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Special Issue "Magnetic Nanoparticles 2015"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Materials Science".

Deadline for manuscript submissions: closed (30 June 2015).

Special Issue Editor

Dr. O. Thompson Mefford
Website
Guest Editor
Department of Materials Science and Engineering, 161 Sirrine Hall, Clemson University, Clemson, SC 29634-0971, USA

Special Issue Information

Dear Colleagues,

Magnetic nanoparticles are one of the most exciting classes of nanomateials. These particles can be produced in a non-toxic form, functionalized with a wide range of stabilizing and specialized moieties, and are true field responsive materials. Biomedical applications include diagnostic tools such as imaging and cellular viscosity measurements, therapeutic procedures including magnetic field hyperthermia, and delivery applications such as drug delivery and gene transfection. Moreover, the relative non-response of the body to applied magnetic field is well suited for these applications over alternatives such as optical or electrical stimuli. Over the past few decades, scientists have produced the first generation of these particle systems with relatively simple core-shell particle-polymer structures, with initial results suggesting the great potential of these materials. Recently, more sophisticated models have included targeted receptors, temperature responsive materials, and better understanding of the physics of the stimuli-response of these materials. This issue will cover a variety of topics related to the use of magnetic nanoparticles in biomedicine, and examine both novel synthesis and functionalization techniques, as well as their current and future uses in biomedical research, diagnostics and therapy.

Dr. O. Thompson Mefford
Guest Editor

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Keywords

  • magnetic nanoparticles
  • biomedical
  • diagnostics
  • imaging
  • therapy

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Published Papers (18 papers)

