scholarly journals A new route of emulsifier-free emulsion polymerization for the preparation of polymer coated magnetite nanoparticles

2014 ◽  
Vol 32 (2) ◽  
pp. 264-271 ◽  
Author(s):  
Q. Nguyen ◽  
D. Quyen ◽  
T. Hoang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Emulsion Polymerization ◽  
Magnetic Particles ◽  
Mass Ratio ◽  
Transmission Electron ◽  
Magnetization Saturation ◽  
Polymer Thickness ◽  
Polymer Layer Thickness

AbstractA new route of emulsifier-free emulsion polymerization based on the homogenous mechanism was investigated to prepare magnetic nanoparticles coated by poly (methyl methacrylate) (PMMA). The experimental results confirm the formation of PMMA thin and unique layers covering magnetite cores. The polymer layer thickness, determined from transmission electron microscopy (TEM) images, increases from 4.3 nm to 6.8 nm with increasing mass ratio of MMA to magnetite from 3:1 to 11:1. The increase of the polymer thickness results in the decrease in magnetization saturation of polymeric coated magnetic particles. However, this reduction, no more than 13 emu g−1, is much lower compared to that in other studies with the presence of surfactants or emulsifiers. Besides, the dispersion stability of the prepared particles is significantly improved.

Real-Space Transmission Electron Microscopy Investigations of Attachment of Functionalized Magnetic Nanoparticles to DNA-Coils Acting as a Biosensor

2010 ◽  
Vol 114 (41) ◽  
pp. 13255-13262 ◽  
Author(s):  
Sultan Akhtar ◽  
Mattias Strömberg ◽  
Teresa Zardán Gómez de la Torre ◽  
Camilla Russell ◽  
Klas Gunnarsson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Real Space ◽  
Transmission Electron ◽  
Functionalized Magnetic Nanoparticles

Preparation of Size and Morphology Controlled Gold Nanoparticles in Micro-Emulsion and in Aqueous

2012 ◽  
Vol 184-185 ◽  
pp. 1138-1141
Author(s):  
Yan Biao Zhang ◽  
Xiao Hui Zhang ◽  
Hong Zong Yin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Light Scattering ◽  
Homogeneous Distribution ◽  
Mass Ratio ◽  
Optimum Ratio ◽  
Transmission Electron ◽  
Micro Emulsion ◽  
Size And Morphology

In this study, we prepared gold nanoparticles in micro-emulsion and found the optimum ratio of micro-emulsion for preparing gold nanoparticles. We reported a new stabilizer for preparing gold nanoparticles in aqueous and found the optimum mass ratio between the stabilizer and chlorauric acid. All gold nanoparticles prepared by these two methods were characterized by transmission electron microscopy, ultraviolet-visible spectrophotometer and synchronous light-scattering spectrophotometer. The results of transmission electron microscopy showed that the diameter range of gold nanoparticles prepared in micro-emulsion was 5~10 nm, and that in aqueous was 10~15 nm. They all had homogeneous distribution and dense structures.

Characterization of Magnetic Nanoparticles Using Energy-Selected Transmission Electron Microscopy

2002 ◽  
Vol 8 (5) ◽  
pp. 403-411 ◽  
Author(s):  
María J. Sayagués ◽  
Teresa C. Rojas ◽  
Asunción Fernández ◽  
Rafal E. Dunin-Borkowski ◽  
Ron C. Doole ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Magnetic Nanoparticles ◽  
Inert Gas ◽  
Sonochemical Method ◽  
Nano Composite ◽  
Transmission Electron ◽  
Metal Oxide Layer

Fe, Co, and Ni magnetic nanoparticles have been characterized using energy-selected imaging in a high-resolution transmission electron microscope. The samples comprised Fe/FeOx and Co/CoOx nanoparticles synthesized by inert gas evaporation and a Ni/C nano-composite prepared by a sonochemical method. All of the particles examined were found to be between 5 and 30 nm in size, with the Fe and Co crystals coated in 5–10 nm of metal oxide layer and the Ni metallic crystallites embedded in an amorphous carbon spherical matrix.

scholarly journals Silica-coated Magnetic Nanoparticles Activate Microglia and Induce Neurotoxic D-Serine Secretion

2021 ◽  
Author(s):  
Tae Hwan Shin ◽  
Da Yeon Lee ◽  
Balachandran Manavalan ◽  
Shaherin Basith ◽  
Yun-Cheol Na ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amino Acid ◽  
Magnetic Nanoparticles ◽  
Mouse Brain ◽  
Cortical Neurons ◽  
Neuronal Cells ◽  
Primary Microglia ◽  
Transmission Electron ◽  
Amino Acid Profiling

