scholarly journals Local and long-range atomic/magnetic structure of non-stoichiometric spinel iron oxide nanocrystallites

IUCrJ ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 33-45
Author(s):  
Henrik L. Andersen ◽  
Benjamin A. Frandsen ◽  
Haraldur P. Gunnlaugsson ◽  
Mads R. V. Jørgensen ◽  
Simon J. L. Billinge ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Structural Characterization ◽  
Magnetic Domain ◽  
Scattering Data ◽  
Oxide Nanoparticles ◽  
Total Scattering ◽  
X Ray ◽  
Neutron Total Scattering

Spinel iron oxide nanoparticles of different mean sizes in the range 10–25 nm have been prepared by surfactant-free up-scalable near- and super-critical hydrothermal synthesis pathways and characterized using a wide range of advanced structural characterization methods to provide a highly detailed structural description. The atomic structure is examined by combined Rietveld analysis of synchrotron powder X-ray diffraction (PXRD) data and time-of-flight neutron powder-diffraction (NPD) data. The local atomic ordering is further analysed by pair distribution function (PDF) analysis of both X-ray and neutron total-scattering data. It is observed that a non-stoichiometric structural model based on a tetragonal γ-Fe2O3 phase with vacancy ordering in the structure (space group P43212) yields the best fit to the PXRD and total-scattering data. Detailed peak-profile analysis reveals a shorter coherence length for the superstructure, which may be attributed to the vacancy-ordered domains being smaller than the size of the crystallites and/or the presence of anti-phase boundaries, faulting or other disorder effects. The intermediate stoichiometry between that of γ-Fe2O3 and Fe3O4 is confirmed by refinement of the Fe/O stoichiometry in the scattering data and quantitative analysis of Mössbauer spectra. The structural characterization is complemented by nano/micro-structural analysis using transmission electron microscopy (TEM), elemental mapping using scanning TEM, energy-dispersive X-ray spectroscopy and the measurement of macroscopic magnetic properties using vibrating sample magnetometry. Notably, no evidence is found of a Fe3O4/γ-Fe2O3 core-shell nanostructure being present, which had previously been suggested for non-stoichiometric spinel iron oxide nanoparticles. Finally, the study is concluded using the magnetic PDF (mPDF) method to model the neutron total-scattering data and determine the local magnetic ordering and magnetic domain sizes in the iron oxide nanoparticles. The mPDF data analysis reveals ferrimagnetic collinear ordering of the spins in the structure and the magnetic domain sizes to be ∼60–70% of the total nanoparticle sizes. The present study is the first in which mPDF analysis has been applied to magnetic nanoparticles, establishing a successful precedent for future studies of magnetic nanoparticles using this technique.

scholarly journals Green Synthesis of Magnetic Nanoparticles by Murraya Koenigii Leaves Extract for Biomedical Application

2021 ◽  
Author(s):  
Sivakami M ◽  
Renuka Devi K ◽  
Renuka R
Keyword(s):  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Green Synthesis ◽  
Iron Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Murraya Koenigii ◽  
Magnetic Iron Oxide Nanoparticles ◽  
X Ray ◽  
Magnetic Iron Oxide ◽  
Resonance Band

Abstract Green synthesis of nanoparticles is the method with eco-friendly, cost-effectiveness, and ease of resource availability approach. Nowadays, magnetic nanoparticles need increased due to its use in magnetic sensing, medical imaging, waste water treatment, and antibiotic drugs. In this report, the ecofriendly green synthesis of magnetic iron oxide nanoparticles were efficiently synthesized by using Murraya koenigii leaves extract. UV-visible spectrum revealed the surface Plasmon resonance band at 240 nm and analyzed the formation of iron oxide nanoparticles. X-ray diffraction pattern determined its high crystalline nature with strong intense peaks. Fourier Transform Infra-Red spectrum illustrated the Fe and O bonding stretching vibration. The particle size distribution graph showed the formed particles are in nanometer range. Transmission Electron Micrographs realized the spherical shaped iron oxide nanoparticles with its size at 10–25 nm. The energy dispersive X-ray spectrum and mapping analysis revealed the purity of prepared nanoparticles with only Fe and O presence. The vibrating sample magnetometer analysis showed the paramagnetic behavior of prepared magnetic iron oxide nanoparticles. The antimicrobial assay revealed potent inhibition of iron oxide nanoparticles on various human pathogens. The antioxidant, anti-inflammatory and anti-diabetic assays revealed the biomedical behavior of iron oxide nanoparticles.

