Publications

Abstract Antibacterial resistance poses a critical public health threat, challenging the prevention and treatment of bacterial infections. The search for innovative antibacterial agents has spurred significant interest in quaternary heteronium salts (QHSs), such as quaternary ammonium and phosphonium compounds as potential candidates. In this study, a library of 49 structurally related QHSs was synthesized, varying the cation type and alkyl chain length. Their antibacterial activities against Staphylococcus aureus, including antibiotic-resistant strains, were evaluated by determining minimum inhibitory/bactericidal concentrations (MIC/MBC) <= 64 mu g/mL. Structure-activity relationship analyses highlighted alkyl-triphenylphosphonium and alkyl-methylimidazolium salts as the most effective against S. aureus CECT 976. The length of the alkyl side chain significantly influenced the antibacterial activity, with optimal chain lengths observed between C-10 and C-14. Dose-response relationships were assessed for selected QHSs, showing dose-dependent antibacterial activity following a non-linear pattern. Survival curves indicated effective eradication of S. aureus CECT 976 by QHSs at low concentrations, particularly compounds 1e, 3e, and 5e. Moreover, in vitro human cellular data indicated that compounds 2e, 4e, and 5e showed favourable safety profiles at concentrations <= 2 mu g/mL. These findings highlight the potential of these QHSs as effective agents against susceptible and resistant bacterial strains, providing valuable insights for the rational design of bioactive QHSs.

Abstract Carbon electrodes are widely accepted as very versatile platforms, with applications ranging from electrocatalysis to sensors and other devices, like fuel cells and water electrolyzers. However, there are still difficulties given that over time, at high potentials, the oxidation of carbon materials (as a catalyst and/or catalyst support) can play a detrimental role, undermining the efficiency and stability of the electrochemical processes and devices performance. In this paper, it is reported the research work followed by resourcing to electrochemical analytical techniques, like cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), along with complementary atomic force microscopy (AFM) and water contact angle (WCA) measurements. These techniques were used to characterise glass-type and paper-based carbon electrodes. On a nature-inspired solution, we took advantage of the different interfacial carbon-support hierarchical porous structures to boost the carbon electrocatalytic effect towards sensing the ferri/ferrocyanide redox couple ([Fe(CN)6]3-/4−) in aqueous solution. It is shown that the best results were achieved with carbon paper electrodes without wet proofing, given its hierarchical porous structure and absence of the insulating binder. This research endeavors to contribute to the ongoing advancements in the field of electrochemical green energy conversion by exploring innovative approaches and materials, with the ultimate aim of developing carbon substrates that not only enhance performance but also promote environmental sustainability. © 2024

Abstract Lupine is a legume commonly used in human diet as a functional food due to its high nutritional content and important technological properties. However, its consumption can lead to the manifestation of adverse immunological reactions, posing significant health issues in sensitized/allergic patients. This work aims to investigate the effect of food processing combined with simulated gastrointestinal (GI) digestion on the immunoreactivity of lupine gamma-conglutin. Model foods of wheat pasta containing 35% of lupine flour (Lupinus albus, L. luteus, and L. angustifolius) were prepared and submitted to a boiling process. The proteins were extracted and their profiles characterized by SDS-PAGE. Simulated GI digestion was performed on thermally treated pasta using the INFOGEST harmonized digestion protocol 2.0. The IgG binding capacity of gamma-conglutin was assessed by immunoblotting in non-reducing conditions and indirect ELISA with specific antibodies. Results demonstrate that the boiling treatment affected the immunoreactivity of the three lupine species differently. Simulated GI digestion led to extensive destruction of the protein structure, more significant in the intestinal phase, reducing but not abolishing the IgG affinity to gamma-conglutin and its potential presentation to immunocompetent cells. This information can offer valuable insights to the food industry for developing food formulations with reduced allergenic properties.

Abstract The increase of bacterial resistance to antibiotics is a growing concern worldwide and the search for new therapies could cost billions of dollars and countless lives. Inert surfaces are major sources of contamination due to easier adhesion and formation of bacterial biofilms, hindering the disinfection process. Therefore, the objective of this study was to develop a photoactivatable and anti-adhesive kappa-carrageenan coating using proanthocyanidin as a photosensitizer. The complete reduction (>5-log(10) CFU/cm(3)) of culturable cells of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa pathogens was achieved after 30 min of exposure to visible light (420 nm; 30 mW/cm(2)) with 5 % (w/v) of the photosensitizer. Cell membrane damage was confirmed by measuring potassium leakage, epifluorescence microscopy and bacterial motility analysis. Overall, visible light irradiation on coated solid surfaces mediated by proanthocyanidin showed no cytotoxicity and inactivated clinically important pathogens through the generation of reactive oxygen species, inhibiting bacterial initial adhesion. The developed coating is a promising alternative for a wide range of applications related to surface disinfection and food biopreservation.

