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Effect of Recombinant Plasmid pEGFP-AFP-hTNF on Liver Cancer Cells (HepG2 Cells) in vitro when Delivered by PEG-PEI/Fe3O4 Nanomagnetic Fluid Original Research Article
Journal of the Formosan Medical Association, Volume 110, Issue 5, May 2011, Pages 326-335
Baoxiong Zhuang, Yangde Zhang, Jian Peng, Haowei Zhang, Tiehui Hu, Jie Zeng, Yifan Li
Simultaneous determination of nine flavonoids in Polygonum hydropiper L. samples using nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction combined with ultrahigh performance liquid chromatography–mass spectrometry Original Research Article
Journal of Pharmaceutical and Biomedical Analysis, Volume 54, Issue 2, 25 January 2011, Pages 311-316
Xian Yang, Bo-Chu Wang, Xue Zhang, Shui-Ping Yang, Wei Li, Qian Tang, Gurinder K. Singh
A simple, inexpensive, and efficient nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction (HF-LPME) technique combined with ultrahigh performance liquid chromatography–mass spectrometry (UPLC–MS) was developed for the simultaneous analysis of nine flavonoids in Polygonum hydropiper L. samples. The final, optimised extraction conditions were as follows: an organic solvent of ethyl acetate, a donor phase of aqueous KH2PO4 at pH 3.0, an acceptor phase of aqueous NaHCO3 at pH 8.5, a stirring rate of 1000 rpm, and an extraction time of 50 min. Under these conditions, analyte calibration curves were all linear, with correlation coefficients ≥0.9994. The relative standard deviation for all analytes in intra-day (0.8–2.2%) and inter-day (1.7–3.5%) precision tests was well within the acceptable ranges, as were the limits of quantitation (LOQ < 0.054 μg/L) and detection (LOD < 0.170 μg/L). Recoveries for all standard compounds were between 95.17% and 99.82%, with a RSD of no more than 2.3%. Correlative analyses demonstrated that the physicochemical parameters of the compounds themselves also influenced the extraction efficiency. This technology proved to be rapid, sensitive, and reliable for the quality control of P. hydropiper L. samples.
Keywords: Polygonum hydropiper L.; Nanomagnetic powder; Three-phase HF-LPME; UPLC–MS
UV laser photodeposition of nanomagnetic soot from gaseous benzene and acetonitrile–benzene mixture Original Research Article
Journal of Photochemistry and Photobiology A: Chemistry, Volume 220, Issues 2-3, 20 May 2011, Pages 188-194
Josef Pola, Akihiko Ouchi, M. Maryško, V. Vorlíček, Jan Šubrt, S. Bakardjieva, Zdeněk Bastl
Megawatt KrF laser gas-phase photolysis of benzene and acetonitrile–benzene mixture was studied by using mass spectroscopy–gas-chromatography and Fourier transform infrared spectroscopy for analyses of volatile products, and by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, electron microscopy and magnetization measurements for analyses of solid products deposited from the gas-phase. The results are consistent with carbonization of benzene and decomposition of non-absorbing acetonitrile in carbonizing benzene through collisions with excited benzene and/or its fragments. The solid products from benzene and acetonitrile–benzene mixture have large surface area and are characterized as nanomagnetic amorphous carbonaceous soot containing unsaturated C centers prone to oxidation. The nanosoot from acetonitrile–benzene mixture incorporates CN groups, confirms reactions of benzene fragments with CN radical and has a potential for modification by reactions at the CN bonds.
