FMR and SMFMR study of Fe/Si multilayers

In this paper the investigations of magnetic and magnetoelastic properties of Fe/Si multilayers are presented. The multilayers have been grown by de sputtering on the single - crystal GaAs substrates. Ferromagnetic resonance (FMR) measurements were performed at the frequency of 9.4 GHz and in the temperature range from liquid helium to room temperature before and after illumination with 514nm light. The magnetostriction constant of investigated films has been measured at room temperature by strain modulated ferromagnetic resonance (SMFMR) method. An attention is given to the effect of the interface on the observed effective saturation magnetostriction. The FMR and SMFMR measurements mostly revealed the contribution from interface to the observed spectra. The results were analyzed taking into account both the alloying effects and the intrinsic surface anisotropy and magnetostriction. It was show that in the case of Fe/Si multilayers the effect of alloying prevails

Effect of Neutron Irradiation on the EPR Spectra of CuGeO3\text{}_{3}

The influence of neutron irradiation on the electron paramagnetic resonance spectra of the spin-Peierls compound CuGeO$\text{}_{3}$ was investigated in the wide temperature range 2-300 K. It was found that the irradiation induced appreciable changes in the EPR signal intensity, resonance line width and g-factor of this material. It was also shown that the irradiation leads to a decrease in the spin-Peierls transition temperature. For higher irradiation doses, an antiferromagnetically ordered phase can be observed at lower temperatures. This phase coexists with the spin-Peierls phase. The observed decrease in the spin-Peierls transition temperature after irradiation may be associated with some changes in topological and chemical short-range order or with the transmutation of the fraction of $\text{}^{63}$Cu in the $\text{}^{63}$Cu(n,α)$\text{}^{60}$Co reaction

Effect of Heavy Ion Irradiation on the Magnetic Properties of CuGeO3\text{}_{3}

The influence of heavy ion irradiation on the magnetic properties of the spin-Peierls compound CuGeO$\text{}_{3}$ has been investigated by means of the electron paramagnetic resonance, the spontaneous magnetization, and the low field ac susceptibility. The measurements were performed on the CuGeO$\text{}_{3}$ single crystals before and after irradiation with 80 MeV oxygen ions in the wide temperature range of 2-300 K. It was found that the irradiation induced an increase in the EPR signal intensity, magnetization, and susceptibility of this material. It was also shown that the irradiation does not lead to a decrease in the spin-Peierls transition temperature and to the formation of an antiferromagnetic phase which is expected to appear in disordered spin-Peierls systems

Synthesis and magnetic characterization of Pb(1-x)Mn(x)S nanocrystals in glass matrix

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The synthesis of manganese-doped PbS (Pb(1-x)Mn(x)S) nanocrystal (NC) dots within a borosilicate glass matrix has been investigated by atomic force microscopy, electron paramagnetic resonance and magnetic measurements. The fusion method was employed in the preparation of the magnetic semiconductor NC dots whereas the measurements performed showed changes in the physical properties of the manganese-doped dots as a result of the Mn(2+)-incorporation into the hosting PbS crystal structure. Nevertheless, the data indicated that only a small fraction of the nominal Mn-doping was incorporated into the PbS NC dot, in both lower (0.5%) and higher (40%) nominal doping ends. For the lower nominal Mn-doping end (0.5%) we found only about 0.05% actually incorporated into the PbS NC dot whereas about 0.45% appeared dispersed throughout the glass template as isolated paramagnetic centres.4116Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)FINATECConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Selol-loaded magnetic nanocapsules: A new approach for hyperthermia cancer therapy

Polylactic-co-glycolic nanocapsules, loaded with nanosized magnetic particles and Selol (a selenium-based anticancer drug), were successfully prepared by the precipitation method. Maghemite (gamma-Fe(2)O(3)) nanoparticles were incorporated into the nanocapsules using a highly stable ionic magnetic fluid sample. The obtained nanocapsules presented no agglomeration, negative surface charge while revealing a narrow monomodal size distribution. All the nanocapsule formulations exhibited a good physical stability at 4 degrees C during 3 month storage period. The in vitro antitumoral activity of Selol-magnetic nanocapsules was assessed using a murine melanoma cell line. The influence of nanocapsules on cell viability was investigated by spectrophotometric assay. The results demonstrated that Selol-loaded magnetic nanocapsules (at 100 mu g/ml/5 x 10(9) particle/ml) showed antitumoral activity of 50% on melanoma cells (absence of magnetic field). These results clearly indicate that the loaded nanocapsules represent a novel and promising magnetic drug delivery system suitable for cancer treatment via the active drug and magnetohyperthermia. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3556950

