BCMaterials Fortnightly Seminars #16

“Magnetic transition induced by mechanical deformation in Fe₆₀Al_40-xSi_x ternary alloys” 

Estibaliz Legarra

(BCMaterials)

Mechanical deformation is known to induce disorder in completely ordered Fe-Al alloys. This effect produces a strong increase in the magnetic properties of these alloys and may even induce ferromagnetic transition in ordered paramagnetic alloys. We have used Mössbauer spectroscopy and X-ray diffraction to study the influence of different Al/Si ratios on the structural and magnetic properties of the mechanically deformed Fe₆₀Al_{40_x}Si_x alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe₆₀Al₄₀ alloys. Besides, Si introduction has two opposite contributions. From a structural point of view, hinders the disordering process, but, from a magnetic point of view promotes the magnetic transition.

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“Biomedical applications of Ni_0.31Fe_2.69O₄@CS magnetic nanospheres”

Xabier Lasheras

(BCMaterials / Instituto de Nanociencia de Aragón)

Magnetic nanosystems are being one of the principal investigation areas over the last years, and many of actual research works are concentrate on improve and optimize these systems in order to develop new therapies and diagnosis ways to treat different diseases, but specially conducted to diagnosis and treatment of different cancer. In order to use this materials in biomedical applications is necessary to transfer the nanoparticles to water media and make them stable in physiological conditions to maintain the colloidal stability during in vivo treatments. Nowadays, many research works are directed to make that surface modification by encapsulation of nanoparticles into a biocompatible polymer, obtaining homogeneous nanoparticle aggregates into this polymer with diameters between 50-500 nm. This is an interesting option since more than stabilize our nanoparticles in biological media with biopolymers, the controlled encapsulation process give the opportunity to modify the properties of obtained magnetic nanospheres changing the interactions between nanoparticles. Biopolysacharides as chitosan are currently documented for developing long circulating systems. It is one of the most used polymer for biomedical applications because of its biocompatibility, biodegradability, low cost and cationic properties. Large microspheres and beads have typically been used for the prolonged release of drugs and tissue engineering. For these reasons, this study is focused on encapsulation of magnetic nanoparticles into chitosan nanospheres and in vitro and in vivo studies of these stability and biocompatibility in order to use them in future applications as MRI and drug delivery. These test have been done with 100 nm nanospheres encapsulation nickel ferrite nanoparticles and Nile red hydrophobic fluorophore.