Publications

Abstract Recent advances in neuromorphic resistive switching have enabled us to start emulating biological synapses and neurons. A liquid switching medium brings these devices even closer to brain-like systems, being soft and flexible. Here, we propose copper solution-based artificial synapses that show both nonvolatile and volatile, and excitatory and inhibitory behavior, without an electroforming step. Different copper sulfate solutions, concentrations, electrode materials, and spacings were studied. Low operation voltage was achieved for the aqueous solution, showing high endurance and data retention. By changing solvation to glyceline, a change between nonvolatile and volatile dynamics occurred, while maintaining neuromorphic behavior and enhancing stability. This shows, for the first time, both potentiation and depression in a volatile device. Our results are promising for bio-voltage neuromorphic memristor-based interfaces.

Abstract The development of simple, selective, and cost-effective methods for quantification of bovine serum albumin (BSA) is currently very important for assessing milk quality (and safety). In this work, a new surface plasmon resonance (SPR) sensor was developed, consisting of imprinted hydrogel-based nanoparticles (nanoMIPs) immobilized on gold platforms, to quantify BSA in bovine milk. The nanoMIPs prepared for recognition of BSA were synthesized by the precipitation polymerization approach, using a synthetic BSA epitope (VVSTQTALA) as template. The spherical MIP nanoparticles (NPs) had an average size of 60 nm. The binding studies performed revealed that the binding affinity of the prepared nanoMIPs to BSA (KD = 7.1 × 10−6 mol L−1) was comparable to that obtained by a natural BSA antibody (KD = 2.5 × 10−6 mol L−1). The plasmonic sensor incorporating the MIP nanomaterials achieved a limit of detection (LOD) of 1.02 × 10−6 mol L−1 (0.068 mg mL−1) and a limit of quantification (LOQ) of 3.39 × 10−6 mol L−1 (0.225 mg mL−1), over a linear range from 2.0 × 10−6 mol L−1 to 1.5 × 10−5 mol L−1. Moreover, the selectivity studies revealed a significant sensor response towards casein and a negligible response towards vancomycin. In the end, the optical sensor was tested against commercial milk samples, showing promising viability for detection of BSA as the value reported by the plasmonic sensor ((1.0 ± 0.1) × 10−4 mol L−1) was very close to that obtained by size exclusion-high-performance liquid chromatography (SEC-HPLC). © 2025 The Author(s)

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 Efficient and rapid detection of bacterial pathogens is crucial for food safety and effective disease control. While conventional methods such as PCR and ELISA are accurate, they are time-consuming, costly, and often require specialized infrastructure. Recently, electrochemical biosensors integrating graphene nanomaterials with bacteriophages-termed graphages-have emerged as promising platforms for pathogen detection, offering fast, specific, and highly responsive detection. This review critically examines all electrochemical biosensors reported to date that utilize graphene-phage hybrids. Key aspects addressed include the types of graphene nanomaterials and bacteriophages used, immobilization strategies, electrochemical transduction mechanisms, and sensor metrics-such as detection limits, linear ranges, and ability to perform in real matrices. Particular attention is given to the role of phage orientation, surface functionalization, and the use of receptor binding proteins. Finally, current limitations and opportunities for future research are outlined, including prospects for genetic engineering and sensor miniaturization. This review serves as a comprehensive reference for researchers developing phage-based biosensors, especially those interested in integrating carbon nanomaterials for improved electroanalytical performance.

Abstract The incorporation of lambda-cyhalothrin (LC) in lipid nanoparticles (LN) could be a sustainable strategy to increase its efficacy and decrease its hazard to the environment. The purpose of the present work was to perform the interaction between LC and LN after nanoencapsulation and to evaluate their effect on species from different aquatic trophic levels such as Aliivibrio fischeri, Raphidocelis subcapitata, Lemna minor, and Daphnia magna. LN loaded with LC (LN-LC) were produced by green and simple methodology without organic solvents using Precirol ATO5 (R) and Capryol 90 (R) as solid and liquid lipids, respectively, and soy lecithin and TEGO (R) Care as emulsifiers. The physicochemical interaction between LC and LN was assessed by differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR), and X-ray, confirming that LC is associated with the lipid lattice of nano- particles, characterized by an amorphous matrix. The data from biological tests showed no or low toxicity of LNLC on the selected aquatic organisms. Thus, encapsulation in lipid-based nanoparticles may be a promising and sustainable choice for using this insecticide in agricultural practices, reducing its environmental risk.

Abstract This study presents a comprehensive investigation of the morphological and photocatalytic properties of electrochemically synthesized titanium dioxide (TiO2), both in its amorphous (non-calcined) and crystalline (calcinated) forms and its composite with biomass-derived carbon (TiO2@C). The TiO2 materials were synthesized using a deep eutectic solvent (DES)-based electrochemical method, and their properties were compared with commercial TiO2 nano-powder (TiO2_NP). Characterization techniques such as BET, SEM/EDX, XRD, Raman, ATR-FTIR, and XPS were employed to elucidate the structural, textural, and surface chemical properties of the materials. The amorphous TiO2 (TiO2@DES) exhibited significantly higher surface area and pore volume compared to commercial TiO2, while the calcined TiO2 (TiO2@DES_400) displayed enhanced crystallinity with an anatase structure. The TiO2@C composite was prepared via an in-situ decoration of biomass-derived carbon during the TiO2 electrochemical synthesis. This resulted in a material with a high specific surface area (2214 m(2) g(-1)) and porous structure. This composite demonstrated superior photocatalytic performance for the degradation of crystal violet dye under both UV and visible light irradiation, achieving degradation efficiencies of similar to 98 % after 5 h. The TiO2@C composite was further applied to degrade wastewater from leather dye processing, demonstrating its efficacy in real-world applications. These results underscore the potential of the TiO2@C composite as a sustainable and high-performance photocatalyst for environmental remediation, particularly in wastewater treatment.