Co-nanoencapsulation of magnetic nanoparticles and selol for breast tumor treatment: in vitro evaluation of cytotoxicity and magnetohyperthermia efficacy

Luciana LC Estevanato,1 Jaqueline R Da Silva,1 André M Falqueiro,2 Ewa Mosiniewicz-Szablewska,3 Piotr Suchocki,4,5 Antônio C Tedesco,2 Paulo C Morais,6 Zulmira GM Lacava11Instituto de Ciências Biológicas, Universidade de Brasília, Brasília DF, Brazil; 2Departamento de Química, Laboratório de Fotobiologia e Fotomedicina, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto SP, Brazil; 3Institute of Physics, Polish Academy of Sciences, Warsaw, Poland; 4Department of Drug Analysis, Warsaw Medical University, Warsaw, Poland; 5Department of Pharmaceutical Chemistry, National Medicines Institute, Warsaw, Poland; 6Instituto de Física, Universidade de Brasília, Brasília DF, BrazilAbstract: Antitumor activities have been described in selol, a hydrophobic mixture of molecules containing selenium in their structure, and also in maghemite magnetic nanoparticles (MNPs). Both selol and MNPs were co-encapsulated within poly(lactic-co-glycolic acid) (PLGA) nanocapsules for therapeutic purposes. The PLGA-nanocapsules loaded with MNPs and selol were labeled MSE-NC and characterized by transmission and scanning electron microscopy, electrophoretic mobility, photon correlation spectroscopy, presenting a monodisperse profile, and positive charge. The antitumor effect of MSE-NC was evaluated using normal (MCF-10A) and neoplastic (4T1 and MCF-7) breast cell lines. Nanocapsules containing only MNPs or selol were used as control. MTT assay showed that the cytotoxicity induced by MSE-NC was dose and time dependent. Normal cells were less affected than tumor cells. Cell death occurred mainly by apoptosis. Further exposure of MSE-NC treated neoplastic breast cells to an alternating magnetic field increased the antitumor effect of MSE-NC. It was concluded that selol-loaded magnetic PLGA-nanocapsules (MSE-NC) represent an effective magnetic material platform to promote magnetohyperthermia and thus a potential system for antitumor therapy.Keywords: PLGA-nanocapsule, cancer, maghemite nanoparticle, MTT, drug delivery, seleniu

In vitro cytotoxicity of Selol-loaded magnetic nanocapsules against neoplastic cell lines under AC magnetic field activation

The goals of this study are to evaluate in vitro compatibility of magnetic nanomaterials and their therapeutic potential against cancer cells. Highly stable ionic magnetic fluid sample (maghemite, gamma-Fe2O3) and Selol were incorporated into polymeric nanocapsules by nanoprecipitation method. The cytotoxic effect of Selol-loaded magnetic nanocapsules was assessed on murine melanoma (B16-F10) and oral squamous cell carcinoma (OSCC) cell lines following AC magnetic field application. The influence of different nanocapsules on cell viability was investigated by colorimetric MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. In the absence of AC magnetic field Selol-loaded magnetic nanocapsules, containing 100 mu g/mL Selol plus 5 x 10(12) particle/mL, showed antitumoral activity of about 50% on B16-F10 melanoma cells while OSCC carcinoma cells demonstrated drug resistance at all concentrations of Selol and magnetic fluid (range of 100-500 mu g/mL Selol and 5 x 10(12) -2.5 x 10(13) particle/mL). On the other hand, under AC applied fields (1 MHz and 40 Oe amplitude) B16-F10 cell viability was reduced down to 40.5% (+/- 3.33) at the highest concentration of nanoencapsulated Selol. The major effect, however, was observed on OSCC cells since the cell viability drops down to about 33.3% (+/- 0.38) under application of AC magnetic field. These findings clearly indicate that the Selol-loaded magnetic nanocapsules present different toxic effects on neoplastic cell lines. Further, the cytotoxic effect was maximized under AC magnetic field application on OSCC, which emphasizes the effectiveness of the magnetohyperthermia approach. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3680541]FAPESPFAPESP [09/13208-3, 07/55319-0, 08/53719-4]CNPqCNPq [573880/2008-5, 09/15363-6, 07/588099]Polish State Committee for Scientific ResearchPolish State Committee for Scientific Research [N N405 360639, N N202 166440