Open Access
Nanoflowers versus magnetosomes: comparison between two promising candidates for magnetic hyperthermia therapy
(IEEE, 2021) Jefremovas, Elizabeth M.; Gandarias, Lucía; Rodrigo, Irati; Marcano, Lourdes; Gruttner, Cordula; García, José Ángel; Garayo Urabayen, Eneko; Orue, Iñaki; García-Prieto, Ana; Muela, Alicia; Fernández-Gubieda, María Luisa; Alonso Masa, Javier; Fernández Barquín, Luis; Ciencias; Zientziak
Magnetic Fluid Hyperthermia mediated by iron oxide nanoparticles is one of the mostpromising therapies for cancer treatment. Among the different candidates, magnetite and maghemite nanoparticles have revealed to be some of the most promising candidates due to both their performance andtheir biocompatibility. Nonetheless, up to date, the literature comparing the heating efficiency of magnetiteand maghemite nanoparticles of similar size is scarce. To fill this gap, here we provide a comparison between commercial Synomag Nanoflowers (pure maghemite) and bacterial magnetosomes (pure magnetite)synthesized by the magnetotactic bacterium Magnetospirillum gryphiswaldenseof〈D〉 ≈40–45 nm. Bothtypes of nanoparticles exhibit a high degree of crystallinity and an excellent degree of chemical purity andstability. The structural and magnetic properties in both nanoparticle ensembles have been studied by meansof X–Ray Diffraction, Transmission Electron Microscopy, X–Ray Absorption Spectroscopy, and SQUIDmagnetometry. The heating efficiency has been analyzed in both systems using AC magnetometry at severalfield amplitudes (0–88 mT) and frequencies (130, 300, and 530 kHz).
Open Access
Steering the synthesis of Fe3O4 nanoparticles under sonication by using a fractional factorial design
(Elsevier, 2021) Echeverría Morrás, Jesús; Moriones Jiménez, Paula; Garrido Segovia, Julián José; Ugarte Martínez, María Dolores; Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Superparamagnetic iron oxide nanoparticles (MNPs) have the potential to act as heat sources in magnetic hyperthermia. The key parameter for this application is the specific absorption rate (SAR), which must be as large as possible in order to optimize the hyperthermia treatment. We applied a Plackett-Burman fractional factorial design to investigate the effect of total iron concentration, ammonia concentration, reaction temperature, sonication time and percentage of ethanol in the aqueous media on the properties of iron oxide MNPs. Characterization techniques included total iron content, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, High Resolution Transmission Electron Microscopy, and Dynamic Magnetization. The reaction pathway in the coprecipitation reaction depended on the initial Fe concentration. Samples synthesized from 0.220 mol L−1 Fe yielded magnetite and metastable precipitates of iron oxyhydroxides. An initial solution made up of 0.110 mol L−1 total Fe and either 0.90 or 1.20 mol L−1 NH3(aq) led to the formation of magnetite nanoparticles. Sonication of the reaction media promoted a phase transformation of metastable oxyhydroxides to crystalline magnetite, the development of crystallinity, and the increase of specific absorption rate under dynamic magnetization.
Open Access
Nanoscale engineering of cobalt-gallium co-doped ferrites: a strategy to enhance high-frequency theranostic magnetic materials
(American Chemical Society, 2025-07-01) Galarreta Rodríguez, Itziar; Liguori, Deborah; Garayo Urabayen, Eneko; Muzzi, Beatrice; Cervera Gabalda, Laura María; Rubio Zuazo, Juan; Gomide, Guilherme; Depeyrot, Jérõm; López Ortega, Alberto; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Publica de Navarra / Nafarroako Unibertsitate Publikoa
The nanoscale engineering of doped iron oxide magnetic nanoparticles has attracted significant interest in recent years for high-frequency theragnostic applications, where simultaneous diagnosis and therapy are required. In particular, their ability to generate localized heating under alternating magnetic fields makes them ideal candidates for magnetic hyperthermia, a noninvasive cancer treatment technique. However, understanding the complex interplay between multiple dopant cations and their impact on dynamic magnetic behavior remains a significant challenge. In this work, we present a comprehensive study on how two differently marked cations (Co2+ and Ga3+) can modify both the magnetic properties of these nanoparticles and their efficiency in heat generation under alternating magnetic fields. To this end, a series of nanoparticles with the formula CoxGa0.15Fe2.85-xO4 (0 < x < 0.3) was prepared via thermal decomposition, enabling the production of monodisperse nanocrystals with high crystallinity and precise stoichiometric control. Their exhaustive structural and magnetic characterization confirmed site-selective incorporation of Ga3+ into tetrahedral sites and Co2+ into octahedral sites. Increasing the cobalt content within the gallium-doped framework leads to enhanced magnetocrystalline anisotropy and higher saturation magnetization, both crucial parameters for efficient heat dissipation in magnetic hyperthermia. The study further demonstrates that the dynamic magnetic response of these nanostructures is strongly influenced by the interplay between doping composition, anisotropy, and the amplitude of the applied magnetic field. These findings highlight the effectiveness of nanoscale codoping strategies in fine-tuning magnetic behavior and optimizing the performance of spinel ferrite nanoparticles for advanced biomedical and technological applications, particularly high-frequency magnetic hyperthermia.
