Authors: Muñetón Arboleda, David; Santillán, Jesica María José; Arce, Valeria B.; Fernández van Raap, Marcela Beatriz; Muraca, Diego; Fernandez, Mariela Alejandra; Torres Sanchez, Rosa Maria; Schinca, Daniel C.; Scaffardi, Lucia Beatriz
Publication Date: 2018.
Language: English.
Abstract:
A comparative study of spectral characteristics, size distribution, composition, morphology and long-term stability of colloidal Ag NPs synthesized by ultrashort pulse laser ablation of a solid target and by chemical salt reduction, both in Trisodium Citrate (TSC) aqueous solution was carried out. Several techniques were independently used to characterize optical, structural and compositional properties of the colloidal samples. Both synthesis routes yield bare core Ag and Ag@Ag2O core@shell NPs, with size distributions of roughly similar size centered at about 1.2 nm radius. Stability analysis of samples was conducted for several weeks and after one-year of fabrication, analyzing the characteristics of the plasmon resonance in the optical extinction spectra and independently by zeta potential measurements. For laser ablation colloids, plasmon peak reaches redshift saturation regime at the second week, while salt reduction colloids seem to reach saturation at times beyond one year. After one year, colloids synthesized by UPLA still show a clear single plasmon resonance in their optical spectra together with higher negative zeta potential values, compatible with very good stability characteristics and no signs of agglomeration. A suitable selection of laser pulse energy and citrate concentration may be used for tuning plasmon resonance peak position and FWHM for specific applications. The biocompatibility properties and good stability of the colloids generated by “green” UPLA may boost its use as long-term antimicrobial additive in films, antifungal paints and antibacterial composites.
Author affiliation: Muñetón Arboleda, David. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina
Author affiliation: Santillán, Jesica María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina
Author affiliation: Arce, Valeria B.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina
Author affiliation: Fernández van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Muraca, Diego. Institute Of Physics Gleb Wataghin; Brasil
Author affiliation: Fernandez, Mariela Alejandra. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina
Author affiliation: Torres Sanchez, Rosa Maria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina
Author affiliation: Schinca, Daniel C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina
Author affiliation: Scaffardi, Lucia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Publication Date: 2004.
Language: English.
Abstract:
AC susceptibility measurements, as a function of temperature and frequency, have been carried out in Y1-xTbxCo2 (0.1 ≤ x ≤ 0.9) compounds to investigate the magnetic phase transition. It is known that YCo2 exhibits very strongly enhanced Pauli paramagnetism, while TbCo2 orders magnetically with a Co moment induced by the Tb molecular field. The phase transition of TbCo2 at 231 K is a second-order phase transition. We found that in Y1-xTb xCo2 the transition changes from first- to second-order as x increases. The increase in the order temperature with Tb concentration is observed and the type of the phase transition is analyzed in the framework of the Inoue-Shimizu model. © 2004 Elsevier B.V. All rights reserved.
Author affiliation: Pasquevich, A. F.. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Fernández van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Forker, M.. Helmholtz Institut für Stralhen und Kernphysik; Alemania
Author affiliation: De La Presa, P.. Helmholtz Institut für Stralhen und Kernphysik; Alemania
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Santillán, Jesica María José; Fernandez Van Raap, Marcela Beatriz; Mendoza Zélis, Pedro; Coral, Diego Fernando; Muraca, Diego; Schinca, Daniel Carlos; Scaffardi, Lucia Beatriz
Publication Date: 2015.
Language: English.
