Research

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858 KiB

Open AccessArticle

Magnetic Amphiphilic Composites Applied for the Treatment of Biodiesel Wastewaters

by Bruno R. S. Lemos, Ana Paula C. Teixeira, José D. Ardisson, Waldemar A. A. Macedo, Luis E. Fernandez-Outon, Camila C. Amorim, Flávia C. C. Moura and Rochel M. Lago

Appl. Sci. 2012, 2(2), 513-524; https://doi.org/10.3390/app2020513 - 29 May 2012

Cited by 29 | Viewed by 7587

Abstract

In this work, new magnetic amphiphilic composites were prepared by chemical vapor deposition with ethanol on the surface of hydrophilic natural chrysotile matrix containing Fe catalyst. XRD, Raman, Mössbauer and SEM analyses suggest the formation of a complex nanostructured material composed of hydrophobic [...] Read more.

In this work, new magnetic amphiphilic composites were prepared by chemical vapor deposition with ethanol on the surface of hydrophilic natural chrysotile matrix containing Fe catalyst. XRD, Raman, Mössbauer and SEM analyses suggest the formation of a complex nanostructured material composed of hydrophobic carbon nanotubes/nanofibers grown on the hydrophilic surface of the MgSi fiber mineral and the presence of Fe metallic nanoparticles coated by carbon. These nanostructured particles show amphiphilic properties and interact very well with both oil and aqueous phases. When added to emulsions the amphiphilic particles locate on the oil/water interface and, under a magnetic field, the oil droplets collapsed leading to the separation of the aqueous and oil phases. Preliminary work showed excellent results on the use of these particles to break wastewater emulsions in the biodiesel process. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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742 KiB

Open AccessCommunication

Polydimethylsiloxane (PDMS) Coating onto Magnetic Nanoparticles Induced by Attractive Electrostatic Interaction

by Carina Sötebier, Aude Michel and Jérôme Fresnais

Appl. Sci. 2012, 2(2), 485-495; https://doi.org/10.3390/app2020485 - 29 May 2012

Cited by 21 | Viewed by 13319

Abstract

In this article, we present an efficient synthesis pathway of polydimethylsiloxane (PDMS) coated magnetic nanoparticles from hydrophilic polyacrylate coated ferrofluids (NPPAA). A block copolymer based on polydimethylsiloxane is selected for its propensity to interact with the carboxylate functions on the NPPAA. The interaction [...] Read more.

In this article, we present an efficient synthesis pathway of polydimethylsiloxane (PDMS) coated magnetic nanoparticles from hydrophilic polyacrylate coated ferrofluids (NPPAA). A block copolymer based on polydimethylsiloxane is selected for its propensity to interact with the carboxylate functions on the NPPAA. The interaction is due to negative charges on NPPAA and positive ones on the amphiphilic copolymer. The synthesis is achieved by interfacial interaction, simplifying the purification of the PDMS-coated nanoparticles (NPPDMS) from subproducts such as ions and water. NPPDMS are well dispersed in hydrophobic solvents (toluene, diethyl ether) and can then be embedded into a curable PDMS polymer. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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1516 KiB

Open AccessCommunication

A Dual PET/MR Imaging Nanoprobe: ¹²⁴I Labeled Gd₃N@C₈₀

by Jianqiao Luo, John D. Wilson, Jianyuan Zhang, Jerry I. Hirsch, Harry C. Dorn, Panos P. Fatouros and Michael D. Shultz

Appl. Sci. 2012, 2(2), 465-478; https://doi.org/10.3390/app2020465 - 10 May 2012

Cited by 22 | Viewed by 8101

Abstract

The current report describes the development of a dual modality tomographic agent for both positron emission tomography and magnetic resonance imaging (PET/MRI). The dual-modality agent in this study was based on a ¹²⁴I (PET) radiolabeled tri-gadolinium endohedral metallofullerene Gd₃N@C₈₀ [...] Read more.