Abstract Biosensors, especially those designed for detecting food allergens like Gly m TI in soybean, play a crucial role in safeguarding individuals who suffer from adverse food allergies, extending to both individual well-being and broader public health considerations. Furthermore, their integration into food production and monitoring processes aids in compliance with regulatory standards, reducing the incidence of allergen-related recalls and protecting vulnerable populations. Technological advancements in biosensor development, such as increased portability, real-time monitoring capabilities, and user-friendly interfaces, have expanded their practical applications, making them indispensable in various settings, including manufacturing plants, food service establishments, and even at-home use by consumers. For the first time, a biosensor targeting the Gly m TI allergen based on molecularly imprinted polymer (MIP) technology was developed to detect/quantify soybean in complex food matrices and effectively address the detection challenges of complex and processed foods. The Gly m TI-MIP underwent a thorough validation process using anti-Gly m TI IgG raised as a polyclonal response to the trypsin inhibitor. Gly m TI-MIP was successfully tested across a range of food matrices, including tree nuts (e.g., peanuts, walnuts, and hazelnuts) and legumes (e.g., lentils, beans, and lupine), presenting minimal cross-reactivity with lupine and walnut. The innovative approach provided a linear response in the 1 ag mL(-1) - 10 mu g mL(-1) range, with a LOD<1 ag mL(-1). Applying the Gly m TI-MIP sensor to complex model foods allowed to detect 0.1 mg kg(-1) (0.00001 %) of soybean protein isolate in biscuits, ham, and sausages before and after the respective thermal treatments. The innovative biosensor can significantly improve food safety protocols by addressing the complexities of tracing allergens in processed and unprocessed food products. By ensuring rigorous allergen control, these biosensors may support global food trade compliance with international safety standards, boost consumer confidence, and promote transparency in food labeling, ultimately contributing to a safer food supply chain.

Abstract Determining the origin and pathways of contaminants in the natural environment is key to informing any mitigation process. The mass magnetic susceptibility of soils allows a rapid method to measure the concentration of magnetic minerals, derived from anthropogenic activities such as mining or industrial processes, i.e., smelting metals (technogenic origin), or from the local bedrock (of geogenic origin). This is especially effective when combined with rapid geochemical analyses of soils. The use of multivariate analysis (MVA) elucidates complex multiple-component relationships between soil geochemistry and magnetic susceptibility. In the case of soil mining sites, X-ray fluorescence (XRF) spectroscopic data of soils contaminated by mine waste shows statistically significant relationships between magnetic susceptibility and some base metal species (e.g., Fe, Pb, Zn, etc.). Here, we show how qualitative and quantitative MVA methodologies can be used to assess soil contamination pathways using mass magnetic susceptibility and XRF spectra of soils near abandoned coal and W/Sn mines (NW Portugal). Principal component analysis (PCA) showed how the first two primary components (PC-1 + PC-2) explained 94% of the sample variability, grouped them according to their geochemistry and magnetic susceptibility in to geogenic and technogenic groups. Regression analyses showed a strong positive correlation (R-2 > 0.95) between soil geochemistry and magnetic properties at the local scale. These parameters provided an insight into the multi-element variables that control magnetic susceptibility and indicated the possibility of efficient assessment of potentially contaminated sites through mass-specific soil magnetism.

Abstract The incidence of skin cancer is rising globally. Hydrogels are among the most extensively studied systems in the plight to combat this disease due to their unique features—such as versatility, biocompatibility, capacity for stimuli-responsiveness, common non-invasiveness, photodynamic therapy capability, and ability to contain smaller delivery structures embedded—and their potential for continuous enhancement. Herein, we review the major strategies and findings concerning the development of hydrogel-based colloidal systems for skin cancer treatment, dividing the literature into three main areas: hydrogels as direct drug delivery systems; hydrogels as scaffolds for drug-loaded nanostructures and sensitizers; and hydrogels in the form of nanogels. Hydrogels have been employed as slow-release drug reservoirs, which can be administered topically or injected directly into the tumor mass, yielding potent anticancer effects. Hydrogel scaffolds embedded with drug-loaded nanostructures—encompassing vesicles, micelles, emulsions or nanocapsules—have emerged as hybrid systems that significantly enhance bioavailability at the tumor site, demonstrating high efficacy against skin cancer. Additionally, solid nanoparticles benefit greatly from the hydrogel network, which serves not only as a scaffold to enhance photothermal therapy but also as a bioactive compound, promoting cancer cell death and wound healing. Finally, nanogels are highly adaptable and effective systems against metastization as they can be administered intravenously. We conclude by presenting perspectives on future directions in this field and challenges yet to be addressed. © 2024 The Author(s)