Evaluation of Surface-modified Superparamagnetic Iron Oxide Nanoparticles to Optimize Bacterial Immobilization for Bio-separation with the Least Inhibitory Effect on Microorganism Activity

2020 ◽  
Vol 10 (2) ◽  
pp. 166-174
Author(s):  
Mehdi Khoshneviszadeh ◽  
Sarah Zargarnezhad ◽  
Younes Ghasemi ◽  
Ahmad Gholami
Keyword(s):  
Iron Oxide ◽  
Amino Acid ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Surface Coating ◽  
Superparamagnetic Iron Oxide ◽  
Superparamagnetic Iron Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Surface Charges ◽  
Surface Modified

Background: Magnetic cell immobilization has been introduced as a novel, facile and highly efficient approach for cell separation. A stable attachment between bacterial cell wall with superparamagnetic iron oxide nanoparticles (SPIONs) would enable the microorganisms to be affected by an outer magnetic field. At high concentrations, SPIONs produce reactive oxygen species in cytoplasm, which induce apoptosis or necrosis in microorganisms. Choosing a proper surface coating could cover the defects and increase the efficiency. Methods: In this study, asparagine, APTES, lipo-amino acid and PEG surface modified SPIONs was synthesized by co-precipitation method and characterized by FTIR, TEM, VSM, XRD, DLS techniques. Then, their protective effects against four Gram-positive and Gram-negative bacterial strains including Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were examined through microdilution broth and compared to naked SPION. Results: The evaluation of characterization results showed that functionalization of magnetic nanoparticles could change their MS value, size and surface charges. Also, the microbial analysis revealed that lipo-amino acid coated magnetic nanoparticles has the least adverse effect on microbial strain among tested SPIONs. Conclusion: This study showed lipo-amino acid could be considered as the most protective and even promotive surface coating, which is explained by its optimizing effect on cell penetration and negligible reductive effects on magnetic properties of SPIONs. lipo-amino acid coated magnetic nanoparticles could be used in microbial biotechnology and industrial microbiology.

Effect of aluminum doped iron oxide nanoparticles on magnetic properties of the polyacrylonitrile nanofibers

2017 ◽  
Vol 37 (2) ◽  
pp. 135-141
Author(s):  
Armin Ourang ◽  
Soheil Pilehvar ◽  
Mehrzad Mortezaei ◽  
Roya Damircheli
Keyword(s):  
Magnetic Properties ◽  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Negative Interaction ◽  
Magnetic Nanofibers

Abstract In this work, polyacrylonitrile (PAN) was electrospun with and without magnetic nanoparticles (aluminum doped iron oxide) and was turned into magnetic nanofibers. The results showed that nanofibers diameter decreased from 700 nm to 300 nm by adding nanoparticles. Furthermore, pure PAN nanofibers were indicated to have low magnetic ability due to polar bonds that exist in their acrylonitrile groups. Obviously by adding only 4 wt% of the nanoparticles to PAN nanofibers, magnetic ability soared by more than 10 times, but at a higher percentage, it was shown to change just a little due to negative interaction among nanoparticles. This event relates to antiferromagnetically coupling of nanoparticles due to incomplete dispersion at higher percentage.

Superparamagnetic iron oxide nanoparticles enhance glioma radiosensitivity via inducing cell cycle arrest and apoptosis

2020 ◽  
Author(s):  
Jinning Mao ◽  
Meng Jiang ◽  
Xingliang Dai ◽  
Guodong Liu ◽  
Zhixiang Zhuang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Glioma Cells ◽  
Superparamagnetic Iron Oxide ◽  
Spherical Shape ◽  
Treated Group ◽  
Superparamagnetic Iron Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
X Ray

Abstract Aim: Superparamagnetic iron oxide nanoparticles (SPIONs) is a widely used biomedical material for imaging and targeting drug delivery. We synthesized SPIONs and tested their effects on the radiosensitization of glioma.Methods: Acetylated 3-aminopropyltrimethoxysilane (APTS)-coated iron oxide nanoparticles (Fe3O4 NPs) were synthesized via a one-step hydrothermal approach and the surface was chemically modified with acetic anhydride to generate surface charge-neutralized NPs. NPs were characterized by TEM and ICP-AES. Radiosensitivity of U87MG glioma cells was evaluated by MTT assay. Cell cycle and apoptosis in glioma cells were examined by flow cytometry. Results: APTS-coated Fe3O4 NPs had a spherical or quasi-spherical shape with average size of 10.5±1.1 nm. NPs had excellent biocompatibility and intracellular uptake of NPs reached the peak 24 hours after treatment. U87 cell viability decreased significantly after treatment with both X-ray and NPs compared to X-ray treatment alone. Compared to X-ray treatment alone, the percentage of cells in G2/M phase (31.83%) significantly increased in APTS-coated Fe3O4 NPs plus X-ray treated group (P<0.05). In addition, the percentage of apoptotic cells was significant higher in APTS-coated Fe3O4 NPs plus X-ray treated group than in X-ray treatment alone group (P<0.05). Conclusion: APTS-coated Fe3O4 NPs achieved excellent biocompatibility and increased radiosensitivity for glioma cells.

