is oxidative stress, which can impair embryo developmental rates. Mitochondrial redox and energetic homeostasis determine both cell survival and death, so mitochondria are a key target for therapeutic intervention strategies. In the present work, our objective was to improve the quality of viable embryos by adding new mitochondria-targeted antioxidants in the embryo culture media to reduce oxidative stress. Two naturally derived antioxidants synthesized by our team, AntiOxBEN2 and AntiOxCIN4, based on hydroxybenzoic and hydroxycinnamic scaffolds, respectively, were studied in two different experimental protocols (here called experiments). The first experiment investigated the effects of the antioxidants on embryo development to determine their optimal concentrations. The first assay of the first experiment focused on the effects of AntiOxCIN4 at concentrations of 1, 2.5, and 10 mu M, while the second assay focused on the effects of AntiOxBEN2 at the same concentrations. A control group without supplementation was run simultaneously. The second experiment aimed to compare the best concentrations of these antioxidant molecules in the embryo culture media and their effect on embryos' resistance to vitrification/warming. In each experiment, the embryos were morphologically evaluated, and the total and viable cell numbers were examined. Reactive oxygen species (ROS) and mitochondrial polarization were also evaluated using specific fluorescent dyes. In experiment 1, an increased embryo quality was identified by using 2.5 mu M AntiOxCIN4 (p = 0.03) and 2.5 mu M AntiOxBEN2 (p = 0.001). Moreover, blastocysts supplemented with 2.5 mu M AntiOxCIN4 had higher viability (p = 0.008), while those supplemented with 2.5 mu M AntiOxBEN2 presented a greater total cell number (p = 0.01). An improvement in embryo cryosurvival following the supplementation during the culture process with either antioxidant was identified in experiment 2, with superior expansion scores after vitrification/warming and culture (2.5 mu M AntiOxCIN4, p = 0.056 and 2.5 mu M AntiOxBEN2, p = 0.059). In conclusion, both AntiOxCIN4 and AntiOxBEN2 had a beneficial effect on embryo development and cryosurvival, suggesting a potential intervention to reduce oxidative stress in assisted reproductive technologies.

Abstract Metabolic dysfunction-associated steatotic liver disease (MASLD) affects approximately 30 % of the global population. Its progression is commonly linked to excessive hepatic fat accumulation, elevated oxidative stress, and impaired mitochondrial function. Given the central role of mitochondria in cellular energy metabolism and redox balance, mitochondria-targeted bioactive molecules have emerged as a promising strategy for the prevention and treatment of MASLD. To this end, we develop AntiOxBEN<inf>2</inf>, a mitochondria-targeted compound generated by conjugating the antioxidant moiety of gallic acid with the lipophilic triphenylphosphonium cation . This design enables selective accumulation of AntiOxBEN<inf>2</inf> in the mitochondrial matrix, taking advantage of the organelle’s negative membrane potential. In multiple in vitro disease model s , AntiOxBEN<inf>2</inf> has demonstrated remarkable antioxidant properties, effectively mitigating oxidative stress and preserving mitochondrial function. However, effects on cellular and mitochondrial energy metabolism in vivo remain unexplored. In the present study, we tested whether chronic peripheral administration of AntiOxBEN<inf>2</inf> (0.5 or 2.5 mg/kg, 3x/week) could prevent MASLD development in male and female C57BL/6 J mice fed with a 30 % high-fat, 30 % high-sucrose (Western Diet, WD) diet for 16 weeks. Our results demonstrate that AntiOxBEN<inf>2</inf> treatment significantly reduced hepatic lipid accumulation in both sexes without affecting body weight. This reduction was accompanied by improvements in mitochondrial function, including enhanced fatty acid oxidation (FAO) and increased activities of mitochondrial electron transport chain (ETC) complexes. Moreover, AntiOxBEN<inf>2</inf> administration lowered circulating levels of hepatic damage markers (ALT and AST), as well as insulin and leptin. Notably, a clear sexual dimorphism was observed, with female mice displaying a more pronounced improvement in mitochondrial parameters. Collectively, these findings highlight the therapeutic potential of AntiOxBEN<inf>2</inf> for the prevention and/or treatment of MASLD. © © 2026. Published by Elsevier Masson SAS.