Abstract:
We report for the first time on the formation of self-assembled fractals of spherical Ag nanoparticles (Nps) fabricated by femtosecond pulse laser ablation of a solid silver target in water. Fractal structures grew both in two and three Euclidean dimensions (d). Ramified-fractal assemblies of 2 nm height and 5–14 μm large, decorated with Ag Nps of 3 nm size, were obtained in a 2d geometry when highly diluted drops of colloidal suspension were dried at a fast heating rate over a mica substrate. When less-diluted drops were dried at slow heating rate, isolated single Nps or rosette-like structures were formed. Fractal aggregates about 31 nm size in 3d geometry were observed in the as-prepared colloidal suspension. Electron diffraction and optical extinction spectroscopy (OES) analyses performed on the samples confirmed the presence of Ag and Ag2O. The analysis of the optical extinction spectrum, using the electrostatic approximation of Mie theory for small spheres, showed the existence of Ag bare core, Ag–Ag2O and air–Ag core–shell Nps, Ag–Ag2O being the most frequent type [69 % relative abundance (r.a.)]. Core-size and shell-thickness distribution was derived from OES. In situ scattering measurements of the Ag colloidal suspension, carried out by small-angle X-ray scattering, indicate a mass fractal composed of packaged 〈DSAXS〉 = (5 ± 1) nm particles and fractal dimension df = 2.5. Ex situ atomic force microscopy imaging displayed well-ramified structures, which, analyzed with box-counting method, yield a fractal dimension df = 1.67. The growing behavior of these 2d and 3d self-assembled fractals is consistent with the diffusion-limited aggregation model.
Author affiliation: Santillán, Jesica María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina
Author affiliation: Fernandez Van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Física La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Mendoza Zélis, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentina
Author affiliation: Coral, Diego Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Física La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Muraca, Diego. Universidade Estadual de Campinas; Brasil
Author affiliation: Schinca, Daniel Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentina
Author affiliation: Scaffardi, Lucia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Schinca, Daniel Carlos; Videla, Fabián Alfredo; Fernández Van Raap, Marcela Beatríz; Scaffardi, Lucía Beatríz; Santillán, Jesica María José
Publication Date: 2013.
Language: English.
Abstract:
We report on the analysis of structure, configuration, and sizing of Cu and Cu oxide nanoparticles (Nps) produced by femtosecond (fs) laser ablation of solid copper target in liquids. Laser pulse energy ranged between 500 µJ and 50 µJ. Water and acetone were used to produce the colloidal suspensions. The study was performed through optical extinction spectroscopy using Mie theory to fit the full experimental spectra, considering free and bound electrons size dependent contributions to the metal dielectric function. Raman spectroscopy and AFM technique were also used to characterize the sample. Considering the possible oxidation of copper during the fabrication process, two species (Cu and Cu2O) arranged in two structures (bare core or core-shell) and in two configuration types (Cu-Cu2O or Cu2O-Cu) were considered for the fitting depending on the laser pulse energy and the surrounding media. For water at high energy, it can be observed that a Cu-Cu2O configuration fits the experimental spectra of the colloidal suspension, while for decreasing<br />energy and below a certain threshold, a Cu2O-Cu configuration needs to be included for the<br />optimum fit. Both species coexist for energies below 170 µJ for water. On the other hand, for acetone at high energy, optimum fit of the full spectrum suggests the presence a bimodal Cu-Cu2O core-shell Nps distribution while for decreasing energy and below a 70 µJ threshold energy value, Cu2O-Cu core-shell Nps must be included, together with the former configuration, for the fit of the full spectrum. We discuss possible reasons for the changes in the structural configuration of the core-shell Nps.
Author affiliation: Schinca, Daniel Carlos. Universidad Nacional de la Plata. Facultad de Cs.exactas. Instituto de Fisica de la Plata; Argentina
Author affiliation: Videla, Fabián Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones Opticas (i); Argentina
Author affiliation: Fernández Van Raap, Marcela Beatríz. Universidad Nacional de la Plata. Facultad de Ingenieria; Argentina
Author affiliation: Scaffardi, Lucía Beatríz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones Opticas (i); Argentina
Author affiliation: Santillán, Jesica María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones Opticas (i); Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Fernández van Raap, Marcela Beatriz; Coral, Diego Fernando; Yu, S.; Muñoz Medina, Guillermo Arturo; Sánchez, Francisco Homero; Roig, A.
Publication Date: 2017.
Language: English.
Abstract:
Magnetic hyperthermia, a modality that uses radio frequency heating assisted with single-domain magnetic nanoparticles, is becoming established as a powerful oncological therapy. Much improvement in nanomaterials development, to enhance their heating efficiency by tuning the magnetic colloidal properties, has been achieved. However, methodological standardization to accurately and univocally determine the colloidal properties required to numerically reproduce a specific heating efficiency using analytical expressions still holds. Thus, anticipating the hyperthermic performances of magnetic colloids entails high complexity due to polydispersity, aggregation and dipolar interactions always present in real materials to a greater or lesser degree. Here, by numerically simulating the experimental results and using real biomedical aqueous colloids, we analyse and compare several approaches to reproduce experimental specific absorption rate values. Then, we show that the relaxation time, determined using a representative mean activation energy consistently derived from four independent experiments accurately reproduces experimental heating efficiencies. Moreover, the so-derived relaxation time can be used to extrapolate the heating performance of the magnetic nanoparticles to the other field conditions within the framework of the linear response theory. We thus present a practical tool that may truly aid the design of medical decisions.