Open Access
Electromagnetic vibrational harvester based on U-shaped ferromagnetic cantilever: a novel two-magnet configuration
(Elsevier, 2024-10-01) Gandía Aguado, David; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Royo Silvestre, Isaac; Cruz Blas, Carlos Aristóteles de la; Tainta Ausejo, Santiago; Gómez Polo, Cristina; Ciencias; Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC
Electromagnetic vibrational harvesters are low-cost devices featuring high-power densities and robust structures, often used for capturing the energy of environmental vibrations (civil infrastructures, transportation, human motion, etc.,). Based on Faraday’s law, energy generation relies on the modification of the magnetic field distribution within a magnetic element caused by mechanical vibrations inducing an electromotive force (EMF) in a pick-up coil. However, the practical implementation of this type of vibrational harvester is currently limited due to the reduced generated power under low-frequency vibrations. In this work, an electromagnetic vibrational harvester is experimentally characterized and analyzed employing magnetic circuit analysis. The harvester consists of a ferromagnetic U-shaped cantilever, a NdFeB magnet and a ferrite magnet used as “magnetic tip mass” to enhance the magnetic flux changes under vibrations of frequency < 100 Hz. For this configuration, an experimental voltage of ∼ 1.2 V peak-to-peak (open circuit) was obtained at a resonant frequency of 77 Hz, enabling the subsequent electronic rectification stage. Additionally, Finite Element Method (FEM) is used to explore different design possibilities including the modeling of complex geometries, mechanical properties and non-linear magnetic materials, enabling the tuning of the resonance frequency from 51 to 77 Hz, keeping constant the induced voltage.
Open Access
Preparation of selenium-based drug-modified polymeric ligand-functionalised Fe3O4 nanoparticles as multimodal drug carrier and magnetic hyperthermia inductor
(MDPI, 2023) Galarreta Rodríguez, Itziar; Etxebeste-Mitxeltorena, Mikel; Moreno, Esther; Plano, Daniel; Sanmartín, Carmen; Megahed, Saad; Feliu, Neus; Parak, Wolfgang J.; Garayo Urabayen, Eneko; Gil de Muro, Izaskun; Lezama, Luis; Ruiz de Larramendi, Idoia; Insausti, Maite; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
In recent years, much effort has been invested into developing multifunctional drug delivery systems to overcome the drawbacks of conventional carriers. Magnetic nanoparticles are not generally used as carriers but can be functionalised with several different biomolecules and their size can be tailored to present a hyperthermia response, allowing for the design of multifunctional systems which can be active in therapies. In this work, we have designed a drug carrier nanosystem based on Fe3O4 nanoparticles with large heating power and 4-amino-2-pentylselenoquinazoline as an attached drug that exhibits oxidative properties and high selectivity against a variety of cancer malignant cells. For this propose, two samples composed of homogeneous Fe3O4 nanoparticles (NPs) with different sizes, shapes, and magnetic properties have been synthesised and characterised. The surface modification of the prepared Fe3O4 nanoparticles has been developed using copolymers composed of poly(ethylene-alt-maleic anhydride), dodecylamine, polyethylene glycol and the drug 4-amino-2-pentylselenoquinazoline. The obtained nanosystems were properly characterised. Their in vitro efficacy in colon cancer cells and as magnetic hyperthermia inductors was analysed, thereby leaving the door open for their potential application as multimodal agents.
Open Access
Monitoring structural transformations in metamagnetic shape memory alloys by non-contact GMI technology
(IOP Publishing, 2023) Beato López, Juan Jesús; La Roca, Paulo Matías; Algueta-Miguel, Jose M.; Garayo Urabayen, Eneko; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC; Zientziak; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Different applications based on metamagnetic shape memory alloy (MSMA) require monitoring the evolution of the martensitic transformation (MT) to optimize the actuation mechanism. To avoid interaction with the active material, a non-contact technique would be ideal. Nevertheless, non-contact detection involves complex methods like diffraction, optical analysis, or electromagnetic technology. The present work demonstrates that the MT can be monitored without interaction with the active material using a low-cost technology based on the Giant Magnetoimpedance (GMI) effect. The GMI sensor is based on a (CoFe)SiB soft magnetic wire submitted to an alternating current and whose second harmonic voltage variation allows to detect changes in the strength of the stray magnetic fields linked to the metamagnetic phase transition. The sensor has been tested using the MT of a NiMnInCo MSMA. A specific application for environmental temperature control using the non-contact GMI sensor is proposed.
