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
Fast calculation methods for the magnetic field of particle lattices
(AIP Publishing, 2025-02-14) Royo Silvestre, Isaac; Gandía Aguado, David; Beato López, Juan Jesús; Garayo Urabayen, Eneko; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
With the rise of 3D printing and composite materials, components comprising dispersed magnetic particles have become more interesting due to the possibility to design magnetic elements of any shape with varying amounts of the actual magnetic material. However, quick and easy calculation methods are needed to design these components enabling the selection of the optimum required percentage of magnetic particles (millimeter parts contain billions of micro-sized particles). This work proposes a semi-analytical iterative method for the estimation of the magnetic field generated by magnetic composites formed by embedded magnetic particles. The model is compared in terms of accuracy and calculation speed with finite element analysis and the average magnetization model of the magnetic composite. The results are finally supported by the comparison with experimental measurements of the weak magnetic field generated by a magnetic particle lattice.
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
Non-linear GMI decoding in 3D printed magnetic encoded systems
(Elsevier, 2023) Beato López, Juan Jesús; Algueta-Miguel, Jose M.; Galarreta Rodríguez, Itziar; Garayo Urabayen, Eneko; López Ortega, Alberto; 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; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The nonlinear giant magnetoimpedance (GMI) effect was explored as a highly sensitive sensing technology in 3D-printed magnetic encoded systems. Magnetic nanoparticles with low (magnetite, Fe3O4) and high (Co ferrite, Co0.7Fe2.3O4) magnetic remanence were embedded (10 wt%) in a polymeric matrix of Polylactic Acid (PLA) and Poly-ε-caprolactone (PCL) and extruded in magnetic filaments to be 3D printed by the Fused Deposition Modelling technique (FDM). Two different geometries were constructed namely, individual magnetic strips and fixed barcoded pieces. The stray magnetic fields generated by the magnetic nanoparticles were detected through the non-linear (second harmonic) GMI voltage using a soft magnetic CoFeSiB wire as the nucleus sensor. The decoding response was analyzed as a function of the magnetization remanence of the nanoparticles, the distance between the individual magnetic strips, and the position (height) of the GMI decoding sensor. It has been shown that modification of the net magnetization direction of each individual fixed strip within the barcode geometry is possible through the application of local external magnetic fields. This possibility improves the versatility of the 3D binary encoding system by adding an additional state (0 without nanoparticles, 1 or −1 depending on the relative orientation of the net magnetization along the strips) during the codifying procedure.
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
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
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
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
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
Magnetically activated 3D printable polylactic acid/polycaprolactone/magnetite composites for magnetic induction heating generation
(Springer, 2023) Galarreta Rodríguez, Itziar; López Ortega, Alberto; Garayo Urabayen, Eneko; Beato López, Juan Jesús; La Roca, Paulo Matías; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; 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
Additive manufacturing technology has attracted the attention of industrial and technological sectors due to the versatility of the design and the easy manufacture of structural and functional elements based on composite materials. The embedding of magnetic nanoparticles in the polymeric matrix enables the development of an easy manufacturing process of low-cost magnetically active novel polymeric composites. In this work, we report a series of magnetic composites prepared by solution casting method combining 5 to 60 wt.% of 140 ± 50 nm commercial Fe3O4 nanoparticles, with a semi-crystalline, biocompatible, and biodegradable polymeric blend made of polylactic acid (PLA) and polycaprolactone (PCL). The composites were extruded, obtaining 1.5 ± 0.2 mm diameter continuous and flexible filaments for fused deposition modelling 3D printing. The chemical, magnetic, and calorimetric properties of the obtained filaments were investigated by differential scanning calorimetry, thermogravimetric analysis, magnetometry, and scanning electron microscopy. Furthermore, taking advantage of the magnetic character of the filaments, their capability to generate heat under the application of low-frequency alternating magnetic fields (magnetic induction heating) was analyzed. The obtained results expose the versatility of these easy manufacturing and low-cost filaments, where selecting a desired composition, the heating capacity can be properly adjusted for those applications where magnetic induction plays a key role (i.e., magnetic hyperthermia, drug release, heterogeneous catalysis, water electrolysis, gas capture, or materials synthesis).