Author affiliation: Fernández van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Coral, Diego Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Yu, S.. Consejo Superior de Investigaciones Científicas; España
Author affiliation: Muñoz Medina, Guillermo Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Sánchez, Francisco Homero. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Roig, A.. Consejo Superior de Investigaciones Científicas; España
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: de Sousa, María Elisa; Fernandez Van Raap, Marcela Beatriz; Rivas, Patricia; Mendoza Zélis, Pedro; Girardin, Pablo; Pasquevich, Gustavo Alberto; Alessandrini, José Luis; Muraca, Diego; Sánchez, Francisco Homero
Publication Date: 2013.
Language: English.
Abstract:
Magnetite (Fe3O4) nanoparticles are proper materials for Magnetic Fluid Hyperthermia applications whenever these conjugate stability at physiological (neutral pH) medium and high specific dissipation power. Here, magnetite nanoparticles 9–12 nm in size, electrostatically stabilized by citric acid coating, with hydrodynamic sizes in the range 17–30 nm, and well dispersed in aqueous solution were prepared using a chemical route. The influence of media acidity during the adsorption of citric acid (CA) on the suspension’s long-term stability was systematically investigated. The highest content of nanoparticles in a stable suspension at neutral pH is obtained for coating performed at pH = 4.58, corresponding to the larger amount of CA molecules adsorbed by one carboxylate link. Specific absorption rates (SARs) of various magnetite colloids, determined calorimetrically at a radio frequency field of 265 kHz and field amplitude of 40.1 kA/m, are analyzed in terms of structural and magnetic colloid properties. Larger dipolar interactions lead to larger Néel relaxation times, in some cases larger than Brown relaxation times, which in the present case enhanced magnetic radio frequency heating. The improvement of suspension stability results in a decrease of SAR values, and this decrease is even large in comparison with uncoated magnetite nanoparticles. This fact is related to interactions between particles.
Author affiliation: de Sousa, María Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Fernandez Van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Rivas, Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Mendoza Zélis, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Girardin, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Pasquevich, Gustavo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Alessandrini, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Author affiliation: Muraca, Diego. Universidade Estadual de Campinas; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Author affiliation: Sánchez, Francisco Homero. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Moscoso Londoño, Oscar; Tancredi, PABLO; Muraca, Diego; Mendoza Zélis, Pedro; Coral, Diego Fernando; Fernández van Raap, Marcela Beatriz; Wolff, U.; Neu, V.; Damm, C.; de Oliveira, C.L.P.; Pirota, K.R.; Knobel, Marcelo; Socolovsky, Leandro Martín
Publication Date: 2017.
Language: English.
Abstract:
Controlled magnetic granular materials with different concentrations of magnetite nanoparticles immersed in a non-conducting polymer matrix were synthesized and, their macroscopic magnetic observables analyzed in order to advance towards a better understanding of the magnetic dipolar interactions and its effects on the obtained magnetic parameters. First, by means of X-ray diffraction, transmission electron microscopy, small angle X-ray scattering and X-ray absorption fine structure an accurate study of the structural properties was carried out. Then, the magnetic properties were analyzed by means of different models, including those that consider the magnetic interactions through long-range dipolar forces as: the Interacting Superparamagnetic Model (ISP) and the Vogel-Fulcher law (V-F). In systems with larger nanoparticle concentrations, magnetic results clearly indicate that the role played by the dipolar interactions affects the magnetic properties, giving rise to obtaining magnetic and structural parameters without physical meaning. Magnetic parameters as the effective anisotropic constant, magnetic moment relaxation time and mean blocking temperature, extracted from the application of the ISP model and V-F Law, were used to simulate the zero-field-cooling (ZFC) and field-cooling curves (FC). A comparative analysis of the simulated, fitted and experimental ZFC/FC curves suggests that the current models depict indeed our dilute granular systems. Notwithstanding, for concentrated samples, the ISP model infers that clustered nanoparticles are being interpreted as single entities of larger magnetic moment and volume, effect that is apparently related to a collective and complex magnetic moment dynamics within the cluster.