The current report describes the development of a dual modality tomographic agent for both positron emission tomography and magnetic resonance imaging (PET/MRI). The dual-modality agent in this study was based on a ¹²⁴I (PET) radiolabeled tri-gadolinium endohedral metallofullerene Gd₃N@C₈₀ (MRI) nanoprobe platform. The outer surface of the fullerene cage of the Gd₃N@C₈₀ metallofullerenes was surface functionalized with carboxyl and hydroxyl groups (f-Gd₃N@C₈₀) using previously developed procedures and subsequently iodinated with ¹²⁴I to produce ¹²⁴I-f-Gd₃N@C₈₀nanoprobe. Orthotopic tumor-bearing rats were infused intratumorally by convection-enhanced delivery (CED) with the ¹²⁴I-f-Gd₃N@C₈₀agent and imaged by MRI or micro PET. The anatomical positioning and distribution of the ¹²⁴I-f-Gd₃N@C₈₀agent werecomparable between the MRI and PET scans. The ¹²⁴I-f-Gd₃N@C₈₀dual-agent distribution and infusion site within the tumor was clearly evident in both T₁- and T₂-weighted MR images. The results demonstrate the successful preparation of a dual-modality imaging agent, ¹²⁴I-f-Gd₃N@C₈₀, which could ultimately be used for simultaneous PET/MR imaging. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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396 KiB

Open AccessArticle

Anomalous Magnetization Enhancement and Frustration in the Internal Magnetic Order on (Fe_0.69Co_0.31)B_0.4 Nanoparticles

by Belén Molina-Concha, Roberto D. Zysler and Héctor Romero

Appl. Sci. 2012, 2(2), 315-326; https://doi.org/10.3390/app2020315 - 02 Apr 2012

Cited by 6 | Viewed by 7177

Abstract

We have studied the internal magnetic order of 3-nm (Fe_0.69Co_0.31)_0.6B_0.4 amorphous nanoparticles. These nanoparticles were dispersed in a non-magnetic matrix (non-interacting nanoparticles) to contrast them with the powder samples, where strong interparticle interactions are present. In [...] Read more.

We have studied the internal magnetic order of 3-nm (Fe_0.69Co_0.31)_0.6B_0.4 amorphous nanoparticles. These nanoparticles were dispersed in a non-magnetic matrix (non-interacting nanoparticles) to contrast them with the powder samples, where strong interparticle interactions are present. In similar fashion to the bulk alloy, this system exhibits a saturation magnetization maximum as a function of Fe composition near 69 at% Fe for the powder and dispersed samples at all temperatures. The saturation magnetization (M_S) of the dispersed sample shows anomalous behavior, revealing frustration in the internal magnetic order of the particles. Unexpectedly, the M_S of the non-interacting sample at low temperatures is larger than the corresponding bulk alloy or the calculated value of M_S for the same Fe-Co composition. By contrast, the powder sample has low M_S values and it is approximately constant in temperature. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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3244 KiB

Open AccessArticle

Effects of Superparamagnetic Nanoparticle Clusters on the Polymerase Chain Reaction

by Toshiaki Higashi, Hiroaki Minegishi, Yutaka Nagaoka, Takahiro Fukuda, Akinobu Echigo, Ron Usami, Toru Maekawa and Tatsuro Hanajiri

Appl. Sci. 2012, 2(2), 303-314; https://doi.org/10.3390/app2020303 - 02 Apr 2012

Cited by 15 | Viewed by 7185

Abstract

The polymerase chain reaction (PCR) method is widely used for the reproduction and amplification of specific DNA segments, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the effects of superparamagnetic nanoparticles on [...] Read more.

The polymerase chain reaction (PCR) method is widely used for the reproduction and amplification of specific DNA segments, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the effects of superparamagnetic nanoparticles on PCR amplification without an external magnetic field, and clarifies the mechanism behind the effects of superparamagnetic particle clusters on PCR efficiency by estimating the structures of such clusters in PCR. It was found that superparamagnetic nanoparticles tend to inhibit PCR amplification depending on the structure of the magnetic nanoparticle clusters. The paper also clarifies that Taq polymerase is captured in the spaces formed among magnetic nanoparticle clusters, and that it is captured more efficiently as a result of their motion from heat treatment in PCR thermal cycles. Consequently, Taq polymerase that should be used in PCR is reduced in the PCR solution. These outcomes will be applied to novel PCR techniques using magnetic particles in an external magnetic field. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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1377 KiB

Open AccessArticle

Magnetically Separable Base Catalysts: Heterogeneous Catalysis vs. Quasi-Homogeneous Catalysis

by Raed Abu-Reziq and Howard Alper

Appl. Sci. 2012, 2(2), 260-276; https://doi.org/10.3390/app2020260 - 26 Mar 2012

Cited by 21 | Viewed by 8544

Abstract

The synthesis of magnetically separable quasi-homogeneous base catalyst and heterogeneous base catalyst is described. The quasi-homogeneous catalyst is achieved by supporting silane monomers functionalized with different amine groups directly on the surface of magnetite nanoparticles. The heterogeneous catalyst is prepared via [...] Read more.