Abstract BackgroundNanoparticles have been studied for brain imaging, diagnosis, and drug delivery owing to their versatile properties due to their small sizes. However, there are growing concerns that nanoparticles may exert toxic effects in the brain. In this study, we assessed direct nanotoxicity on microglia, the resident macrophages of the central nervous system, and indirect toxicity on neuronal cells exerted by silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye [MNPs@SiO2(RITC)]. MethodsWe investigated MNPs@SiO2(RITC)-induced biological changes in BV2 murine microglial cells via RNA-sequencing-based transcriptome analysis and gas chromatography-mass spectrometry-based intracellular and extracellular amino acid profiling. Morphological changes were analyzed by transmission electron microscopy. Indirect effects of MNPs@SiO2(RITC) on neuronal cells were assessed by Transwell-based coculture with MNPs@SiO2(RITC)-treated microglia. MNPs@SiO2(RITC)-induced biological changes in the mouse brain in vivo were examined by immunohistochemical analysis.ResultsBV2 murine microglial cells were morphologically activated and the expression of Iba1, an activation marker protein, was increased after MNPs@SiO2(RITC) treatment. transmission electron microscopy analysis revealed lysosomal accumulation of MNPs@SiO2(RITC) and the formation of vesicle-like structures in MNPs@SiO2(RITC)-treated BV2 cells. The expression of several genes related to metabolism and inflammation were altered in 0.1 µg/µl MNPs@SiO2(RITC)-treated microglia when compared with that in non-treated (control) and 0.01 µg/µl MNPs@SiO2(RITC)-treated microglia. Combined transcriptome and amino acid profiling analyses revealed that the transport of serine family amino acids, including glycine, cysteine, and serine, was enhanced. However, only serine was increased in the growth medium of activated microglia; especially, excitotoxic d-serine secretion from primary rat microglia was the most strongly enhanced. Activated primary microglia reduced intracellular ATP levels and proteasome activity in cocultured neuronal cells, especially in primary cortical neurons, via d-serine secretion. Moreover, ubiquitinated proteins accumulated and inclusion bodies were increased in primary dopaminergic and cortical neurons cocultured with activated primary microglia. In vivo, MNPs@SiO2(RITC), d-serine, and ubiquitin aggresomes were distributed in the MNPs@SiO2(RITC)-treated mouse brain. ConclusionsMNPs@SiO2(RITC)-induced activation of microglia triggers excitotoxicity in neurons via d-serine secretion, highlighting the importance of neurotoxicity mechanisms incurred by nanoparticle-induced microglial activation.

Langmuir Layers of Magnetic Nanoparticles

2005 ◽  
Vol 877 ◽  
Author(s):  
Sara A. Majetich ◽  
Madhur Sachan ◽  
Shihai Kan ◽  
Yuhang Cheng ◽  
Julie Gardener
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Self Assembly ◽  
Magnetic Nanoparticle ◽  
Driving Forces ◽  
Transmission Electron ◽  
Carbon Coated ◽  
Co Nanoparticles

AbstractMethods to form magnetic nanoparticle monolayers using non-aqueous Langmuir layers are reported. Following a discussion of the driving forces in various self-assembly techniques, we describe how aqueous Langmuir layers can be modified for use in conjunction with oxidationsensitive nanoparticles. Monolayers are formed using Fe and–Co nanoparticles, and transferred to carbon-coated transmission electron microscopy grids using the Langmuir-Schaefer method.

Internalization of DMSA-Coated Fe3O4 Magnetic Nanoparticles into Mouse Macrophage Cells

2012 ◽  
Vol 455-456 ◽  
pp. 1221-1227
Author(s):  
Ying Xun Liu ◽  
Zhong Ping Chen ◽  
Jin Ke Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Cell Viability ◽  
Prussian Blue ◽  
Biomedical Applications ◽  
Blue Staining ◽  
Mouse Macrophage ◽  
Cytoplasmic Inclusions ◽  
Transmission Electron

This study observed the internalization of Fe3O4magnetic nanoparticles (MNPs) coated with meso-2, -3-dimercaptosuccinnic acid (DMSA) into mouse macrophage RAW264.7 by using transmission electron microscopy (TEM) and Prussian blue staining. The results showed that the DMSA-coated Fe3O4MNPs could be efficiently internalized into RAW264.7 cells. The internalized DMSA-coated Fe3O4MNPs located in the cytoplasmic inclusions. The internalization of DMSA-coated Fe3O4MNPs did not significantly affect the cell viability at given doses (20, 30, 40, 50 and 100 μg/mL) and incubation times (2, 12, 24, 48 and 72 hours), suggesting DMSA-coated Fe3O4MNPs had better biocompatibility. This study demonstrated that DMSA-coated Fe3O4MNPs may provide a potential nanomaterial for biomedical applications.