Keywords: Benzene; Acetonitrile; Laser photodeposition; Nanomagnetic soot; CN-substituted soot
Adsorption, desorption, and conformational changes of lysozyme from thermosensitive nanomagnetic particles Original Research Article
Journal of Colloid and Interface Science, Volume 320, Issue 1, 1 April 2008, Pages 15-21
N. Shamim, H. Liang, K. Hidajat, M.S. Uddin
Adsorption of globular protein, lysozyme, on thermosensitive poly(N-isopropylacrylamide) coated nanomagnetic particles was studied at different temperatures and pHs. It was observed that a maximum amount of lysozyme was adsorbed at a temperature above the lower critical solution temperature (LCST) (32 °C ) of the polymer and at the isoelectric point (pI=11) of lysozyme. Desorption was carried out using either NaH2PO4 (pH 4) or NaSCN (pH 6) as the desorbing agents. Conformational changes in lysozyme on desorption from nanomagnetic particles was studied by circular dichroism and intrinsic fluorescence spectroscopy. Lysozyme desorbed by NaH2PO4 showed very little conformational changes while lysozyme desorbed by NaSCN showed significant conformational changes, and 87% enzymatic activity was retained in the desorbed enzyme for desorption by NaH2PO4.
Keywords: N-isopropylacrylamide; Lower critical solution temperature (LCST); Isoelectric point; Lysozyme; Conformational changes
Thermosensitive polymer (N-isopropylacrylamide) coated nanomagnetic particles: Preparation and characterization Original Research Article
Colloids and Surfaces B: Biointerfaces, Volume 55, Issue 1, 15 March 2007, Pages 51-58
N. Shamim, L. Hong, K. Hidajat, M.S. Uddin
Thermosensitive polymer coated nanomagnetic adsorbents were synthesized by seed polymerization using surface modified nanomagnetic particles as the seeds. The Fe3O4 nanomagnetic particles were prepared by chemical precipitation of Fe2+ and Fe3+ salts in the ratio of 1:2 under alkaline and inert condition. The surface of these particles was modified by surfactants to achieve stability against agglomeration. These stable particles were then polymerized using N-isopropylacrylamide (NIPAM) as the main monomer, methylene-bis-acrylamide as the crosslinker and potassium per sulfate as the initiator. The thermosensitive adsorbents were characterized by using transmission electron micrography (TEM) and vibrating sample magnetometer (VSM). TEM showed that the particle remained discrete with a mean diameter of 12 nm. Magnetic measurements revealed that the particles are superparamagnetic only with a decrease of magnetism after binding with the polymer due to the increase in surface spin disorientation. Pure Fe3O4 spinel structure of these nanoparticles was indicated by the X-ray diffraction (XRD) patterns. The polymerization of NIPAM with the surface modified nanomagnetic particles was confirmed by Fourier transform spectroscopy (FTIR), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). In addition, the adsorption/desorption of BSA molecule on these thermosensitive nanoparticles was investigated as a function of temperature. More than 60% desorption efficiency was achieved under appropriate condition.
Keywords: Surfactant; Thermosensitive magnetic nanoparticles; N-Isopropylacrylamide; Superparamagnetism
On-chip Extraordinary Hall-effect sensors for characterization of nanomagnetic logic devices Original Research Article
Solid-State Electronics, Volume 54, Issue 9, September 2010, Pages 1027-1032
M. Becherer, J. Kiermaier, S. Breitkreutz, G. Csaba, X. Ju, J. Rezgani, T. Kießling, C. Yilmaz, P. Osswald, P. Lugli, D. Schmitt-Landsiedel
Ferromagnetic Co/Pt films and single-domain magnets are characterized by various types of Extraordinary Hall-Effect (EHE) sensors. The magnetron sputtered multilayer films are annealed and measured in the temperature range of 22 °C T 75 °C. By focused ion beam (FIB) irradiation, the magnetic properties of the Co/Pt stack are tailored to define both the switching field and the geometry of nanomagnetic single domain dots. A submicron sized EHE-sensor for read-out of field-coupled computing devices is presented. The applied sensing structure is suitable to electrically probe the output states of field-coupled magnetic logic gates. Furthermore, it reveals details on the magnetic properties of submicron-scale single-domain dots and the main measured features are confirmed by micromagnetic simulations. A ‘split-current’ architecture is chosen, where Hall sensing takes place in a single lateral direction, in order to keep field-coupling to adjacent nanomagnets undisturbed. From angular measurements we conclude that the reversal mechanism of the FIB patterned magnetic dots is domain-wall driven. The sensor is a main component needed for integration of nanomagnetic computing units embedded into microelectronic systems.
