Open Access
Tuning the photocatalytic performance through magnetization in Co-Zn ferrite nanoparticles
(Elsevier, 2022) Cervera Gabalda, Laura María; Zielinska-Jurek, Anna; Gómez Polo, Cristina; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
In this work, the link between the photocatalytic performance of Co-Zn ferrite nanoparticles and the net magnetic moment is analyzed. CoxZn1-xFe2O4 nanoparticles (0 ≤ x ≤ 1) were synthesized by co-precipitation method and different physicochemical techniques were employed to characterize the samples (X-ray diffraction, Transmission Electron Microscopy (TEM), BET surface area, Diffuse Reflectance Spectroscopy (DRS), Photoluminescence spectroscopy, Z-potential, SQUID magnetometry). Enhanced photocatalytic degradation (maximum degradation ratios of two emerging pollutants, phenol and toluene) are found in those nanoparticles (0.4 ≤ x ≤ 0.6) with optimum magnetic response (i.e. superparamagnetism at room temperature and high saturation magnetization). The magnetization of the nanoparticles turns out to be the determining factor in the optimization of the photocatalytic response, since there is no clear relationship with other physicochemical parameters (i.e. specific surface area, isoelectric point, band gap energy or photoluminescence). These results support the current field of research related to photocatalytic performance enhancement through magnetic field effects.
Open Access
Fe3O4-SiO2 mesoporous core/shell nanoparticles for magnetic field-induced ibuprofen-controlled release
(American Chemical Society, 2022-12-23) García Rodríguez, Lucía; Garayo Urabayen, Eneko; López Ortega, Alberto; Galarreta Rodríguez, Itziar; Cervera Gabalda, Laura María; Cruz Quesada, Guillermo; Cornejo Ibergallartu, Alfonso; Garrido Segovia, Julián José; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA2020; Gobierno de Navarra / Nafarroako Gobernua
Hybrid magnetic nanoparticles made up of an iron oxide, Fe3O4, core and a mesoporous SiO2 shell with high magnetization and a large surface area were proposed as an efficient drug delivery platform. The core/shell structure was synthesized by two seed-mediated growth steps combining solvothermal and sol—gel approaches and using organic molecules as a porous scaffolding template. The system presents a mean particle diameter of 30(5) nm (9 nm magnetic core diameter and 10 nm silica shell thickness) with superparamagnetic behavior, saturation magnetization of 32 emu/g, and a significant AC magnetic-field-induced heating response (SAR = 63 W/gFe3O4, measured at an amplitude of 400 Oe and a frequency of 307 kHz). Using ibuprofen as a model drug, the specific surface area (231 m2/g) of the porous structure exhibits a high molecule loading capacity (10 wt %), and controlled drug release efficiency (67%) can be achieved using the external AC magnetic field for short time periods (5 min), showing faster and higher drug desorption compared to that of similar stimulus-responsive iron oxide-based nanocarriers. In addition, it is demonstrated that the magnetic field-induced drug release shows higher efficiency compared to that of the sustained release at fixed temperatures (47 and 53% for 37 and 42 °C, respectively), considering that the maximum temperature reached during the exposure to the magnetic field is well below (31 °C). Therefore, it can be hypothesized that short periods of exposure to the oscillating field induce much greater heating within the nanoparticles than in the external solution.
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
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
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.