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Open AccessArticle
Exposure to Iron Oxide Nanoparticles Coated with Phospholipid-Based Polymeric Micelles Induces Biochemical and Histopathological Pulmonary Changes in Mice
Int. J. Mol. Sci. 2015, 16(12), 29417-29435; https://doi.org/10.3390/ijms161226173 - 10 Dec 2015
Cited by 12
Abstract
The biochemical and histopathological changes induced by the exposure to iron oxide nanoparticles coated with phospholipid-based polymeric micelles (IONPs-PM) in CD-1 mice lungs were analyzed. After 2, 3, 7 and 14 days following the intravenous injection of IONPs-PM (5 and 15 mg Fe/kg [...] Read more.
The biochemical and histopathological changes induced by the exposure to iron oxide nanoparticles coated with phospholipid-based polymeric micelles (IONPs-PM) in CD-1 mice lungs were analyzed. After 2, 3, 7 and 14 days following the intravenous injection of IONPs-PM (5 and 15 mg Fe/kg bw), lactate dehydrogenase (LDH) activity, oxidative stress parameters and the expression of Bax, Bcl-2, caspase-3 and TNF-α were evaluated in lung tissue. An increase of catalase (CAT) and glutathione reductase (GR) activities on the second day followed by a decrease on the seventh day, as well as a decline of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity on the third and seventh day were observed in treated groups vs. controls. However, all these enzymatic activities almost fully recovered on the 14th day. The reduced glutathione (GSH) and protein thiols levels decreased significantly in nanoparticles-treated groups and remained diminished during the entire experimental period; by contrast malondialdehyde (MDA) and protein carbonyls increased between the 3rd and 14th day of treatment vs. control. Relevant histopathological modifications were highlighted using Hematoxylin and Eosin (H&E) staining. In addition, major changes in the expression of apoptosis markers were observed in the first week, more pronounced for the higher dose. The injected IONPs-PM generated a dose-dependent decrease of the mouse lung capacity, which counteracted oxidative stress, thus creating circumstances for morphopathological lesions and oxidation processes. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Gold-Coated Superparamagnetic Nanoparticles for Single Methyl Discrimination in DNA Aptamers
Int. J. Mol. Sci. 2015, 16(11), 27625-27639; https://doi.org/10.3390/ijms161126046 - 18 Nov 2015
Cited by 8
Abstract
Au- and iron-based magnetic nanoparticles (NPs) are promising NPs for biomedical applications due to their unique properties. The combination of a gold coating over a magnetic core puts together the benefits from adding the magnetic properties to the robust chemistry provided by the [...] Read more.
Au- and iron-based magnetic nanoparticles (NPs) are promising NPs for biomedical applications due to their unique properties. The combination of a gold coating over a magnetic core puts together the benefits from adding the magnetic properties to the robust chemistry provided by the thiol functionalization of gold. Here, the use of Au-coated magnetic NPs for molecular detection of a single methylation in DNA aptamer is described. Binding of α-thrombin to two aptamers conjugated to these NPs causes aggregation, a phenomenon that can be observed by UV, DLS and MRI. These techniques discriminate a single methylation in one of the aptamers, preventing aggregation due to the inability of α-thrombin to recognize it. A parallel study with gold and ferromagnetic NPs is detailed, concluding that the Au coating of FexOy NP does not affect their performance and that they are suitable as complex biosensors. These results prove the high detection potency of Au-coated SPIONs for biomedical applications especially for DNA repair detection. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Development of Ferromagnetic Superspins in Bare Cu Nanoparticles by Electronic Charge Redistribution
Int. J. Mol. Sci. 2015, 16(10), 23165-23176; https://doi.org/10.3390/ijms161023165 - 24 Sep 2015
Cited by 5
Abstract
We report on the results of investigating the ferromagnetic properties of bare Cu nanoparticles. Three sets of bare Cu nanoparticle assemblies with mean particle diameters of 6.6, 8.1, and 11.1 nm were fabricated, employing the gas condensation method. Curie-Weiss paramagnetic responses to a [...] Read more.
We report on the results of investigating the ferromagnetic properties of bare Cu nanoparticles. Three sets of bare Cu nanoparticle assemblies with mean particle diameters of 6.6, 8.1, and 11.1 nm were fabricated, employing the gas condensation method. Curie-Weiss paramagnetic responses to a weak driving magnetic field were detected, showing the appearance of particle superspins that overcomes the diamagnetic responses from the inner core. The isothermal magnetization displays a Langevin field profile together with magnetic hysteresis appearing even at 300 K, demonstrating the existence of ferromagnetic superspins in the Cu nanoparticles. Shifting of a noticeable amount of electronic charge from being distributed near the lattice sites in bulk form toward their neighboring ions in nanoparticles was found. The extended 3d and 4s band mixture are the main sources for the development of localized 3d holes for the development of ferromagnetic particle superspins in Cu nanoparticles. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Classification of Magnetic Nanoparticle Systems—Synthesis, Standardization and Analysis Methods in the NanoMag Project
Int. J. Mol. Sci. 2015, 16(9), 20308-20325; https://doi.org/10.3390/ijms160920308 - 27 Aug 2015
Cited by 38
Abstract
This study presents classification of different magnetic single- and multi-core particle systems using their measured dynamic magnetic properties together with their nanocrystal and particle sizes. The dynamic magnetic properties are measured with AC (dynamical) susceptometry and magnetorelaxometry and the size parameters are determined [...] Read more.