Preparation and Characterization of Ag-Deposited Silica-Coated Fe3O4 Magnetic Nanoparticles with Recycling Antibacterial Properties

2014 ◽  
Vol 1061-1062 ◽  
pp. 256-261
Author(s):  
Peng Xu ◽  
Shao Wei ◽  
Jing Yang ◽  
Yi Xi Che ◽  
Xiao Yong Cao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transmission Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Antibacterial Properties ◽  
Magnetic Core ◽  
X Ray ◽  
Bacterial Agent ◽  
Transmission Electron

In this paper, a novel anti-bacterial agent of Ag-deposited silica-coated Fe3O4 magnetic nanoparticles was prepared by a template-activated strategy, which possess a silica coated magnetic core and silver nanoparticles on the outer shell. The as-synthesized nanoparticles have been characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX). The obtained products exhibited dispersibility and high magnetization, which also show a good recycling antibacterial activity, and the antibacterial rates against Escherichia coli was all 100 % for 3 cycles.

scholarly journals Silica-Coated Magnetic Nanoparticles Activate Microglia and Induce Neurotoxic D-Serine Secretion

2021 ◽  
Author(s):  
Tae Hwan Shin ◽  
Da Yeon Lee ◽  
Balachandran Manavalan ◽  
Shaherin Basith ◽  
Yun-Cheol Na ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amino Acid ◽  
Magnetic Nanoparticles ◽  
Cortical Neurons ◽  
Neuronal Cells ◽  
Primary Microglia ◽  
Transmission Electron ◽  
Amino Acid Profiling

Abstract Background Nanoparticles have been studied for brain imaging, diagnosis, and drug delivery owing to their versatile properties due to their small sizes. However, there are growing concerns that nanoparticles may exert toxic effects in the brain. In this study, we assessed direct nanotoxicity on microglia, the resident macrophages of the central nervous system, and indirect toxicity on neuronal cells exerted by silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye [MNPs@SiO2(RITC)]. Methods We investigated MNPs@SiO2(RITC)-induced biological changes in BV2 murine microglial cells via RNA-sequencing-based transcriptome analysis and gas chromatography-mass spectrometry-based intracellular and extracellular amino acid profiling. Morphological changes were analyzed by transmission electron microscopy. Indirect effects of MNPs@SiO2(RITC) on neuronal cells were assessed by Transwell-based coculture with MNPs@SiO2(RITC)-treated microglia. MNPs@SiO2(RITC)-induced biological changes in the mouse brain in vivo were examined by immunohistochemical analysis. Results BV2 murine microglial cells were morphologically activated and the expression of Iba1, an activation marker protein, was increased after MNPs@SiO2(RITC) treatment. transmission electron microscopy analysis revealed lysosomal accumulation of MNPs@SiO2(RITC) and the formation of vesicle-like structures in MNPs@SiO2(RITC)-treated BV2 cells. The expression of several genes related to metabolism and inflammation were altered in 0.1 µg/µl MNPs@SiO2(RITC)-treated microglia when compared with that in non-treated (control) and 0.01 µg/µl MNPs@SiO2(RITC)-treated microglia. Combined transcriptome and amino acid profiling analyses revealed that the transport of serine family amino acids, including glycine, cysteine, and serine, was enhanced. However, only serine was increased in the growth medium of activated microglia; especially, excitotoxic d-serine secretion from primary rat microglia was the most strongly enhanced. Activated primary microglia reduced intracellular ATP levels and proteasome activity in cocultured neuronal cells, especially in primary cortical neurons, via d-serine secretion. Moreover, ubiquitinated proteins accumulated and inclusion bodies were increased in primary dopaminergic and cortical neurons cocultured with activated primary microglia. In vivo, MNPs@SiO2(RITC), d-serine, and ubiquitin aggresomes were distributed in the MNPs@SiO2(RITC)-treated mouse brain. Conclusions MNPs@SiO2(RITC)-induced activation of microglia triggers excitotoxicity in neurons via d-serine secretion, highlighting the importance of neurotoxicity mechanisms incurred by nanoparticle-induced microglial activation.

scholarly journals Design, Optimization Process and Efficient Analysis for Preparation of Copolymer-Coated Superparamagnetic Nanoparticles

2017 ◽  
Vol 7 (3) ◽  
Author(s):  
Mahnaz Mahdavi Shahri
Keyword(s):  
Electron Microscopy ◽  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Saturation Magnetization ◽  
Magnetic Particles ◽  
Superparamagnetic Nanoparticles ◽  
Effluent Treatment ◽  
Degree Of Saturation ◽  
Transmission Electron ◽  
Average Size

Magnetic nanoparticles (MNPs) are very important systems with potential use in drug delivery systems, ferrofluids, and effluent treatment. In many situations, such as in biomedical applications, it is necessary to cover inorganic magnetic particles with an organic material, such as polymers. A superparamagnetic nanocomposite Fe3O4/poly(maleic anhydride-co-acrylic acid) P(MAH-co-AA) with a core/shell structure was successfully synthesized by a dispersion polymerization route. Iron oxide nanoparticles were used as a core, and P(MAH-co-AA) as a shell was covered on the surface of the Fe3O4 magnetic nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the Fe3O4/P(MAH-co-AA) magnetic nanocomposite were highly uniform in size and cubic shape with the average size about 17.06 nm. X-ray diffraction confirmed magnetite cores and also indicated that the binding process did not change the phase of Fe3O4. Vibrational sample magnetometer (VSM) revealed the nanoparticles were superparamagnetic and the saturation magnetization was 83.6 and 46.6 emu g-1 for pure Fe3O4 and composite nanoparticles, respectively. Measurements by VSM also showed that the degree of saturation magnetization increased with increasing iron oxide concentration from 1% to 7 wt % of Fe3O4.

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