Keywords: Extraordinary Hall-Effect; Co/Pt multilayer; Magnetic QCA; Field-coupled logic; Ferromagnetic computing
Vibration sample magnetometry, a good tool for the study of nanomagnetic inclusions Original Research Article
Superlattices and Microstructures, Volume 43, Issues 5-6, May-June 2008, Pages 482-486
S. Diaz-Castanon, J.C. Faloh-Gandarilla, E. Munoz-Sandoval, M. Terrones
The accurate determination of the ferromagnetic contribution in a composite in which the ratio of the ferromagnetic part vs. the total of composite is 10−4–10−5 is a problem of great importance in relation to the development of new materials in our days. In this work, the potential of Vibration Sample Magnetometry (VSM) in the identification and quantification of nanomagnetic inclusions is illustrated and discussed in three different cases: PbFe12O19/ Al2O3 thin films, nanopowders of magnetite in a polymeric matrix, and carbon nanotubes with iron inside in a silica matrix (Fe/ CNx/ SiO2). In all cases, the determination of the existence of preferential orientation, the correct quantification of the magnetic part, and the dependence of the coercive field with on synthesis conditions were revealed using this technique.
Keywords: Magnetic characterization; Nanostructures
Adaptation and performance of the Cartesian coordinates fast multipole method for nanomagnetic simulations Original Research Article
Journal of Magnetism and Magnetic Materials, Volume 321, Issue 22, November 2009, Pages 3687-3692
Wen Zhang, Stephan Haas
An implementation of the fast multiple method (FMM) is performed for magnetic systems with long-ranged dipolar interactions. Expansion in spherical harmonics of the original FMM is replaced by expansion of polynomials in Cartesian coordinates, which is considerably simpler. Under open boundary conditions, an expression for multipole moments of point dipoles in a cell is derived. These make the program appropriate for nanomagnetic simulations, including magnetic nanoparticles and ferrofluids. The performance is optimized in terms of cell size and parameter set (expansion order and opening angle) and the trade off between computing time and accuracy is quantitatively studied. A rule of thumb is proposed to decide the appropriate average number of dipoles in the smallest cells, and an optimal choice of parameter set is suggested. Finally, the superiority of Cartesian coordinate FMM is demonstrated by comparison to spherical harmonics FMM and FFT.
Keywords: FMM; Cartesian; Magnet
Thermosensitive polymer coated nanomagnetic particles for separation of bio-molecules Original Research Article
Separation and Purification Technology, Volume 53, Issue 2, 25 February 2007, Pages 164-170
N. Shamim, L. Hong, K. Hidajat, M.S. Uddin
Core–shell type thermosensitive magnetic particles were prepared via seed polymerization process. Double layer surfactant coated magnetic particles were first synthesized and then a rich poly-(N-isopropylacrylamide) (PNIPAM) shell layer was attached using double layer magnetic particles as the seeds. Thiodiglycolic acid was used as the primary surfactant and 4-vinylaniline as the secondary surfactant. Carboxylated thermosensitive microspheres were prepared by adding methacrylic acid (MAA) in the polymerization process. PNIPAM has a lower critical solution temperature (LCST) of 32 °C in water, and changes from hydrophilic below the LCST to hydrophobic above it. The size of these thermosensitive polymer coated magnetic particles was measured by using transmission electron microscopy (TEM). TEM results show that magnetic particles were nanosized and the calculated mean diameter of the particles was about 12 nm. Bovine serum albumin (BSA) was selected as a model protein for the separation study. Adsorption of BSA on the thermosensitive magnetic particles was mainly dependent on the properties of the particles’ surface. By increasing the temperature above the LCST of PNIPAM, the particles shrank and were able to adsorb larger quantity of proteins, which was subsequently desorbed at lower temperature. It was believed that carboxylated thermosensitive particles adsorb proteins through hydrogen bonding. When the two extremes of hydrophobic interaction and hydrogen bonding were compared, it was found that more proteins are adsorbed using the later interaction.
