Artículos de revista DCIE - ZIES Aldizkari artikuluak

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Browsing Artículos de revista DCIE - ZIES Aldizkari artikuluak by Author "Abad Díaz de Cerio, Ana"

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    PublicationOpen Access
    Antibacterial performance of Co-Zn ferrite nanoparticles under visible light irradiation
    (Wiley, 2024-11-20) Gubieda, Alicia G.; Abad Díaz de Cerio, Ana; García-Prieto, Ana; Fernández-Gubieda, María Luisa; Cervera Gabalda, Laura María; Ordoqui Huesa, Eduardo; Cornejo Ibergallartu, Alfonso; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
    BACKGROUND: To address water scarcity and promote sustainable resource management, more efficient and cost-effective water treatment solutions are necessary. Particularly, pathogens in drinking water are a topic of growing concern. One promising technology is the use of photocatalytic nanoparticles activated by visible light as antibacterial agents. This study focuses on the characterization and antibacterial properties of Co-Zn ferrite nanocatalysts, tested against Escherichia coli. RESULTS: The CoxZn1¿xFe2O4 (x = 0, 0.1, 0.4 and 0.6) ferrites were synthesized by the co-precipitation method. Structural, morphological and optical analyses confirmed that these nanoparticles have a cubic spinel structure, with sizes of around 10 nm, and band gap energies suitable for visible light activation (1.4¿1.7 eV). The antibacterial efficacy of the nanoparticles against E. coli was tested and compared with their photocatalytic performance employing phenol as organic pollutant model (highest phenol degradation for x = 0.6). Specifically, the antibacterial capacity of these nanoparticles was evaluated by comparing the ability of bacteria to grow after being incubated with the nanoparticles under visible light and in the dark. It was found that nanoparticles with lower cobalt content (x = 0 and 0.1) significantly reduced bacterial culturability under visible light. Transmission Electron Microscopy analysis revealed that nanoparticles with cobalt content caused bacteria to secrete biofilm, potentially offering some protection against the nanoparticles. CONCLUSION: ZnFe2O4 nanoparticles show the highest antibacterial effect amongst those tested. This is attributed to the combined action of Zn2+ ion release and the photocatalytic effect under visible light. Furthermore, Zn might inhibit protective biofilm secretion, leading to higher antibacterial effects.
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    PublicationOpen Access
    Exploring the complex interplay of anisotropies in magnetosomes of magnetotactic bacteria
    (American Chemical Society, 2025-04-14) Gandía Aguado, David; Marcano, Lourdes; Gandarias, Lucía; Gubieda, Alicia G.; García-Prieto, Ana; Fernández Barquín, Luis; Espeso, José Ignacio; Martín Jefremovas, E.; Orue, Iñaki; Abad Díaz de Cerio, Ana; Fernández-Gubieda, María Luisa; Alonso Masa, Javier; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
    Magnetotactic bacteria (MTB) are at the forefront of interest for biophysics applications, especially in cancer treatment. Magnetosomes biomineralized by these bacteria are high-quality magnetic nanoparticles that form chains inside the MTB through a highly reproducible, naturally driven process. In particular, Magnetovibrio blakemorei and Magnetospirillum gryphiswaldense MTB exhibit distinct magnetosome morphologies: truncated hexa-octahedral and cuboctahedral shapes, respectively. Despite having identical compositions (magnetite, Fe3O4) and dimensions within a similar size range, their effective uniaxial anisotropies significantly differ at room temperature, with M. blakemorei exhibiting ∼25 kJ/m3 and M. gryphiswaldense ∼ 11 kJ/m3. This prominent anisotropy variance provides a unique opportunity to explore the role of magnetic anisotropy contributions in the magnetic responses of these magnetite-based nanoparticles. This study systematically investigates these responses by examining static magnetization as a function of temperature (M vs T, 5 mT) and magnetic field (M vs μ0H, up to 1 T). Above the Verwey transition temperature (∼110 K), the effective anisotropy is dominated by the shape anisotropy contribution, notably increasing the coercivity for M. blakemorei by up to twofold compared to M. gryphiswaldense. However, below this temperature, the effective uniaxial anisotropy rapidly increases in a nonmonotonic way, significantly changing the magnetic behavior. Computational simulations using a dynamic Stoner–Wohlfarth model provide insights into these phenomena, enabling careful interpretation of experimental data. According to our simulations, below the Verwey temperature, a uniaxial magnetocrystalline contribution progressively emerges, peaking around 22–24 kJ/m3 at 5 K. Our study reveals the complex evolution of magnetocrystalline contributions, which dominate the magnetic response of magnetosomes below the Verwey temperature. This demonstrates the profound impact of anisotropic properties on the magnetic behaviors and applications of magnetite-based nanoparticles and highlights the exceptional utility of magnetosomes as ideal model systems for studying the complex interplay of anisotropies in magnetite-based nanoparticles.