scholarly journals The atomic structure of a MgCo2O4 nanoparticle for a positive electrode of a Mg rechargeable battery

2019 ◽  
Vol 55 (17) ◽  
pp. 2517-2520 ◽  
Author(s):  
Naoto Kitamura ◽  
Yuhei Tanabe ◽  
Naoya Ishida ◽  
Yasushi Idemoto
Keyword(s):  
Monte Carlo ◽  
Atomic Structure ◽  
Positive Electrode ◽  
Scattering Data ◽  
Rechargeable Battery ◽  
Reverse Monte Carlo ◽  
Spinel Type ◽  
Total Scattering ◽  
X Ray ◽  
Neutron Total Scattering

The atomic structure of a spinel-type MgCo2O4 nanoparticle was investigated by the reverse Monte Carlo modelling using X-ray and neutron total scattering data.

The Effect of Focused Ultrasound on Magnetic Polyelectrolyte Capsules Loaded with Dye When Suspended in Tissue-Mimicking Gel

2019 ◽  
Vol 16 (4) ◽  
pp. 355-363 ◽  
Author(s):  
Carmen Stavarache ◽  
Mircea Vinatoru ◽  
Timothy Mason
Keyword(s):  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Exposure Time ◽  
Ultrasonic Irradiation ◽  
Focused Ultrasound ◽  
Relative Degree ◽  
Oxide Nanoparticles ◽  
Dye Release ◽  
Iron Oxide Magnetic Nanoparticles

Background: Capsules containing a dye were prepared by the LbL method with iron oxide nanoparticles (50 nm) in different layers of the shell. Method: The capsules were dispersed in a gel and subjected to focused ultrasonic irradiation at three different powers and exposure times. Result: It was found that the inclusion of iron oxide magnetic nanoparticles in any of the polyelectrolyte shells (4, 6, 8 and 10) strengthened the capsules with respect to capsules without nanoparticles. Incorporation of nanoparticles in shell 8 provided the most resistance to fragmentation under focused ultrasonic irradiation. The relative degree of capsule stability is dependent on both the power of the ultrasound and the exposure time. Conclusion: The presence of iron oxide nanoparticles not only conferred more resistance to fragmentation but also provided a route to protein labelled dye release through sonoporation that was not present for capsules without nanoparticles.

scholarly journals Micromixer Synthesis Platform for a Tuneable Production of Magnetic Single-Core Iron Oxide Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1845
Author(s):  
Abdulkader Baki ◽  
Norbert Löwa ◽  
Amani Remmo ◽  
Frank Wiekhorst ◽  
Regina Bleul
Keyword(s):  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Magnetic Particle ◽  
Biomedical Application ◽  
Ac Susceptibility ◽  
Chemical Properties ◽  
Oxide Nanoparticles ◽  
Aqueous Synthesis ◽  
Characterization Methods

Micromixer technology is a novel approach to manufacture magnetic single-core iron oxide nanoparticles that offer huge potential for biomedical applications. This platform allows a continuous, scalable, and highly controllable synthesis of magnetic nanoparticles with biocompatible educts via aqueous synthesis route. Since each biomedical application requires specific physical and chemical properties, a comprehensive understanding of the synthesis mechanisms is not only mandatory to control the size and shape of desired nanoparticle systems but, above all, to obtain the envisaged magnetic particle characteristics. The accurate process control of the micromixer technology can be maintained by adjusting two parameters: the synthesis temperature and the residence time. To this end, we performed a systematic variation of these two control parameters synthesizing magnetic nanoparticle systems, which were analyzed afterward by structural (transmission electron microscopy and differential sedimentation centrifugation) and, especially, magnetic characterization methods (magnetic particle spectroscopy and AC susceptibility). Furthermore, we investigated the reproducibility of the microtechnological nanoparticle manufacturing process compared to batch preparation. Our characterization demonstrated the high magnetic quality of single-core iron oxide nanoparticles with core diameters in the range of 20 nm to 40 nm synthesized by micromixer technology. Moreover, we demonstrated the high capability of a newly developed benchtop magnetic particle spectroscopy device that directly monitored the magnetic properties of the magnetic nanoparticles with the highest sensitivity and millisecond temporal resolution during continuous micromixer synthesis.

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