Abstract Pseudomonas aeruginosa biofilm-associated infections present higher recalcitrance to antimicrobial treatments, contributing to persistent and difficult-to-treat infections. Quorum sensing (QS) regulates various cellular processes that are important for the establishment and survival of microbial communities on the host. However, QS inhibitors for the treatment of P. aeruginosa biofilms remain under-researched, partly due to the complexity of QS signalling pathways and the challenge of developing non-toxic inhibitors. Herein, the bioactivity of 2-{(2E)-2-[1-(pyridin-2-yl)ethylidene]hydrazinyl}-1,3-thiazole-4-carboxylic acid (TTNF37), a novel pyridine-based thiazolyl-hydrazone (PTH), was investigated. The compound antimicrobial activity was evaluated against a broad spectrum of microorganisms, its antioxidant potential was assessed using different assays, and its QS-inhibitory effect on P. aeruginosa was studied using bioreporter strains. The effect on P. aeruginosa biofilm formation was analysed in terms of biomass, culturability, and metabolic activity, structure, and cell membrane integrity, while virulence factors were evaluated through absorbance measurements. In addition, molecular docking studies were performed to predict the drug's interactions with essential QS proteins and biological targets. TTNF37 exhibited potent antimicrobial activity with low to moderate minimum inhibitory concentrations against clinically relevant Gram-negative and Gram-positive bacteria, as well as fungi and yeasts. It also showed antioxidant activity, with variable effectiveness across different radicals and systems. TTNF37 inhibited the 3-oxo-C12-HSL-dependent QS system of P. aeruginosa in a dose-dependent manner, with reductions ranging from 26% to 98%. It also impaired the production and detection of 3-oxo-C12-HSL, resulting in a 56% and 65% decrease in bioluminescence, respectively. Molecular docking studies revealed strong binding interactions with LasI and LasR proteins, with affinity values exceeding those of furvina, a known potent QS inhibitor. Molecular dynamics simulations validated stable TTNF37 binding to LasR and LasI. Both experimental and docking data indicate a significant interaction with human serum albumin (HSA). TTNF37 also significantly reduced pyocyanin production and prevented biofilm set-up with a reduction of 50% in biomass with pronounced alterations in biofilm structure. These results indicate the potential of TTNF37 and related PTHs for treating biofilm-associated infections.

Abstract The ability to assess molecular binding kinetics in real time is critical for advancing our understanding of molecular interactions in biochemical and biotechnological systems. This work presents a novel optical tweezer (OT)-based method to monitor molecular affinity in real time, focusing on the high-affinity streptavidin-biotin system as a model. Transparent poly(methyl methacrylate) (PMMA) microparticles functionalized with streptavidin were trapped before, during, and after binding with biotinylated bovine serum albumin (biotin-BSA), enabling the analysis of forward-scattered signals to detect nanoscale changes in particle size. By applying the Power Spectral Density method, the friction coefficient of individual particles was calculated, allowing for real-time tracking of binding dynamics and the estimation of the association rate constant (kon approximate to 106M-1s-1). These results are consistent with literature values and demonstrate the potential of this OT-based approach for non-invasive, label-free detection of molecular interactions. Compared to existing techniques, such as atomic force microscopy and cantilever-based sensors, this method offers significant advantages, including real-time monitoring, adaptability to different bioaffinity systems, and compatibility with miniaturized setups. This work establishes a foundation for using OT-based tools to monitor high-affinity molecular interactions in real time. While demonstrated here using biotinylated BSA as a model ligand, future studies will explore the method's applicability to smaller ligands and more subtle surface modifications.

Abstract Diabetic foot ulcers (DFUs) represent a significant global burden, associated with high morbidity and increased mortality. More than half of DFUs become infected by polymicrobial communities, in which Pseudomonas aeruginosa and Staphylococcus aureus form resilient biofilms. Antimicrobial photodynamic inactivation (aPDI) using blue light is promising, its efficacy against polymicrobial biofilms remains suboptimal in infected DFUs. This study evaluated, for the first time, the activity of a berberine-gentamicin (Ber-Gen) combination under blue light photoactivation against dual-species P. aeruginosa MJMC568-A and S. aureus MJMC568-B biofilms, both isolated from a DFU patient. First, the minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) for each agent against pre-formed dual-species biofilms were determined. Ber and Gen alone did not reach MBIC or MBEC at concentrations <2000 & micro;g mL(-1), but in combination, MBIC values decreased two-fold to 1000 & micro;g mL(-1) for Ber and 1024 & micro;g mL(-1) for Gen. The combinatorial effect was assessed by checkerboard (CKB), with Ber-Gen resulting in a synergistic effect for MBIC values. The optimised concentrations from CKB were tested under one, two, and three irradiation cycles (with a 24 h interval between irradiation cycles) of blue light at 30 mW cm(-2) for 10 min per cycle (18 J cm(-2)). Antibiofilm activity was quantitatively assessed by biomass (crystal violet), metabolic activity (alamar blue), and culturability (colony-forming unit (CFU cm(-2)) counts). Photoactivated Ber-Gen produced strong reductions in biomass, metabolic activity, and culturability after one cycle (approximate to 50%, approximate to 70%, and approximate to 5 log CFU cm(-2), respectively), near-complete eradication after two cycles (approximate to 60%, approximate to 80%, and approximate to 6 log CFU cm(-2), respectively), and a further effect after three cycles (approximate to 90%, approximate to 95%, and approximate to 10 log CFU cm(-2), respectively). Regrowth assays showed full recovery after one cycle, about half recovery after two, and less than 10% recovery after three cycles. Mechanistic assays on the antibiofilm effect included measurement of reactive oxygen species (ROS) by fluorometry, membrane integrity by flow cytometry and confocal microscopy, matrix components by confocal microscopy, spectrophotometric and fluorometric assays, and architecture by optical coherence tomography. Biofilm structure was markedly disrupted, with strong reductions in thickness, extracellular matrix components such as proteins, polysaccharides, and eDNA. These structural changes coincided with a decrease in biofilm cells' membrane integrity and increased ROS production. Overall, Ber-Gen-mediated blue light aPDI exhibits strong activity against dual-species biofilms of P. aeruginosa and S. aureus.

