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
U-shape magnetostrictive harvester: design and experimental validation
(IEEE, 2024-07-05) Gandía Aguado, David; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Royo Silvestre, Isaac; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Electromagnetic vibrational harvesters stand out due to their high-power density, long-life robust structure and low-cost design. Moreover, they can be designed using magnetostrictive materials. The mechanical vibrations cause stress on the magnetostrictive material, leading to variations in its magnetization. This, in turn, induces an electromotive force (EMF) in a well-designed pick-up coil system, thereby transforming mechanical energy into electrical energy. In spite of the potentiality of these electromagnetic harvesters, their practical implementation is limited due to the difficulties in the design optimization in terms of the device dimensions, effective stresses on the magnetostrive material, distribution and magnetic field strength of the permanent magnets and pick-up coil characteristics. Finite Element Methods (FEM) enable the estimation of the induced voltage and thus the output power as a function of harvester design parameters, allowing us to experiment with different configurations and identify optimal parameters.
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).

Garayo Urabayen, Eneko

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