Author affiliation: Moscoso Londoño, Oscar. Universidade Estadual de Campinas; Brasil
Author affiliation: Tancredi, PABLO. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina
Author affiliation: Muraca, Diego. Universidade Estadual de Campinas; Brasil. Universidade Federal do ABC; Brasil
Author affiliation: Mendoza Zélis, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Coral, Diego Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Fernández van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Wolff, U.. Leibniz Institute for Solid State and Materials Research; Alemania
Author affiliation: Neu, V.. Leibniz Institute for Solid State and Materials Research; Alemania
Author affiliation: Damm, C.. Leibniz Institute for Solid State and Materials Research; Alemania
Author affiliation: de Oliveira, C.L.P.. Universidade de Sao Paulo; Brasil
Author affiliation: Pirota, K.R.. Universidade Estadual de Campinas; Brasil
Author affiliation: Knobel, Marcelo. Universidade Estadual de Campinas; Brasil. Laboratório Nacional de Nanotecnologia; Brasil
Author affiliation: Socolovsky, Leandro Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Sánchez, Francisco Homero; Mendoza Zélis, Pedro; Arciniegas Vaca, Magda Lorena; Pasquevich, Gustavo Alberto; Fernández van Raap, Marcela Beatriz
Publication Date: 2017.
Language: English.
Abstract:
Aiming to analyze relevant aspects of interacting magnetic nanoparticle systems (frequently called interacting superparamagnets), a model is built from magnetic dipolar interaction and demagnetizing mean-field concepts. By making reasonable simplifying approximations, a simple and useful expression for effective demagnetizing factors is achieved, which allows the analysis of uniform and nonuniform spatial distributions of nanoparticles, in particular the occurrence of clustering. This expression is a function of demagnetizing factors associated with specimen shape and clusters shape, and of the mean distances between near neighbor nanoparticles and between clusters, relative to the characteristic sizes of each of these two types of objects, respectively. The model explains effects of magnetic dipolar interactions, such as the observation of apparent nanoparticle magnetic moments smaller than real ones and approaching to zero as temperature decreases. It is shown that by performing a minimum set of experimental determinations along principal directions of geometrically well-defined specimens, model application allows retrieval of nanoparticle intrinsic properties, like mean volume, magnetic moment, and susceptibility in the absence of interactions. It also permits the estimation of mean interparticle and intercluster relative distances, as well as mean values of demagnetizing factors associated with clusters shape. An expression for average magnetic dipolar energy per nanoparticle is also derived, which is a function of specimen effective demagnetizing factor and magnetization. Experimental test of the model was performed by analysis of results reported in the literature and of original results reported here. The first case corresponds to oleic-acid-coated 8-nm magnetite particles dispersed in PEGDA-600 polymer, and the second one to polyacrilic-acid-coated 13-nm magnetite particles dispersed in PVA solutions from which ferrogels were later produced by a physical cross-linking route. In both cases, several specimens were studied covering a range of nanoparticle volume fractions between 0.002 and 0.046. Magnetic response is clearly different when prism-shaped specimens are measured along different principal directions. These results remark the importance of reporting complete information on measurement geometry when communicating magnetic measurement results of interacting magnetic nanoparticles. Intrinsic nanoparticle properties as well as structural information on particles spatial distribution were retrieved from our analysis in addition to, and in excellent agreement with, analysis previously performed by other authors and/or information obtained from FESEM images. In the studied samples, nanoparticles were found to be in close contact to each other within almost randomly oriented clusters. Intercluster mean distance, relative to cluster size, was found to vary between 2.2 and 7.5, depending on particles volume fraction.
Author affiliation: Sánchez, Francisco Homero. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Mendoza Zélis, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Arciniegas Vaca, Magda Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Pasquevich, Gustavo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Fernández van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Coral, Diego Fernando; Mendoza Zélis, Pedro; Marciello, Marzia; Morales, María Del Puerto; Craievich, Aldo; Sánchez, Francisco Homero; Fernández van Raap, Marcela Beatriz
Publication Date: 2016.
