Multiferroic Behavior of Templated BiFeO₃–CoFe₂O₄ Self-Assembled Nanocomposites

Self-assembled BiFeO₃–CoFe₂O₄ nanocomposites were templated into ordered structures in which the ferrimagnetic CoFe₂O₄ pillars form square arrays of periods 60–100 nm in a ferroelectric BiFeO₃ matrix. The ferroelectricity, magnetism, conductivity, and magnetoelectric coupling of the ordered nanocomposites were characterized by scanning probe microscopy. The insulating BiFeO₃ matrix exhibited ferroelectric domains, whereas the resistive CoFe₂O₄ pillars exhibited single-domain magnetic contrast with high anisotropy due to the magnetoelasticity of the spinel phase. Magnetoelectric coupling was observed in which an applied voltage led to reversal of the magnetic pillars

Inhibition of Neurofilament and Shank2 Expression by Bevacizumab in Differentiated Retinoblastoma Cells.

<p>(A, B) SNUOT-Rb1 cells were treated with 0.1% BSA or 1 mg/ml bevacizumab. Neurofilament (A) and shank2 (B) were detected by Western blot analysis. β-actin was served as a loading control. Each figure is representative ones from three independent experiments. Quantitative analysis was performed by measuring protein expression relative to the controls. Each value represents means ± SE from three independent experiments (*P<0.05). BSA, bovine serum albumin. (C) SNUOT-Rb1 cells were treated with 0.1% BSA or 1 mg/ml bevacizumab. Neuronal differentiation was addressed by the morphological changes of neurite extensions. Immunocytochemistry for neurofilament (green) and shank2 (red) was performed, and nuclei were labeled with DAPI (blue). Each figure is representative ones from three independent experiments. Scale bar, 20 µm. DAPI, 4′, 6-diamidino-2-phenolindole. (D) SNUOT-Rb1 cells were treated with 0.1% BSA, 1 mg/ml human IgG, or 1 mg/ml bevacizumab. Neurite length in differentiated retinoblastoma cells was measured by manual tracing of neurite outgrowth in each cell. Quantitative analysis was performed using average length from total neurites measured. Each value represents means ± SE from three independent experiments (*P<0.05, **P>0.05). (E, F, G) Retinoblastoma cells of SNUOT-Rb1 (E) and Y79 (F, G) were treated with either 0.1% BSA or 1 mg/ml human IgG. Total mRNA was isolated from retinoblastoma cells, and reverse transcriptase-polymerase chain reaction was performed with specific primers for neurofilament or shank2. GAPDH was served as an internal control. Each figure is representative ones from three independent experiments. Quantitative analysis was performed by measuring mRNA expression relative to the control. Each value represents means ± SE from three independent experiments (*P<0.05, **P>0.05).</p

Bevacizumab-induced Inhibition of Differentiation of Retinoblastoma Cells through Blockade of ERK 1/2 Activation.

<p>SNUOT-Rb1 cells were treated with 0.1% BSA or 1 mg/ml bevacizumab. ERK 1/2, phospho-ERK 1/2, Akt, and phospho-Akt were detected by Western blot analysis. β-actin was served as a loading control. Each figure is representative ones from three independent experiments. Quantitative analysis was performed by measuring protein expression relative to the controls. Each value represents means ± SE from three independent experiments (*P<0.05, **P>0.05). BSA, bovine serum albumin.</p

Activation of TrkA Induced by VEGF in Retinoblastoma Cells.

<p>(A) Proteins of human retinoblastoma cell lines, Y79 and SNUOT-Rb1 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033456#pone.0033456-Kim5" target="_blank">[22]</a> as well as a human colorectal cancer cell lines, SW480 were resolved on 12% SDS-PAGE and western blot analysis was performed using anti-TrkA antibody. β-actin was served as a loading control. Each figure is representative ones from three independent experiments. (B) Proteins of Y79 and SNUOT-Rb1 cells were resolved on 12% SDS-PAGE and western blot analysis was performed using anti-VEGFR-2 and anti-TrkA antibody. β-actin was served as a loading control. Each figure is representative ones from three independent experiments. (C) SNUOT-Rb1 cells were treated with 10 ng/ml VEGF. TrkA and phospho-TrkA were detected by Western blot analysis. β-actin was served as a loading control. Each figure is representative ones from three independent experiments.</p

Combinatorial Pulsed Laser Deposition of Fe, Cr, Mn, and Ni-Substituted SrTiO₃ Films on Si Substrates