The synthesis of magnetically separable quasi-homogeneous base catalyst and heterogeneous base catalyst is described. The quasi-homogeneous catalyst is achieved by supporting silane monomers functionalized with different amine groups directly on the surface of magnetite nanoparticles. The heterogeneous catalyst is prepared via a sol-gel process in which silane monomers containing different amine groups are copolymerized with tetraethoxysilane in the presence of magnetite nanoparticles functionalized with ionic liquid moieties. The reactivity of the quasi-homogeneous and the heterogeneous base catalysts is compared in the nitroaldol condensation. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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574 KiB

Open AccessArticle

2D Spin-Dependent Diffraction of Electrons From Periodical Chains of Nanomagnets

by Teshome Senbeta and Vadim N. Mal’nev

Appl. Sci. 2012, 2(1), 220-232; https://doi.org/10.3390/app2010220 - 06 Mar 2012

Cited by 1 | Viewed by 5579

Abstract

The scattering of the unpolarized beams of electrons by nanomagnets in the vicinity of some scattering angles leads to complete spin polarized electrons. This result is obtained with the help of the perturbation theory. The dipole-dipole interaction between the magnetic moment of the [...] Read more.

The scattering of the unpolarized beams of electrons by nanomagnets in the vicinity of some scattering angles leads to complete spin polarized electrons. This result is obtained with the help of the perturbation theory. The dipole-dipole interaction between the magnetic moment of the nanomagnet and the magnetic moment of electron is treated as perturbation. This interaction is not spherically symmetric. Rather it depends on the electron spin variables. It in turn results in spinor character of the scattering amplitudes. Due to the smallness of the magnetic interactions, the scattering length of this process is very small to be proved experimentally. To enhance the relevant scattering lengths, we considered the diffraction of unpolarized beams of electrons by linear chains of nanomagnets. By tuning the distance between the scatterers it is possible to obtain the diffraction maximum of the scattered electrons at scattering angles which corresponds to complete spin polarization of electrons. It is shown that the total differential scattering length is proportional to N² (N is a number of scatterers). Even small number of nanomagnets in the chain helps to obtain experimentally visible enhancement of spin polarization of the scattered electrons. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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Review

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1278 KiB

Open AccessReview

Magnetic Nanoparticles in the Imaging of Tumor Angiogenesis

by Shaunagh McDermott and Alexander R. Guimaraes

Appl. Sci. 2012, 2(2), 525-534; https://doi.org/10.3390/app2020525 - 29 May 2012

Cited by 8 | Viewed by 7134

Abstract

Angiogenesis, the growth of new capillary blood vessels, is central to the growth of tumors. Non-invasive imaging of tumor angiogenesis will allow for earlier detection of tumors and also the development of surrogate markers for assessing response to treatment. Steady state magnetic resonance [...] Read more.

Angiogenesis, the growth of new capillary blood vessels, is central to the growth of tumors. Non-invasive imaging of tumor angiogenesis will allow for earlier detection of tumors and also the development of surrogate markers for assessing response to treatment. Steady state magnetic resonance imaging with magnetic nanoparticles is one method to assess angiogenesis. In this article we explain the theory behind steady state magnetic resonance imaging and review the available literature. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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6427 KiB

Open AccessReview

Ion Beam Formation and Modification of Cobalt Nanoparticles

by David J. Sprouster and Mark C. Ridgway

Appl. Sci. 2012, 2(2), 396-442; https://doi.org/10.3390/app2020396 - 27 Apr 2012

Cited by 24 | Viewed by 8036

Abstract

This article reviews the size-dependent structural properties of ion beam synthesized Co nanoparticles (NPs) and the influence of ion irradiation on the size, shape, phase and structure. The evolution of the aforementioned properties were determined using complementary laboratory- and advanced synchrotron-based techniques, including [...] Read more.

This article reviews the size-dependent structural properties of ion beam synthesized Co nanoparticles (NPs) and the influence of ion irradiation on the size, shape, phase and structure. The evolution of the aforementioned properties were determined using complementary laboratory- and advanced synchrotron-based techniques, including cross-sectional transmission electron microscopy, small-angle X-ray scattering and X-ray absorption spectroscopy. Combining such techniques reveals a rich array of transformations particular to Co NPs. This methodology highlights the effectiveness of ion implantation and ion irradiation procedures as a means of fine tuning NP properties to best suit specific technological applications. Furthermore, our results facilitate a better understanding and aid in identifying the underlying physics particular to this potentially technologically important class of nanomaterials. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)

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