This study presents classification of different magnetic single- and multi-core particle systems using their measured dynamic magnetic properties together with their nanocrystal and particle sizes. The dynamic magnetic properties are measured with AC (dynamical) susceptometry and magnetorelaxometry and the size parameters are determined from electron microscopy and dynamic light scattering. Using these methods, we also show that the nanocrystal size and particle morphology determines the dynamic magnetic properties for both single- and multi-core particles. The presented results are obtained from the four year EU NMP FP7 project, NanoMag, which is focused on standardization of analysis methods for magnetic nanoparticles. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Huge Inverse Magnetization Generated by Faraday Induction in Nano-Sized [email protected] [email protected] Nanoparticles
Int. J. Mol. Sci. 2015, 16(9), 20139-20151; https://doi.org/10.3390/ijms160920139 - 25 Aug 2015
Cited by 2
Abstract
We report on the design and observation of huge inverse magnetizations pointing in the direction opposite to the applied magnetic field, induced in nano-sized amorphous Ni shells deposited on crystalline Au nanoparticles by turning the applied magnetic field off. The magnitude of the [...] Read more.
We report on the design and observation of huge inverse magnetizations pointing in the direction opposite to the applied magnetic field, induced in nano-sized amorphous Ni shells deposited on crystalline Au nanoparticles by turning the applied magnetic field off. The magnitude of the induced inverse magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before turning the magnetic field off, and can be as high as 54% of the magnetization prior to cutting off the applied magnetic field. Memory effect of the induced inverse magnetization is clearly revealed in the relaxation measurements. The relaxation of the inverse magnetization can be described by an exponential decay profile, with a critical exponent that can be effectively tuned by the wait time right after reaching the designated temperature and before the applied magnetic field is turned off. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Exploiting Size-Dependent Drag and Magnetic Forces for Size-Specific Separation of Magnetic Nanoparticles
Int. J. Mol. Sci. 2015, 16(8), 20001-20019; https://doi.org/10.3390/ijms160820001 - 21 Aug 2015
Cited by 10
Abstract
Realizing the full potential of magnetic nanoparticles (MNPs) in nanomedicinerequires the optimization of their physical and chemical properties. Elucidation of the effectsof these properties on clinical diagnostic or therapeutic properties, however, requires thesynthesis or purification of homogenous samples, which has proved to be [...] Read more.
Realizing the full potential of magnetic nanoparticles (MNPs) in nanomedicinerequires the optimization of their physical and chemical properties. Elucidation of the effectsof these properties on clinical diagnostic or therapeutic properties, however, requires thesynthesis or purification of homogenous samples, which has proved to be difficult. Whileinitial simulations indicated that size-selective separation could be achieved by flowingmagnetic nanoparticles through a magnetic field, subsequent in vitro experiments wereunable to reproduce the predicted results. Magnetic field-flow fractionation, however, wasfound to be an effective method for the separation of polydisperse suspensions of iron oxidenanoparticles with diameters greater than 20 nm. While similar methods have been used toseparate magnetic nanoparticles before, no previous work has been done with magneticnanoparticles between 20 and 200 nm. Both transmission electron microscopy (TEM) anddynamic light scattering (DLS) analysis were used to confirm the size of the MNPs. Furtherdevelopment of this work could lead to MNPs with the narrow size distributions necessary fortheir in vitro and in vivo optimization. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Magnetic Nanoparticle Arrays Self-Assembled on Perpendicular Magnetic Recording Media
Int. J. Mol. Sci. 2015, 16(8), 19769-19779; https://doi.org/10.3390/ijms160819769 - 20 Aug 2015
Cited by 5
Abstract
We study magnetic-field directed self-assembly of magnetic nanoparticles onto templates recorded on perpendicular magnetic recording media, and quantify feature width and height as a function of assembly time. Feature widths are determined from Scanning Electron Microscope (SEM) images, while heights are obtained with [...] Read more.
We study magnetic-field directed self-assembly of magnetic nanoparticles onto templates recorded on perpendicular magnetic recording media, and quantify feature width and height as a function of assembly time. Feature widths are determined from Scanning Electron Microscope (SEM) images, while heights are obtained with Atomic Force Microscopy (AFM). For short assembly times, widths were ~150 nm, while heights were ~14 nm, a single nanoparticle on average with a 10:1 aspect ratio. For long assembly times, widths approach 550 nm, while the average height grows to 3 nanoparticles, ~35 nm; a 16:1 aspect ratio. We perform magnetometry on these self-assembled structures and observe the slope of the magnetic moment vs. field curve increases with time. This increase suggests magnetic nanoparticle interactions evolve from nanoparticle–nanoparticle interactions to cluster–cluster interactions as opposed to feature–feature interactions. We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media. If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Polymer/Iron Oxide Nanoparticle Composites—A Straight Forward and Scalable Synthesis Approach
Int. J. Mol. Sci. 2015, 16(8), 19752-19768; https://doi.org/10.3390/ijms160819752 - 20 Aug 2015
Cited by 11
Abstract
Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in [...] Read more.
Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
DNA Targeting Sequence Improves Magnetic Nanoparticle-Based Plasmid DNA Transfection Efficiency in Model Neurons
Int. J. Mol. Sci. 2015, 16(8), 19369-19386; https://doi.org/10.3390/ijms160819369 - 17 Aug 2015
Cited by 10
Abstract
Efficient non-viral plasmid DNA transfection of most stem cells, progenitor cells and primary cell lines currently presents an obstacle for many applications within gene therapy research. From a standpoint of efficiency and cell viability, magnetic nanoparticle-based DNA transfection is a promising gene vectoring [...] Read more.