Language: English.
Abstract:
Biomedical magnetic colloids commonly used in magnetic hyperthermia experiments often display a bidisperse structure, i.e., are composed of stable nanoclusters coexisting with well-dispersed nanoparticles. However, the influence of nanoclusters in the optimization of colloids for heat dissipation is usually excluded. In this work, bidisperse colloids are used to analyze the effect of nanoclustering and long-range magnetic dipolar interaction on the magnetic hyperthermia efficiency. Two kinds of colloids, composed of magnetite cores with mean sizes of around 10 and 18 nm, coated with oleic acid and dispersed in hexane, and coated with meso-2,3-dimercaptosuccinic acid and dispersed in water, were analyzed. Small-angle X-ray scattering was applied to thoroughly characterize nanoparticle structuring. We proved that the magnetic hyperthermia performances of nanoclusters and single nanoparticles are distinctive. Nanoclustering acts to reduce the specific heating efficiency whereas a peak against concentration appears for the well-dispersed component. Our experiments show that the heating efficiency of a magnetic colloid can increase or decrease when dipolar interactions increase and that the colloid concentration, i.e., dipolar interaction, can be used to improve magnetic hyperthermia. We have proven that the power dissipated by an ensemble of dispersed magnetic nanoparticles becomes a nonextensive property as a direct consequence of the long-range nature of dipolar interactions. This knowledge is a key point in selecting the correct dose that has to be injected to achieve the desired outcome in intracellular magnetic hyperthermia therapy.
Author affiliation: Coral, Diego Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Mendoza Zélis, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Marciello, Marzia. Instituto de Ciencia de Materiales de Madrid; España. Consejo Superior de Investigaciones Científicas; España
Author affiliation: Morales, María Del Puerto. Instituto de Ciencia de Materiales de Madrid; España. Consejo Superior de Investigaciones Científicas; España
Author affiliation: Craievich, Aldo. Universidade de Sao Paulo; Brasil
Author affiliation: Sánchez, Francisco Homero. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Fernández van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Orozco Henao, Juan Manuel; Coral, Diego Fernando; Muraca, Diego; Moscoso Londoño, Oscar; Mendoza Zélis, Pedro; Fernández van Raap, Marcela Beatriz; Sharma, S. K.; Pirota, K.R.; Knobel, Marcelo
Publication Date: 2016.
Language: English.
Abstract:
Magnetohyperthermia properties of magnetic nanoparticle colloids are strongly affected by their intrinsic magnetic properties and dipolar interactions among themselves. The intrinsic magnetic properties are related to the nanoparticle (NP) size, geometry, phase composition, magnetic anisotropy, and saturation magnetization. The dipole-dipole interactions are determined by colloid nanoparticle concentrations and the possible existence of clustering on the colloidal suspension. Here we have observed that oxygen atmosphere and pressure changes during the final stage of thermal decomposition are critical to modify the size of the iron oxide NPs from 8 to near 20 nm, and consequently their overall magnetic properties. Size-dependent magnetic parameters such as anisotropy, magnetic moment per particle, blocking temperature, and dipolar interaction energy were inferred using different phenomenological approaches. A detailed magnetohyperthermia analysis was performed by applying the linear response theory. A good correlation between experimental and theoretical specific absorption rate values was obtained for a frequency of 260 kHz and applied field of 52 kA/m. These results were observed for the different sizes of nanoparticles, and disagreement between the experimental results and the model increases at lower frequencies.
Author affiliation: Orozco Henao, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidade Estadual de Campinas; Brasil
Author affiliation: Coral, Diego Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Muraca, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidade Estadual de Campinas; Brasil
Author affiliation: Moscoso Londoño, Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidade Estadual de Campinas; Brasil
Author affiliation: Mendoza Zélis, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Fernández van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina
Author affiliation: Sharma, S. K.. Federal University of Maranhao; Brasil
Author affiliation: Pirota, K.R.. Universidade Estadual de Campinas; Brasil
Author affiliation: Knobel, Marcelo. Universidade Estadual de Campinas; Brasil. Centro Nacional de Pesquisa em Energia e Materiais; Brasil
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas