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7 results on '"Bruvera, I. J."'

1. Raiders of the lost SAR: Radiofrequency cycles of magnetic nanoflowers inside a tumor

Author

Bruvera, I. J., Actis, D. G., Soto, P., Blank, V., Roguin, L., van Raap, M. B. Fernandez, and Zelis, P. Mendoza

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Radiofrequency magnetic cycles of \textit{ex vivo} melanoma tumor tissue loaded with Fe$_3$O$_4$ nanoflowers (NF) were measured for several field conditions and compared with the cycles of a ferrogel (FG) obtained incorporating identical NF in agarose gel. Results were studied in order to understand a reported specific power dissipation (SAR) reduction of the NF in the actual application medium (tumor) in comparison with a typical characterization model as the FG. The linearity of the response, together with coercive field and SAR values were analyzed.\\ Additionally, a novel method for the determination of the NF mean relaxation time is presented. Results show a systematic difference in magnetic response between the NF incorporated in the tumor and those in the FG for all field settings (\{98, 170, 260\} kHz and \{17.4, 54.0\} kA/m) with SAR reductions above 50\%.

Published
2021
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2. Novel multifunctional 90Y-labelled albumin magnetic microspheres for cancer therapy

Author

Vranješ-\Djurić, S., Radović, M., Nikolić, N., Janković, D., Goya, G. F., Torres, T. E., Calatayud, M. P., Bruvera, I. J., Ibarra, M. R., Spasojević, V., Jancar, B., and Antić, B.

Subjects
Quantitative Biology - Tissues and Organs, Condensed Matter - Materials Science, Physics - Medical Physics
Abstract

We present in vitro and in vivo studies of yttrium-90 (90Y)-labelled human serum albumin magnetic microspheres (HSAMMS) as multifunctional agent for bimodal radionuclide-hyperthermia cancer therapy. The HSAMMS were produced using a modified emulsification-heat stabilization technique and contained 10-nm magnetite nanoparticles coated with citric acid, distributed as inhomogeneous clusters within the albumin microspheres. The average particle size of the complete HSAMMS was 20 (mu)m, and they exhibited superparamagnetic behavior at room temperature. The stability of the 90^Y-labelled HSAMMS was investigated in vitro (in saline and human serum) and in vivo by analyzing their biodistribution in normal Wistar rats. The in vitro experiments revealed the high stability of the labelled HSAMMS in saline and human serum after 72 h. Following the intravenous administration of the 90^Y-HSAMMS in rats, 88.81% of the activity localizes in the lungs after 1 h, with 82.67% remaining after 72 h. These data on 90Y-HSAMMS provide good evidence for their potential use in bimodal radionuclide-hyperthermia cancer therapy., Comment: 27 pages, 9 figures, submitted to Acta Biomateriala

Published
2012
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3. An integrated device for magnetically-driven drug release and in situ quantitative measurements: Design, fabrication and testing

Author

Bruvera, I. J., Hernández, Rebeca, Mijangos, Carmen, Goya, G. F., Bruvera, I. J., Hernández, Rebeca, Mijangos, Carmen, and Goya, G. F.

Abstract

We have developed a device capable of remote triggering and in situ quantification of therapeutic drugs, based on magnetically-responsive hydrogels of poly (N-isopropylacrylamide) and alginate (PNiPAAm). The heating efficiency of these hydrogels measured by their specific power absorption (SPA) values showed that the values between 100 and 300 W/g of the material were high enough to reach the lower critical solution temperature (LCST) of the polymeric matrix within few minutes. The drug release through application of AC magnetic fields could be controlled by time-modulated field pulses in order to deliver the desired amount of drug. Using B12 vitamin as a concept drug, the device was calibrated to measure amounts of drug released as small as 25(2) × 10-9 g, demonstrating the potential of this device for very precise quantitative control of drug release.

Published
2015

5. Specific Power Absorption of silica-coated magnetite cubes

Author

Marcelo, Gema, Catalina, Fernando, Bruvera, I. J., Marquina, Clara, Goya, Gerardo F., Marcelo, Gema, Catalina, Fernando, Bruvera, I. J., Marquina, Clara, and Goya, Gerardo F.

Abstract

We have developed silica stabilized ferrimagnetic magnetite nanocubes (MNCs) as effective heat mediators for magnetic hyperthermia. To do that, large hydrophobic magnetite nanoparticles, with a mean size of 79 and 124 nm were synthesized and transferred to water by silica surface modification. The heating ability of these water suspensions was studied by measuring the Specific Power Absorption (SPA) applying an AC magnetic field of amplitude H0 = 45 kA/m and frequency f = 360 kHz. High SPA values were obtained, ranging from 560 to 1160 W/g. The normalization of the SPA values by the inverse of the frequency and squared field amplitude was performed in order to compare our results with these described in literature. The SPA value for our samples, normalized in this way, yielded values of 0.7-1.5 nH m2/kg.

Published
2014

7. Structural and magnetic study of zinc-doped magnetite nanoparticles and ferrofluids for hyperthermia applications.

Author

Mendoza Zélis, P., Pasquevich, G. A., Stewart, S. J., Fernández van Raap, M. B., Aphesteguy, J., Bruvera, I. J., Laborde, C., Pianciola, B., Jacobo, S., and Sánchez, F. H.

Subjects
MAGNETIC properties of nanoparticles, MAGNETIC fluids, FEVER, PRECIPITATION (Chemistry), MAGNETIZATION
Abstract

Cubic-like shaped ZnxFe3-xO4 particles with crystallite mean sizes D between 15 and 117 nm were obtained by co-precipitation. Particle size effects and preferential occupation of spinel tetrahedral site by Zn2+ ions led to noticeable changes of physical properties. D ⩾ 30 nm particles displayed nearly bulk properties, which were dominated by Zn concentration. For D ⩽ 30 nm, dominant magnetic relaxation effects were observed by Mössbauer spectroscopy, with the mean blocking size DB ~ 13 to 15 nm. Saturation magnetization increased with x up to x ~ 0.1-0.3 and decreased for larger x. Power absorbed by water and chitosan-based ferrofluids from a 260 kHz radio frequency field was measured as a function of x, field amplitude H0 and ferrofluid concentration. For H0 = 41 kA m-1 the maximum specific absorption rate was 367Wg-1 for D = 16 nm and x = 0.1. Absorption results are interpreted within the framework of the linear response theory for H0 ⩽ 41 kA m-1. A departure towards a saturation regime was observed for higher fields. Simulations based on a two-level description of nanoparticle magnetic moment relaxation qualitatively agree with these observations. The frequency factor of the susceptibility dissipative component, derived from experimental results, showed a sharp maximum at D ~ 16 nm. This behaviour was satisfactorily described by simulations based on moment relaxation processes, which furthermore indicated a crossover from Néel to Brown mechanisms at D ~ 18 nm. Hints for further improvement of magnetite particles as nanocalefactors for magnetic hyperthermia are discussed. [ABSTRACT FROM AUTHOR]

Published
2013
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