Abstract <jats:title>Abstract</jats:title> <jats:sec> <jats:title>Aims</jats:title> <jats:p>Antimicrobial resistance, particularly in healthcare-associated infections (HAIs), highlights the need for more effective and sustainable disinfection strategies. This study evaluated the bactericidal effects of two conventional biocides—benzalkonium chloride (BAC) and peracetic acid (PAA)—and two phytochemicals—salicylic acid (SAL) and eugenol (EUG)—against Escherichia coli and Staphylococcus aureus, focusing on potential synergistic interactions.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods and Results</jats:title> <jats:p>Antimicrobial efficacy was assessed through standardized dose- and time-response assays (EN 1276) and kinetic modeling using the Chick–Watson and Weibull equations. BAC and PAA achieved complete bacterial inactivation at 3 mg/L and 1 mg/L, respectively, within 5–15 minutes, confirming rapid and potent activity. Conversely, SAL and EUG required substantially higher concentrations (500–1700 mg/L) to achieve total loss of culturability. Chick–Watson modelling demonstrated high disinfection rate coefficients for BAC and PAA, while SAL and EUG exhibited markedly lower values. Synergy testing revealed a strong interaction between BAC and EUG, with fractional bactericidal concentration indices of 0.350 for E. coli and 0.309 for S. aureus, whereas other combinations were additive. Weibull modelling further indicated that bacterial tolerance was dependent on compound type and concentration, with S. aureus generally more susceptible than E. coli.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>These findings collectively confirm the enhanced efficacy of selected biocide/phytochemical combinations, allowing lower concentrations and promoting more sustainable antimicrobial practices.</jats:p> </jats:sec>

Abstract The high costs of equipment and maintenance for Chemistry laboratories are a barrier to quality education in this science. However, the emergence of user-friendly and low-cost technological tools helps to mitigate this problem. This paper presents a STEM proposal for exploring distillation collaboratively in a remote laboratory with live data transmission and sharing online. The approach was analyzed by four teachers from Mozambique who, in that context, highlighted the positive potential for knowledge exchange between schools and cultures and the negative lack of technological means in schools for its implementation. They recognize great potential for implementation in higher education, as institutions have better resources. Thus, richer learning experiences can be promoted for all participants.

Abstract Student-centred learning requires a variety of approaches, such as inquiry-based learning and the tackling of authentic and problem-based learning activities, to make the teaching and learning process more meaningful and to encourage students to participate more actively in class. The inquiry approach enables students to investigate solutions to real problems, awakening their need to ask questions, design and conduct research, collect and analyse data, interpret results and present them in a structured way. This study investigates the influence of an inquiry-based science education (IBSE) module on the development of oral and written communication skills among 10th grade students. The study is set in a secondary school context and focuses on a problem-based learning approach centred around gases and dispersions. A total of 111 students participated in this one-group post-assessment qualitative study, where evaluation rubrics were applied to assess students' written and oral communication, focusing on correctness, clarity and mastery of scientific language. The results showed that the majority of students performed well in both written and oral tasks, demonstrating improved scientific communication skills. This suggests that IBSE, particularly in the context of secondary education, can be an effective approach to fostering students' abilities to communicate scientific concepts. The study has implications for enhancing pedagogical practices and encourages further research on the long-term effects of IBSE on student learning.

Abstract An acid-base titrator connected to the Internet was developed for conducting remote investigative experiments. The experiment was broadcasted in a high school senior classroom, with the presence of a facilitating teacher. The activity required students to determine the indicator present in the solution. To carry out the activity, students added acid or base to sweep the pH range from 0 to 14 and noted the corresponding coloration to the pH through video analysis. The results obtained were very satisfactory, both in the identification of the indicator and in the acceptance and engagement of the students in the activity.