Keywords: Double layer magnetic particles; Thermosensitive magnetic particles; Poly-(N-isopropylacrylamide); Lower critical solution temperature (LCST); Methacrylic acid (MAA); Bovine serum albumin (BSA); Adsorption
Extracting anisotropy energy barrier distributions of nanomagnetic systems from magnetization/susceptibility measurements
Journal of Magnetism and Magnetic Materials, Volume 321, Issue 9, May 2009, Pages L21-L27
Rongkun Zheng, Hongwei Gu, Bei Zhang, Hui Liu, Xixiang Zhang, Simon P. Ringer
Anisotropy barrier distributions of single domain particle systems are an important issue in the nanomagnetism and its applications. Different methods to extract the distribution from temperature, field, or time-dependent magnetization/susceptibility are reviewed and compared. A single domain particle system is measured to test the methods.
Keywords: Magnetic nanoparticles; Nanomagnetism; Anisotropy barrier distribution; Single domain particles
United States Patent 7,126,797
Hasegawa , et al. October 24, 2006
Spin valve magnetoresistive element having pinned magnetic layer composed of epitaxial laminated film having magnetic sublayers and nanomagnetic interlayer
A magnetic sensor includes a pinned magnetic layer having first and second magnetic sublayers sandwiching a nonmagnetic metal layer. The nonmagnetic metal layer contains at least one of Ru, Re, Os, Ti, Rh, Ir, Pd, Pt, and Al. The atoms in the first magnetic sublayer and the atoms in the nonmagnetic metal layer overlap with each other, while each of the crystal structures is deformed. The deformations in the crystal structure of the first magnetic sublayer increase the magnetostriction constant, thereby increasing the magnetoelastic effect of the magnetic sensor.
United States Patent 6,906,256
Wang June 14, 2005
Nanomagnetic shielding assembly
An assembly that contains a substrate, nanomagnetic material, and a device for cooling the substrate. The nanomagnetic material has a mass density of at least about 0.01 grams per cubic centimeter, a saturation magnetization of from about 1 to about 36,000 Gauss, a coercive force of from about 0.01 to about 5,000 Oersteds, a relative magnetic permeability of from about 1 to about 500,000, and an average particle size of less than about 100 nanometers.
United States Patent 6,828,786
Scherer , et al. December 7, 2004
Method and apparatus for nanomagnetic manipulation and sensing
The invention combines (A) capabilities in fabrication, characterization, and manipulation of single domain magnetic nanostructures, with (B) the use of binding chemistry of biological molecules to modify the magnetic nanostructures into magnetic sensors and magnetically controllable nanoprobes. A biological characterization scheme is realized by combining nanomanipulation and observation of small magnetic structures in fluids. By coating nanomagnets with biological molecules, ultra-small, highly sensitive and robust biomagnetic devices are defined, and molecular electronics and spin electronics are combined. When these nano-sensors are integrated into microfluidic channels, highly efficient single-molecule detection chips for rapid diagnosis and analysis of biological agents are constructed.
United States Patent 6,815,609
Wang , et al. November 9, 2004
A magnetically shielded substrate assembly includes a substrate and, disposed over the substrate, a magnetic shield with a magnetic shielding factor of at least about 0.5. The magnetic shield has a film of nanomagnetic material containing at least about 40 weight percent of nomagnetic material with a mass density of at least about 0.01 grams per cubic centimeter, a saturization magnetization of from about 1 to about 36,000 Gauss, a coercive force of from about 0.01 to about 5,000 Oersteds, a relative magnetic permeability of from about 1 to about 500,000, and an average particle size of less than about 100 nanometers. This film of nanomagnetic material has a squareness of from about 0.5 to about 1.0.