Abstract Micro/nanomotors represent a burgeoning field of research featuring small devices capable of autonomous movement in liquid environments through catalytic reactions and/or external stimuli. This review delves into recent advancements in light-driven semiconductor-based micro/nanomotors (LDSM), focusing on optimized syntheses, enhanced motion mechanisms, and emerging applications in the environmental and biomedical domains. The survey commences with a theoretical introduction to micromotors and their propulsion mechanisms, followed by an exploration of commonly studied LDSM, emphasizing their advantages. Critical properties affecting propulsion, such as surface features, morphology, and size, are presented alongside discussions on external conditions related to light sources and intensity, which are crucial for optimizing the propulsion speed. Each property is accompanied by a theoretical background and conclusions drawn up to 2018. The review further investigates recent adaptations of LDSM, uncovering underlying mechanisms and associated benefits. A brief discussion is included on potential synergistic effects between different external conditions, aiming to enhance efficiency-a relatively underexplored topic. In conclusion, the review outlines emerging applications in biomedicine and environmental monitoring/remediation resulting from recent LDSM research, highlighting the growing significance of this field. The comprehensive exploration of LDSM advancements provides valuable insights for researchers and practitioners seeking to leverage these innovative micro/nanomotors in diverse applications.

Abstract Purpose Pejao Mining Complex locates in Castelo de Paiva municipality and, until its closure in 1994, was one of the most important coal mines in the Douro Coalfield. This work aims to study the presence, quantify, and evaluate the dissemination of mercury (Hg), a potentially toxic element (PTE) of major public health concern by the World Health Organization (WHO), from a waste pile affected by coal fires.Materials and methods Samples from areas affected and unaffected by the combustion and from surrounding soil were collected from Fojo waste pile region. First, the Hg pseudo-total concentration was estimated for all collected samples by soil microwave-assisted digestion with aqua regia (USEPA 3051A). Then, a sequential extraction procedure (SEP), the USEPA 3200, was applied for Hg fractionation and speciation aiming to evaluate Hg mobility and bioavailability to surrounding ecosystems.Results and discussion The results obtained showed a Hg enrichment in soil samples when compared to Portuguese and international reference values for soils. Relatively to the Hg availability and mobility, although it predominates in the semi-mobile fraction, the waste pile materials exposed to combustion showed a concerning increase of Hg levels in the mobile fraction that contains the more labile Hg species, being a major source of environmental contamination by Hg.Conclusions This study allowed to conclude that combustion of mining residues increased Hg mobility, toxicity, and bioavailability, increasing the contamination potential of the coal waste pile. The methodology applied in this work can be replicated in other abandoned mines to monitor, control, and/or mitigate the Hg environmental impact in the surrounding soils and waters.

Abstract Reusing soils near abandoned mines requires the assessment of soil quality, which includes determining potentially toxic elements (PTEs), such as As, Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Sr, Zn and Zr. Levels of PTEs in soil can be harmful. Hence, the measurement of their concentrations is crucial to assess whether soil properties are reusable or it represents a potential environmental risk. Field techniques such as X-ray fluorescence (XRF) imprinting may be an option for rapid PTEs monitoring. Still, due to low sensitivity and selectivity, the partially obtained results by XRF software can be biased. This study presents an alternative solution for soil PTEs monitoring based on the advantages of multivariate analysis (MVA) principally partial least square (PLS) regression applied to orthogonally signal-corrected (OSC) XRF spectroscopic data. The developed PLS models were applied to soil samples from two regions of adjacent abandoned coal mines, in NW Portugal. High correlation coefficients obtained for As, Fe, Pb, Sr and Zn validation models (R2 = 0.79-0.99) pointed to the improved accuracy of their monitoring (compared to directly obtained XRF results) in this regional soil environment. The other PTEs (Co, Cr, Cu, Ni and Zr) showed good PLS models at local environment (R2 = 0.84-0.98). The test of these models in the contaminated regions reinforces their effectiveness in monitoring contaminated soils toward the reuse of environments near abandoned mines.