Combinatorial pulsed laser deposition (CPLD) using two targets was used to produce a range of transition metal-substituted perovskite-structured Sr­(Ti_1–<i>x</i>M_<i>x</i>)­O_3−δ films on buffered silicon substrates, where M = Fe, Cr, Ni and Mn and <i>x</i> = 0.05–0.5. CPLD produced samples whose composition vs distance fitted a linear combination of the compositions of the two targets. Sr­(Ti_1–<i>x</i>Fe_<i>x</i>)­O_3−δ films produced from a pair of perovskite targets (SrTiO₃ and SrFeO₃ or SrTiO₃ and SrTi0_0.575Fe_0.425O₃) had properties similar to those of films produced from single targets, showing a single phase microstructure, a saturation magnetization of 0.5 μ_B/Fe, and a strong out-of-plane magnetoelastic anisotropy at room temperature. Films produced from an SrTiO₃ and a metal oxide target consisted of majority perovskite phases with additional metal oxide (or metal in the case of Ni) phases. Films made from SrTiO₃ and Fe₂O₃ targets retained the high magnetic anisotropy of Sr­(Ti_1–<i>x</i>Fe_<i>x</i>)­O_3−δ, but had a much higher saturation magnetization than single-target films, reaching for example an out-of-plane coercivity of >2 kOe and a saturation magnetization of 125 emu/cm³ at 24%Fe. This was attributed to the presence of maghemite or magnetite exchange-coupled to the Sr­(Ti_1–<i>x</i>Fe_<i>x</i>)­O_3−δ. Films of Sr­(Ti_1–<i>x</i>Cr_<i>x</i>)­O_3−δ and Sr­(Ti_1–<i>x</i>Mn_<i>x</i>)­O_3−δ showed no room temperature ferromagnetism, but Sr­(Ti_1–<i>x</i>Ni_<i>x</i>)­O_3−δ did show a high anisotropy and magnetization attributed mainly to the perovskite phase. Combinatorial synthesis is shown to be an efficient process for enabling evaluation of the properties of epitaxial substituted perovskite films as well as multiphase films which have potential for a wide range of electronic, magnetic, optical, and catalytic applications

Magnetic Phase Formation in Self-Assembled Epitaxial BiFeO₃–MgO and BiFeO₃–MgAl₂O₄ Nanocomposite Films Grown by Combinatorial Pulsed Laser Deposition

Self-assembled epitaxial BiFeO₃–MgO and BiFeO₃–MgAl₂O₄ nanocomposite thin films were grown on SrTiO₃ substrates by pulsed laser deposition. A two-phase columnar structure was observed for BiFeO₃–MgO codeposition within a small window of growth parameters, in which the pillars consisted of a magnetic spinel phase (Mg,Fe)₃O₄ within a BiFeO₃ matrix, similar to the growth of BiFeO₃–MgFe₂O₄ nanocomposites reported elsewhere. Further, growth of a nanocomposite with BiFeO₃–(CoFe₂O₄/MgO/MgFe₂O₄), in which the minority phase was grown from three different targets, gave spinel pillars with a uniform (Mg,Fe,Co)₃O₄ composition due to interdiffusion during growth, with a bifurcated shape from the merger of neighboring pillars. BiFeO₃–MgAl₂O₄ did not form a well-defined vertical nanocomposite in spite of having lower lattice mismatch, but instead formed a two-phase film with in which the spinel phase contained Fe. These results illustrate the redistribution of Fe between the oxide phases during oxide codeposition to form a ferrimagnetic phase from antiferromagnetic or nonmagnetic targets

Magnetic and Photoluminescent Coupling in SrTi_0.87Fe_0.13O_3−δ/ZnO Vertical Nanocomposite Films

Self-assembled growth of SrTi_0.87Fe_0.13O_3−δ (STF)/ZnO vertical nanocomposite films by combinatorial pulsed laser deposition is described. The nanocomposite films form vertically aligned columnar epitaxial nanostructures on SrTiO₃ substrates, in which the STF shows room-temperature magnetism. The magnetic properties are discussed in terms of strain states, oxygen vacancies, and microstructures. The nanocomposites exhibit magneto-photoluminescent coupling behavior that the near-band-edge emission of ZnO is shifted as a function of magnetic field

Hierarchical Templating of a BiFeO₃–CoFe₂O₄ Multiferroic Nanocomposite by a Triblock Terpolymer Film

A process route to fabricate templated BiFeO₃/CoFe₂O₄ (BFO/CFO) vertical nanocomposites is presented in which the self-assembly of the BFO/CFO is guided using a self-assembled triblock terpolymer. A linear triblock terpolymer was selected instead of a diblock copolymer in order to produce a square-symmetry template, which had a period of 44 nm. The triblock terpolymer pattern was transferred to a (001) Nb:SrTiO₃ substrate to produce pits that formed preferential sites for the nucleation of CFO crystals, in contrast to the BFO, which wetted the flat regions of the substrate. The crystallographic orientation and magnetic properties of the templated BFO/CFO were characterized