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
Magnetically recyclable TiO2/MXene/MnFe2O4 photocatalyst for enhanced peroxymonosulphate-assisted photocatalytic degradation of carbamazepine and ibuprofen under simulated solar light
(Elsevier, 2023) Grzegórska, Anna; Ofoegbu, Joseph Chibueze; Cervera Gabalda, Laura María; Gómez Polo, Cristina; Sannino, Diana; Zielinska-Jurek, Anna; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
In this study, a novel TiO2/Ti3C2/MnFe2O4 magnetic photocatalyst with dual properties, enabling (i) improved photocatalytic degradation with PMS activation under simulated solar light and (ii) magnetic separation after the degradation process in an external magnetic field was developed and applied for the efficient photodegradation pharmaceutically active compounds (PhACs) frequently present in wastewater and surface waters worldwide. MXene was used as a Ti precursor for anatase/rutile synthesis and as a co-catalyst in the photodegradation process. Manganese ferrite with ferrimagnetic properties was coupled with the TiO2/Ti3C2 composite to facilitate the magnetic separation after the purification process in an external magnetic field. Moreover, MnFe2O4 was used for PMS activation, producing •SO4- radicals with a strong oxidation ability and higher redox potential of 2.5–3.1 V (vs. NHE) than •OH radicals with a standard oxidation–reduction potential of 2.8 V. The effect of the manganese ferrite content in the composite structure (5 wt% and 20 wt%) on the physicochemical properties and photocatalytic activity of the magnetic photocatalyst was investigated. Furthermore, the most photocatalytic active composite of TiO2/MXene/5%MnFe2O4 was used for peroxymonosulphate-assisted photocatalytic degradation of ibuprofen and carbamazepine. The effect of peroxymonosulphate concentration (0.0625 mM, 0.125 mM, and 0.25 mM) and the synergistic effect of PMS activation on photocatalytic degradation was studied. Based on the obtained results, it was found that TiO2/MXene/5%MnFe2O4/PMS process is an efficient advanced treatment technology for the oxidation of emerging contaminants that are not susceptible to biodegradation. Carbamazepine and ibuprofen were completely degraded within 20 min and 10 min of the PMS-assisted photodegradation process under simulated solar light. The trapping experiments confirmed that •SO4- and •O2- are the main oxidising species involved in the CBZ degradation, while •SO4- and h+ in the IBP degradation. Furthermore, introducing interfering ions of Na+, Ca2+, Mg2+, Cl-, and SO42– in the model seawater did not affect the removal efficiency of both pharmaceuticals. In terms of reusability, the performance of the TiO2/MXene/5%MnFe2O4/PMS photocatalyst was stable after four subsequent cycles of carbamazepine and ibuprofen degradation.
Open Access
Insight into (electro)magnetic interactions within facet-engineered BaFe 12 O 19 /TiO 2 magnetic photocatalysts
(American Chemical Society, 2023) Dudziak, Szymon; Gómez Polo, Cristina; Karczewski, Jakub; Nikiforow, Kostiantyn; Zielinska-Jurek, Anna; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
A series of facet-engineered TiO2/BaFe12O19 composites were synthesized through hydrothermal growth of both phases and subsequent deposition of the different, faceted TiO2 nanoparticles onto BaFe12O19 microplates. The well-defined geometry of the composite and uniaxial magnetic anisotropy of the ferrite allowed alternate interfaces between both phases and fixed the orientation between the TiO2 crystal structure and the remanent magnetic field within BaFe12O19. The morphology and crystal structure of the composites were confirmed by a combination of scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses together with the detailed study of BaFe12O19 electronic and magnetic properties. The photocatalytic activity and magnetic field effect were studied in the reaction of phenol degradation for TiO2/BaFe12O19 and composites of BaFe12O19 covered with a SiO2 protective layer and TiO2. The observed differences in phenol degradation are associated with electron transfer and the contribution of the magnetic field. All obtained magnetic composite materials can be easily separated in an external magnetic field, with efficiencies exceeding 95%, and recycled without significant loss of photocatalytic activity. The highest activity was observed for the composite of BaFe12O19 with TiO2 exposing {1 0 1} facets. However, to prevent electron transfer within the composite structure, this photocatalyst material was additionally coated with a protective SiO2 layer. Furthermore, TiO2 exposing {1 0 0} facets exhibited significant synergy with the BaFe12O19 magnetic field, leading to 2 times higher photocatalytic activity when ferrite was magnetized before the process. The photoluminescence emission study suggests that for this particular combination, the built-in magnetic field of the ferrite suppressed the recombination of the photogenerated charge carriers. Ultimately, possible effects of complex electro/magnetic interactions within the magnetic photocatalyst are shown and discussed for the first time, including the anisotropic properties of both phases.