Abstract With the rapidly increasing demand for sustainable battery systems comes the need for environmentally friendly, cost-effective, and scalable material production. The reutilisation of biomass waste as precursors for carbonaceous materials shows promise in tackling some of these issues, especially when considered as sulfur hosts for lithium-sulfur (Li-S) batteries. In this work, amorphous, porous carbon particles are produced through the facile carbonisation of glycogen derived from the industrial wastewater stream of the mussel cooking process. The influence of carbonisation time on the structural and molecular properties of the carbon particles is investigated using gas absorption analysis, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, scanning transmission electron microscopy, and attenuated total reflectance Fourier transform infrared spectroscopy. The application of these shellfish waste glycogen-derived carbons as sulfur host materials for Li-S batteries is detailed for the first time, including galvanostatic cycling and cyclic voltammetry. Specific charge values obtained in this study are greater than many reported values for carbons prepared from other biomass sources including rice husks and peanut shells. This work highlights the possibility to derive low-cost, sustainable sulfur host materials with promising electrochemical performance from shellfish materials which are currently considered to be waste products.

Abstract This study presents an environmentally friendly approach for synthesis Ag-TiO2 composite using pulsed reverse current (PRC) electrodeposition from green electrolytes, specifically deep eutectic solvents (DESs). The combination of PRC and DESs offers better control over nanoparticle synthesis while eliminating the need for toxic or expensive precursors, representing a significant advancement in sustainable nanomaterial synthesis. Different electrochemical parameters were adjusted, and their influence on the structure and morphology of the composite was investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM analysis revealed that silver nanoparticles (Ag NPs) are attached to TiO2 nanopowder, with the coexistence of TiO2 and Ag further confirmed by XRD and XPS. The recorded UV-Vis diffuse reflectance spectra (DRS) displayed a broad peak in the range of 400 - 650 nm, associated with the localized surface plasmon resonance (LSPR) of Ag NPs on the semiconductor's surface. The photocatalytic activity of TiO2 nanopowder and Ag-TiO2 composite was evaluated based on the degradation of methyl orange (MO) dye under UV and visible light illumination. Our findings clearly demonstrated that the incorporation of Ag improved the photocatalytic efficiency. The mechanism of MO dye degradation was explored by using various scavengers, revealing that superoxide radicals (center dot O-2(-)) play a dominant role. Furthermore, the incorporation of Ag NPs significantly enhanced the antimicrobial activity of the oxide against both Gram-positive (B. subtilis) and Gram-negative (E.coli) strains.

Abstract Soil acts as a natural 'filter', playing a crucial role in the transfer of geogenic and anthropogenic pollutants from abandoned coal mine sites to surrounding water bodies. Key indicators of soil contamination, such as pH, electrical conductivity (EC), and organic matter (OM), expressed as loss-on-ignition (LOI), can signal contamination risks when they deviate from optimal ranges. To enable sustainable risk assessment through monitoring of pH, EC, and LOI, streamlined spectroscopic techniques Fourier transform infrared (FTIR), near-infrared (NIR), Raman, and X-ray fluorescence (XRF) were applied in combination with multivariate analysis (MVA), to soil samples from two abandoned coal mines in NW Portugal. Partial least squares (PLS) regression models demonstrated that XRF spectroscopic data provided the most accurate assessment of soil pH, EC, and LOI at the local scale (R2 = 0.92-0.99). The most significant spectroscopic signatures, identified through weighted regression coefficients (Bw), enabled robust predictions of these key soil parameters. These findings highlight that these geochemical variables outperform molecular spectroscopy techniques for efficient and environmentally relevant risk monitoring of contamination in abandoned coal mine sites.

Abstract Due to the high quantities of solid waste with high concentrations of chromium that the footwear industry produces and its disposal sites, it is vital to understand whether leather residue itself is harmful to the ecosystem. Thus, a microcosm test with multispecies (Brassica oleracea and Eisenia fetida) was carried out using an agricultural soil contaminated with two different leather residues (Wet Blue and Finished Leather) from the footwear industry. After the stabilization period, Brassica oleracea seedlings and Eisenia fetida adults were exposed to these treatments. At the end of the experiment, a series of parameters were analysed in the B. oleracea leaves (leaf chlorophyl content, gas exchange measurements and photosynthetic parameters), in the E. fetida organisms (alkaline comet assay and biomarkers such as acetylcholinesterase and lipid peroxidation) and in the soils (total chromium content, enzymes activity and nitrogen mineralization and potential nitrification). In the case of soil’s enzymatic activity, even though some were significantly altered, no negative effects could be attributed to the leather residues. Moreover, the addition of residues to the soil did not significantly affect the plant species; however, the same was not observed for the earthworm E. fetida when in contact with Finished Leather. Overall, Finished Leather residue was the one that caused more effects on the parameters analysed and therefore its disposal should be carefully examined.