Open Access
Magnetic-field-assisted photocatalysis of N-TiO2 nanoparticles
(IEEE, 2023-09-04) Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Pérez de Landazábal Berganzo, José Ignacio; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Nitrogen doped TiO2 nanoparticles were synthesized through solvothermal method employing Ti (IV) butoxide and HNO3 as precursors. Structural and optical characterizations confirm their nanometer nature (sizes around 10 nm) and the band-gap energy values in the UV range (3.2 eV). Nitrogen doping enhances the occurrence of optical Urbach tails extending towards the visible region. Visible photocatalytic performance (degradation of methyl orange) is correlated with maximum values in the magnetic susceptibility linked to a magnetic polarization of the anatase structure via defects (oxygen vacancies). The application of magnetic field provides a positive effect (acceleration in reaction kinetics) within the UV-Vis range.
Open Access
Modulating photocatalytic activity of nitrogen doped TiO2 nanoparticles via magnetic field
(Elsevier, 2024-07-30) Gómez Polo, Cristina; Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The effect of the magnetic field on the photocatalytic activity of TiO2-based nanoparticles is analyzed using a magnetically-assisted photoreactor with permanent magnets to generate a controlled uniform magnetic field, B (¿82 mT). Nitrogen doped TiO2 nanoparticles (sizes around 10 nm) were synthesized through a solvothermal method employing Ti(IV) butoxide and HNO3 (x = 0, 0.5, 1, 1.5 and 2 mL) as precursors and their structural, optical and magnetic properties were analyzed. Specifically, nitrogen doping is confirmed through Hard X-ray Photoelectron Spectroscopy (HAXPES) in those samples synthesized with low HNO3 concentrations (x = 0.5, 1). The correlation between spin polarization (magnetic susceptibility) and visible photocatalytic activity (methyl orange as a model organic pollutant) is particularly analyzed. Surprisingly, opposite effects of the magnetic field on the photocatalytic performance are found in the visible range (above 400 nm) or under UV-Vis irradiation (decrease and increase in the photocatalytic activity, respectively, under magnetic field). The Langmuir-Hinshelwood model allows us to conclude that the strong decrease in adsorption under the magnetic field (around 42 % for x = 0.5) masks the increase in the kinetic constant (close to 58 % for x = 0.5) related mainly to the effect of Lorentz forces on the reduction of the electron-hole recombination.
Open Access
Fe-C nanoparticles obtained from thermal decomposition employing sugars as reducing agents
(Elsevier, 2020) Cervera Gabalda, Laura María; Pérez de Landazábal Berganzo, José Ignacio; Garayo Urabayen, Eneko; Monteserín, María; Larumbe Abuin, Silvia; Martín, F.; Gómez Polo, Cristina; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The aim of the work is to present a comparative analysis (structural and magnetic) of Fe-C nanocomposites obtained by the thermal decomposition of sugars (fructose, glucose and sucrose) employing FeCl3 as Fe3+ precursor. The thermal decomposition was followed through Thermogravimetry (TGA) and Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. The results indicate the reduction of Fe3+ under the performed thermal treatments and the achievement at high annealing temperatures of Fe-C nanostructures (coexistence of α-Fe and Fe3C nanoparticles surrounded by a carbon matrix). The magnetic characterization performed by dc SQUID magnetometry, shows an antiferromagnetic response in the initial stages of the decomposition process, and a ferromagnetic behavior linked to the Fe-based nanoparticles. The magnetic induction heating was analyzed through the ac hysteresis loops. Moderate Specific Absorption Rate (SAR) is obtained in Fe-C nanoparticles (~ 70 W/gFe), ascribed to the large nanoparticle size. The combination of porous carbon structure and ferromagnetic response of the Fe-C nanoparticles (i.e. local temperature increase under ac magnetic field) enlarge the emerging applications of these carbonaceous nanocomposites.
Open Access
Unlocking the potential of magnetotactic bacteria as magnetic hyperthermia agents
(Wiley, 2019) Gandía Aguado, David; Gandarias, Lucía; Rodrigo, Irati; Robles García, Joshua; Das, Raja; Garayo Urabayen, Eneko; García, José Ángel; Ciencias; Zientziak
Magnetotactic bacteria are aquatic microorganisms that internally biomineralize chains of magnetic nanoparticles (called magnetosomes) and use them as a compass. Here it is shown that magnetotactic bacteria of the strain Magnetospirillum gryphiswaldense present high potential as magnetic hyperthermia agents for cancer treatment. Their heating efficiency or specific absorption rate is determined using both calorimetric and AC magnetometry methods at different magnetic field amplitudes and frequencies. In addition, the effect of the alignment of the bacteria in the direction of the field during the hyperthermia experiments is also investigated. The experimental results demonstrate that the biological structure of the magnetosome chain of magnetotactic bacteria is perfect to enhance the hyperthermia efficiency. Furthermore, fluorescence and electron microscopy images show that these bacteria can be internalized by human lung carcinoma cells A549, and cytotoxicity studies reveal that they do not affect the viability or growth of the cancer cells. A preliminary in vitro hyperthermia study, working on clinical conditions, reveals that cancer cell proliferation is strongly affected by the hyperthermia treatment, making these bacteria promising candidates for biomedical applications.