Open Access
Effect of Cu substitution on the magnetic and magnetic induction heating response of CdFe₂O₄ spinel ferrite
(Elsevier, 2020) Ghasemi, R.; Echeverría Morrás, Jesús; Pérez de Landazábal Berganzo, José Ignacio; Beato López, Juan Jesús; Naseri, M.; Gómez Polo, Cristina; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
In this work, a comparative study of the effect of Cu on the structural, magnetic and magnetic induction heating response in CdFe2O4 spinel is presented. The ceramic nanoparticles (Cu1−xCdxFe2O4; 0 ≤ x ≤ 1) were synthesized by co-precipitation from Cu(II), Cd(II) and Fe(III) salts. The samples, characterized by X-ray diffractometry, display the characteristic spinel cubic structure (space group Fm3m) where CdO is detected as main secondary phase (≈ 16% weight for x = 1). A high degree of nanoparticle agglomeration is inferred from the Transmission Electron Microscopy (TEM) images, as a consequence of the employed synthesis procedure. Regarding the magnetic properties, superparamagnetic behavior at room temperature can be disregarded according to the low field magnetization response (ZFC-FC curves). For 0.4 ≤ x ≤ 0.8 ratios, the samples display maximum values in the magnetic moment that should be correlated to the cation distribution between the octahedral and tetrahedral sites. Maximum magnetization values lead to an enhancement in the magnetic induction heating response characterized by highest heating temperatures under the action of an ac magnetic field. In particular, maximum SAR values are estimated for x = 0.8 as a combined effect of high magnetic moment, low dc coercive field (high susceptibility). Although these Cu-Cd ferrite nanoparticles display moderate SAR values (around 0.7 W/g), the control of the maximum heating temperatures through the cation distribution (composition) provides promising properties to be used as nanosized heating elements (i.e. hyperthermia agents).
Open Access
Heatable magnetic nanocomposites with Fe3O4 nanocubes
(Elsevier, 2022-09-27) Larumbe Abuin, Silvia; Lecumberri, Cristina; Monteserín, María; Fernández, Lorea; Medrano Fernández, Ángel María; Garayo Urabayen, Eneko; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The development of magnetic self-heating polymers is an area of great interest for many applications. The intrinsic magnetic properties of the magnetic fillers play a key role in the final heating capability of these nanocomposites. Thus, it has been already reported the improvement of the heating efficiency on Fe3O4 magnetic nanocubes with respect to spherical nanoparticles with the similar mean size1. This result is due to the contribution of the magnetic anisotropy giving rise to higher magnetic coercivity and as consequence, higher SAR (Specific Absorption Rate) values. In this work, well- defined Fe3O4 nanocubes were synthesized through thermal decomposition processes with a mean particle diameter around 70 nm (TEM) (Fig. 1). The SAR values were estimated through the measurement of the AC hysteresis loops, obtaining values of around 900 W/g for the dispersion of the nanocubes in water and values of 350 W/g for the nanocubes dispersed in agar (0.5% wt), with a frequency of 403 kHz and a field amplitude of 30kA/m . In this case, the decrease of the SAR values is due to the inmovilization of the particles in the medium and hence, the Brownian movement of the particles. The temperature increase was also characterized, where a clear enhancement of the heating properties was obtained for nanocubes comparing with spherical nanoparticles of similar mean diameter (Fig. 2). Finally, the heating capacity of the nanocomposites (30% weight of magnetic nanoparticles) was studied through the application of an external AC magnetic field with a Helmholtz coil (319 kHz, 400A, 200G approximately, induction equipment model EasyHeat Ambrell). The effect of the thickness of the polymeric discs on the final temperature achieved was studied (2 and 4 mm thickness and 30 mm diameter). Thus, temperatures of 100 °C or 250 °C were reached after 2 min for the nanocomposites with thicknesses of 2 and 4 mm respectively.
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
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
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
Improved photocatalytic and antibacterial performance of Cr doped TiO2 nanoparticles
(Elsevier, 2021) Gómez Polo, Cristina; Larumbe Abuin, Silvia; Gil Bravo, Antonio; Muñoz Labiano, Delia; Rodríguez Fernández, L.; Fernández Barquín, Luis; García-Prieto, Ana; Fernández-Gubieda, María Luisa; Muela, Alicia; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
The effect of Cr and N doping in the adsorption capacity, photocatalytic properties and antibacterial response of TiO2 anatase nanoparticles is analyzed. The nanoparticles (N-TiO2, Cr-TiO2 and Cr/N-TiO2) were prepared by the sol-gel method. The structural (X-ray diffraction and TEM) and magnetic (SQUID magnetometry) characterization confirms the nanosized nature of the anatase nanoparticles and the absence of secondary phases. The enhancement of the adsorption capacity of the dye (methyl orange) on the surface of the catalysts for the Cr and Cr/N doped samples, together with the redshift of the UV-Vis absorbance spectra promote a high photocatalytic performance under visible light in these nanocatalysts. The culturability and viability of the Escherichia coli DH5α in a medium supplemented with the nanoparticles was characterized and compared with the evolution under visible light (both without and with nanoparticles). The results show that Cr-TiO2 nanoparticles under visible light display antibacterial activity that cannot be accounted by the toxicity of the nanoparticles alone. However the antibacterial effect is not observed in N-TiO2 and Cr/N-TiO2. The differences in the electrostatic charge (isoelectric point) and the degree of nanoparticle dispersion are invoked as the main origins of the different antibacterial response in the Cr-TiO2 nanoparticles.
Open Access
Martensitic transformation controlled by electromagnetic field: from experimental evidence to wireless actuator applications
(Elsevier, 2022) Garayo Urabayen, Eneko; La Roca, Paulo Matías; Gómez Polo, Cristina; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua
Mechanical actuators based on shape memory alloys (SMA) are becoming a key component in the development of novel soft robotic applications and surgically implantable devices. Their working principle relies in the temperature induced martensitic transformation (MT), which is responsible of the actuation mechanism. In this work, we found experimental evidence to show that the martensitic transformation can be controlled by electromagnetic field (EF) by a wireless process in ferromagnetic shape memory alloys. It is shown that the martensitic transformation can be driven by an external EF (frequency 45 kHz) while the specific absorption rate (SAR), which was determined through real-time dynamic magnetization measurements, allows the instantaneous monitoring of the transformation evolution. On the basis of the obtained results, we propose a strategy to achieve a battery-free wireless SMA actuator that can be remotely controlled. This concept can be applicable to other SMA material that exhibit a similar magneto-structural phase transition