Efficient non-viral plasmid DNA transfection of most stem cells, progenitor cells and primary cell lines currently presents an obstacle for many applications within gene therapy research. From a standpoint of efficiency and cell viability, magnetic nanoparticle-based DNA transfection is a promising gene vectoring technique because it has demonstrated rapid and improved transfection outcomes when compared to alternative non-viral methods. Recently, our research group introduced oscillating magnet arrays that resulted in further improvements to this novel plasmid DNA (pDNA) vectoring technology. Continued improvements to nanomagnetic transfection techniques have focused primarily on magnetic nanoparticle (MNP) functionalization and transfection parameter optimization: cell confluence, growth media, serum starvation, magnet oscillation parameters, etc. Noting that none of these parameters can assist in the nuclear translocation of delivered pDNA following MNP-pDNA complex dissociation in the cell’s cytoplasm, inclusion of a cassette feature for pDNA nuclear translocation is theoretically justified. In this study incorporation of a DNA targeting sequence (DTS) feature in the transfecting plasmid improved transfection efficiency in model neurons, presumably from increased nuclear translocation. This observation became most apparent when comparing the response of the dividing SH-SY5Y precursor cell to the non-dividing and differentiated SH-SY5Y neuroblastoma cells. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment
Int. J. Mol. Sci. 2015, 16(8), 19291-19307; https://doi.org/10.3390/ijms160819291 - 14 Aug 2015
Cited by 16
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEONLA-BSA, which were synthesized using excess albumin. For optimization of magnetic treatment applications, [...] Read more.
Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEONLA-BSA, which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEONLA-BSA particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEONLA-BSA changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Overexpression of the MRI Reporter Genes Ferritin and Transferrin Receptor Affect Iron Homeostasis and Produce Limited Contrast in Mesenchymal Stem Cells
Int. J. Mol. Sci. 2015, 16(7), 15481-15496; https://doi.org/10.3390/ijms160715481 - 08 Jul 2015
Cited by 33
Abstract
Imaging technologies that allow the non-invasive monitoring of stem cells in vivo play a vital role in cell-based regenerative therapies. Recently, much interest has been generated in reporter genes that enable simultaneous monitoring of the anatomical location and viability of cells using magnetic [...] Read more.
Imaging technologies that allow the non-invasive monitoring of stem cells in vivo play a vital role in cell-based regenerative therapies. Recently, much interest has been generated in reporter genes that enable simultaneous monitoring of the anatomical location and viability of cells using magnetic resonance imaging (MRI). Here, we investigate the efficacy of ferritin heavy chain-1 (Fth1) and transferrin receptor-1 (TfR1) as reporters for tracking mesenchymal stem cells. The overexpression of TfR1 was well tolerated by the cells but Fth1 was found to affect the cell’s iron homeostasis, leading to phenotypic changes in the absence of iron supplementation and an upregulation in transcript and protein levels of the cell’s endogenous transferrin receptor. Neither the sole overexpression of Fth1 nor TfR1 resulted in significant increases in intracellular iron content, although significant differences were seen when the two reporter genes were used in combination, in the presence of high concentrations of iron. The supplementation of the culture medium with iron sources was a more efficient means to obtain contrast than the use of reporter genes, where high levels of intracellular iron were reflected in transverse (T2) relaxation. The feasibility of imaging iron-supplemented cells by MRI is shown using a 3R-compliant chick embryo model. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
In Vivo Molecular MRI Imaging of Prostate Cancer by Targeting PSMA with Polypeptide-Labeled Superparamagnetic Iron Oxide Nanoparticles
Int. J. Mol. Sci. 2015, 16(5), 9573-9587; https://doi.org/10.3390/ijms16059573 - 28 Apr 2015
Cited by 25
Abstract
The prostate specific membrane antigen (PSMA) is broadly overexpressed on prostate cancer (PCa) cell surfaces. In this study, we report the synthesis, characterization, in vitro binding assay, and in vivo magnetic resonance imaging (MRI) evaluation of PSMA targeting superparamagnetic iron oxide nanoparticles (SPIONs). [...] Read more.
The prostate specific membrane antigen (PSMA) is broadly overexpressed on prostate cancer (PCa) cell surfaces. In this study, we report the synthesis, characterization, in vitro binding assay, and in vivo magnetic resonance imaging (MRI) evaluation of PSMA targeting superparamagnetic iron oxide nanoparticles (SPIONs). PSMA-targeting polypeptide CQKHHNYLC was conjugated to SPIONs to form PSMA-targeting molecular MRI contrast agents. In vitro studies demonstrated specific uptake of polypeptide-SPIONs by PSMA expressing cells. In vivo MRI studies found that MRI signals in PSMA-expressing tumors could be specifically enhanced with polypeptide-SPION, and further Prussian blue staining showed heterogeneous deposition of SPIONs in the tumor tissues. Taken altogether, we have developed PSMA-targeting polypeptide-SPIONs that could specifically enhance MRI signal in tumor-bearing mice, which might provide a new strategy for the molecular imaging of PCa. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Different Storage Conditions Influence Biocompatibility and Physicochemical Properties of Iron Oxide Nanoparticles
Int. J. Mol. Sci. 2015, 16(5), 9368-9384; https://doi.org/10.3390/ijms16059368 - 24 Apr 2015
Cited by 34
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted increasing attention in many biomedical fields. In magnetic drug targeting SPIONs are injected into a tumour supplying artery and accumulated inside the tumour with a magnet. The effectiveness of this therapy is thus dependent on magnetic [...] Read more.
Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted increasing attention in many biomedical fields. In magnetic drug targeting SPIONs are injected into a tumour supplying artery and accumulated inside the tumour with a magnet. The effectiveness of this therapy is thus dependent on magnetic properties, stability and biocompatibility of the particles. A good knowledge of the effect of storage conditions on those parameters is of utmost importance for the translation of the therapy concept into the clinic and for reproducibility in preclinical studies. Here, core shell SPIONs with a hybrid coating consisting of lauric acid and albumin were stored at different temperatures from 4 to 45 °C over twelve weeks and periodically tested for their physicochemical properties over time. Surprisingly, even at the highest storage temperature we did not observe denaturation of the protein or colloidal instability. However, the saturation magnetisation decreased by maximally 28.8% with clear correlation to time and storage temperature. Furthermore, the biocompatibility was clearly affected, as cellular uptake of the SPIONs into human T-lymphoma cells was crucially dependent on the storage conditions. Taken together, the results show that the particle properties undergo significant changes over time depending on the way they are stored. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Enzymatic Synthesis of Magnetic Nanoparticles
Int. J. Mol. Sci. 2015, 16(4), 7535-7550; https://doi.org/10.3390/ijms16047535 - 03 Apr 2015
Cited by 9
Abstract
We report the first in vitro enzymatic synthesis of paramagnetic and antiferromagnetic nanoparticles toward magnetic ELISA reporting. With our procedure, alkaline phosphatase catalyzes the dephosphorylation of l-ascorbic-2-phosphate, which then serves as a reducing agent for salts of iron, gadolinium, and holmium, forming magnetic [...] Read more.
We report the first in vitro enzymatic synthesis of paramagnetic and antiferromagnetic nanoparticles toward magnetic ELISA reporting. With our procedure, alkaline phosphatase catalyzes the dephosphorylation of l-ascorbic-2-phosphate, which then serves as a reducing agent for salts of iron, gadolinium, and holmium, forming magnetic precipitates of Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5. The nanoparticles were found to be paramagnetic at 300 K and antiferromagnetic under 25 K. Although weakly magnetic at 300 K, the room-temperature magnetization of the nanoparticles found here is considerably greater than that of analogous chemically-synthesized LnxFeyOz (Ln = Gd, Ho) samples reported previously. At 5 K, the nanoparticles showed a significantly higher saturation magnetization of 45 and 30 emu/g for Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5, respectively. Our approach of enzymatically synthesizing magnetic labels reduces the cost and avoids diffusional mass-transfer limitations associated with pre-synthesized magnetic reporter particles, while retaining the advantages of magnetic sensing. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Functionalization of Magnetite Nanoparticles as Oil Spill Collector
Int. J. Mol. Sci. 2015, 16(4), 6911-6931; https://doi.org/10.3390/ijms16046911 - 26 Mar 2015
Cited by 46
Abstract
In the present study, a new magnetic powder based on magnetite can be used as a petroleum crude oil collector. Amidoximes based on rosin as a natural product can be prepared from a reaction between hydroxylamine and rosin/acrylonitrile adducts. The produced rosin amidoximes [...] Read more.
In the present study, a new magnetic powder based on magnetite can be used as a petroleum crude oil collector. Amidoximes based on rosin as a natural product can be prepared from a reaction between hydroxylamine and rosin/acrylonitrile adducts. The produced rosin amidoximes were used as capping agents for magnetite nanoparticles to prepare hydrophobic coated magnetic powders. A new class of monodisperse hydrophobic magnetite nanoparticles was prepared by a simple and inexpensive co-precipitation method. Iron ions and iodine were prepared by the reaction between ferric chloride and potassium iodide. The structure and morphology of magnetite capped with rosin amidoxime were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), zeta potential, thermogravimetric analysis (TGA) and dynamic light scattering (DLS). The magnetic properties were determined from vibrating sample magnetometer (VSM) analyses. These prepared magnetite nanoparticles were tested as bioactive nanosystems and their antimicrobial effects were investigated. The prepared nanomaterials were examined as a crude oil collector using magnetic fields. The results show promising data for the separation of the petroleum crude oil from aqueous solution in environmental pollution cleanup. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessArticle
Biocompatible PEGylated Fe3O4 Nanoparticles as Photothermal Agents for Near-Infrared Light Modulated Cancer Therapy
Int. J. Mol. Sci. 2014, 15(10), 18776-18788; https://doi.org/10.3390/ijms151018776 - 17 Oct 2014
Cited by 35
Abstract
In accordance with the World Cancer Report, cancer has become the leading cause of mortality worldwide, and various therapeutic strategies have been developed at the same time. In the present study, biocompatible magnetic nanoparticles were designed and synthesized as high-performance photothermal agents for [...] Read more.
In accordance with the World Cancer Report, cancer has become the leading cause of mortality worldwide, and various therapeutic strategies have been developed at the same time. In the present study, biocompatible magnetic nanoparticles were designed and synthesized as high-performance photothermal agents for near-infrared light mediated cancer therapy in vitro. Via a facile one-pot solvothermal method, well-defined PEGylated magnetic nanoparticles (PEG–Fe3O4) were prepared with cheap inhesion as a first step. Due to the successful coating of PEG molecules on the surface of PEG–Fe3O4, these nanoparticles exhibited excellent dispersibility and dissolvability in physiological condition. Cytotoxicity based on MTT assays indicated these nanoparticles revealed high biocompatibility and low toxicity towards both Hela cells and C6 cells. After near-infrared (NIR) laser irradiation, the viabilities of C6 cells were effectively suppressed when incubated with the NIR laser activated PEG–Fe3O4. In addition, detailed photothermal anti-cancer efficacy was evaluated via visual microscope images, demonstrating that our PEG–Fe3O4 were promising for photothermal therapy of cancer cells. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Review

