Examinando por Autor "Mantovani, Diego"

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Modulation of Crystallinity through Radiofrequency Electromagnetic Fields in PLLA/Magnetic Nanoparticles Composites: A Proof of Concept
(MDPI, 2021-07-31) Multigner, Marta; Morales, Irene; Muñoz, Marta; Bonache, Victoria; Giacomone, Fernando; de la Presa, Patricia; Benavente, Rosario; Torres, Belén; Mantovani, Diego; Rams, Joaquín
To modulate the properties of degradable implants from outside of the human body represents a major challenge in the field of biomaterials. Polylactic acid is one of the most used polymers in biomedical applications, but it tends to lose its mechanical properties too quickly during degradation. In the present study, a way to reinforce poly-L lactic acid (PLLA) with magnetic nanoparticles (MNPs) that have the capacity to heat under radiofrequency electromagnetic fields (EMF) is proposed. As mechanical and degradation properties are related to the crystallinity of PLLA, the aim of the work was to explore the possibility of modifying the structure of the polymer through the heating of the reinforcing MNPs by EMF within the biological limit range f H < 5 10^9 Am-1s-1. Composites were prepared by dispersing MNPs under sonication in a solution of PLLA. The heat released by the MNPs was monitored by an infrared camera and changes in the polymer were analyzed with differential scanning calorimetry and nanoindentation techniques. The crystallinity, hardness, and elastic modulus of nanocomposites increase with EMF treatment.
Study of the effect of magnetic fields on static degradation of Fe and Fe-12Mn-1.2C in balanced salts modified Hanks’ solution
(Elsevier, 2024-06-29) Limón, Irene; Multigner, Marta; Paternoster, Carlo; Lieblich, Marcela; Torres, Belén; Mantovani, Diego; Rams, Joaquín
Iron and its alloys are attractive as biodegradable materials because of their low toxicity and suitable mechanical properties; however, they generally have a slow degradation rate. Given that corrosion is an electrochemical phenomenon where an exchange of electrons takes place, the application of magnetic fields from outside the body may accelerate the degradation of a ferrous temporary implant. In the present study, we have investigated the effect of alternating and direct low magnetic field (H = 6.5 kA/m) on the corrosion process of pure iron (Fe) and an iron-manganese alloy (FeMnC) in modified Hanks´ solution. A 14-day static immersion test was performed on the materials. The corrosion rate was assessed by mass and cross-sectional loss measurements, scanning electron microscopy, X-ray diffractometry, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy before and after degradation. The results show that the presence of magnetic fields significantly accelerates the degradation rate of both materials, with the corrosion rate being twice as high in the case of Fe and almost three times as high for FeMnC. In addition, a homogenous degradation layer is formed over the entire surface and the chemical composition of the degradation products is the same regardless of the presence of a magnetic field.