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Open AccessReview
Biomedical Applications of Magnetically Functionalized Organic/Inorganic Hybrid Nanofibers
Int. J. Mol. Sci. 2015, 16(6), 13661-13677; https://doi.org/10.3390/ijms160613661 - 15 Jun 2015
Cited by 25
Abstract
Nanofibers are one-dimensional nanomaterial in fiber form with diameter less than 1 µm and an aspect ratio (length/diameter) larger than 100:1. Among the different types of nanoparticle-loaded nanofiber systems, nanofibers loaded with magnetic nanoparticles have gained much attention from biomedical scientists due to [...] Read more.
Nanofibers are one-dimensional nanomaterial in fiber form with diameter less than 1 µm and an aspect ratio (length/diameter) larger than 100:1. Among the different types of nanoparticle-loaded nanofiber systems, nanofibers loaded with magnetic nanoparticles have gained much attention from biomedical scientists due to a synergistic effect obtained from the unique properties of both the nanofibers and magnetic nanoparticles. These magnetic nanoparticle-encapsulated or -embedded nanofiber systems can be used not only for imaging purposes but also for therapy. In this review, we focused on recent advances in nanofibers loaded with magnetic nanoparticles, their biomedical applications, and future trends in the application of these nanofibers. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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Open AccessReview
Iron Oxide Nanoparticles for Magnetically-Guided and Magnetically-Responsive Drug Delivery
Int. J. Mol. Sci. 2015, 16(4), 8070-8101; https://doi.org/10.3390/ijms16048070 - 10 Apr 2015
Cited by 205
Abstract
In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and magnetofection. In magnetically-guided nanoparticles, a constant external magnetic field is used to transport magnetic nanoparticles loaded with drugs to a [...] Read more.
In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and magnetofection. In magnetically-guided nanoparticles, a constant external magnetic field is used to transport magnetic nanoparticles loaded with drugs to a specific site within the body or to increase the transfection capacity. Magnetofection is the delivery of nucleic acids under the influence of a magnetic field acting on nucleic acid vectors that are associated with magnetic nanoparticles. In magnetically-responsive nanoparticles, magnetic nanoparticles are encapsulated or embedded in a larger colloidal structure that carries a drug. In this last case, an alternating magnetic field can modify the structure of the colloid, thereby providing spatial and temporal control over drug release. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2015)
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