Magnetic Tunability via Control of Crystallinity and Size in Polycrystalline Iron Oxide Nanoparticles.

Iron oxide nanoparticles (IONPs) are widely used for biomedical applications due to their unique magnetic properties and biocompatibility. However, the controlled synthesis of IONPs with tunable particle sizes and crystallite/grain sizes to achieve desired magnetic functionalities across single-domain and multi-domain size ranges remains an important challenge. Here, a facile synthetic method is used to produce iron oxide nanospheres (IONSs) with controllable size and crystallinity for magnetic tunability.

Seroprevalence of hepatitis E virus (HEV) among male craft and manual workers in Qatar (2020-2021).

Background: The rapid growth of Qatar in the last two decades has attracted a large influx of immigrant craft and manual workers (CMWs) seeking employment in jobs associated with food handling, domestic service, and construction. Nearly 60 % of Qatar's population are expatriates CMWs, including many from hyperendemic countries for HEV. Thus, estimating the seroprevalence of HEV in Qatar and understanding its epidemiology is essential for public health efforts to control HEV transmission in Qatar.

A review of rapid food safety testing: using lateral flow assay platform to detect foodborne pathogens.

The detrimental impact of foodborne pathogens on human health makes food safety a major concern at all levels of production. Conventional methods to detect foodborne pathogens, such as live culture, high-performance liquid chromatography, and molecular techniques, are relatively tedious, time-consuming, laborious, and expensive, which hinders their use for on-site applications. Recurrent outbreaks of foodborne illness have heightened the demand for rapid and simple technologies for detection of foodborne pathogens.

Piezoelectricity across 2D Phase Boundaries.

Piezoelectricity in low-dimensional materials and metal-semiconductor junctions has attracted recent attention. Herein, a 2D in-plane metal-semiconductor junction made of multilayer 2H and 1T' phases of molybdenum(IV) telluride (MoTe ) is investigated. Strong piezoelectric response is observed using piezoresponse force microscopy at the 2H-1T' junction, despite that the multilayers of each individual phase are weakly piezoelectric.

2D Electrets of Ultrathin MoO with Apparent Piezoelectricity.

Since graphene, a variety of 2D materials have been fabricated in a quest for a tantalizing combination of properties and desired physiochemical behavior. 2D materials that are piezoelectric, i.e.

Recombinant expression, characterization, and quantification in human cancer cell lines of the Anaplastic Large-Cell Lymphoma-characteristic NPM-ALK fusion protein.

Systemic anaplastic large cell lymphoma (ALCL) is an aggressive T-cell lymphoma most commonly seen in children and young adults. The majority of pediatric ALCLs are associated with the t(2;5)(p23;q35) translocation which fuses the Anaplastic Lymphoma Kinase (ALK) gene with the Nucleophosmin (NPM) gene. The NPM-ALK fusion protein is a constitutively-active tyrosine kinase, and plays a major role in tumor pathogenesis.

PCB-Based Magnetometer as a Platform for Quantification of Lateral-Flow Assays.

This work presents a proof-of-concept demonstration of a novel inductive transducer, the femtoMag, that can be integrated with a lateral-flow assay (LFA) to provide detection and quantification of molecular biomarkers. The femtoMag transducer is manufactured using a low-cost printed circuit board (PCB) technology and can be controlled by relatively inexpensive electronics. It allows rapid high-precision quantification of the number (or amount) of superparamagnetic nanoparticle reporters along the length of an LFA test strip.

Correction: Enhancement of lateral flow assay performance by electromagnetic relocation of reporter particles.

[This corrects the article DOI: 10.1371/journal.pone.

Specific Detection of Proteins Using Exceptionally Responsive Magnetic Particles.

Sensitivity and specificity are among the most important parameters for viable sensor technologies based on magnetic nanoparticles. In this work, we describe synthetic routes and analytical approaches to improve both aspects. Magnetic iron oxide particles having diameters of 120, 440, and 700 nm were synthesized, and their surfaces were specifically functionalized.

Enhancement of lateral flow assay performance by electromagnetic relocation of reporter particles.

Lateral flow assays (LFAs) are a widely-used point-of care diagnostic format, but suffer from limited analytical sensitivity, especially when read by eye. It has recently been reported that LFA performance can be improved by using magnetic reporter particles and an external magnetic field applied at the test line. The mechanism of sensitivity/performance enhancement was suggested to be concentration/retardation of reporter particles at the test line.

Magnetic Sensing Potential of FeO Nanocubes Exceeds That of FeO Nanospheres.

This paper highlights the relation between the shape of iron oxide (FeO) particles and their magnetic sensing ability. We synthesized FeO nanocubes and nanospheres having tunable sizes via solvothermal and thermal decomposition synthesis reactions, respectively, to obtain samples in which the volumes and body diagonals/diameters were equivalent. Vibrating sample magnetometry (VSM) data showed that the saturation magnetization () and coercivity of 100-225 nm cubic magnetic nanoparticles (MNPs) were, respectively, 1.

Near-infrared-responsive, superparamagnetic Au@Co nanochains.

This manuscript describes a new type of nanomaterial, namely superparamagnetic Au@Co nanochains with optical extinctions in the near infrared (NIR). The Au@Co nanochains were synthesized via a one-pot galvanic replacement route involving a redox-transmetalation process in aqueous medium, where Au salt was reduced to form Au shells on Co seed templates, affording hollow Au@Co nanochains. The Au shells serve not only as a protective coating for the Co nanochain cores, but also to give rise to the optical properties of these unique nanostructures.

Ultrasensitive Magnetic Nanoparticle Detector for Biosensor Applications.

Ta/Ru/Co/Ru/Co/Cu/Co/NiFe/Ta spin-valve giant magnetoresistive (GMR) multilayers were deposited using UHV magnetron sputtering and optimized to achieve a 13% GMR ratio before patterning. The GMR multilayer was patterned into 12 sensor arrays using a combination of e-beam and optical lithographies. Arrays were constructed with 400 nm × 400 nm and 400 nm × 200 nm sensors for the detection of reporter nanoparticles.

Enzymatic conversion of magnetic nanoparticles to a non-magnetic precipitate: a new approach to magnetic sensing.

Magnetic sensing utilizes the detection of biomolecule-conjugated magnetic nanoparticles (MNPs). Our new strategy offers a novel approach to magnetic sensing where in situ conversion produces a "loss of signal" in the sensing device. This report demonstrates the enzymatic conversion of Fe3O4 MNPs to a non-magnetic precipitate via reduction by l-ascorbic acid generated by the action of alkaline phosphatase.

Enzymatic synthesis of magnetic nanoparticles.

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.

Patterning of magnetic thin films and multilayers using nanostructured tantalum gettering templates.

This work demonstrates that a nonmagnetic thin film of cobalt oxide (CoO) sandwiched between Ta seed and capping layers can be effectively reduced to a magnetic cobalt thin film by annealing at 200 °C, whereas CoO does not exhibit ferromagnetic properties at room temperature and is stable at up to ∼400 °C. The CoO reduction is attributed to the thermodynamically driven gettering of oxygen by tantalum, similar to the exothermic reduction-oxidation reaction observed in thermite systems. Similarly, annealing at 200 °C of a nonmagnetic [CoO/Pd]N multilayer thin film sandwiched between Ta seed and Ta capping layers results in the conversion into a magnetic [Co/Pd]N multilayer, a material with perpendicular magnetic anisotropy that is of interest for magnetic data storage applications.

Fabrication of dense non-circular nanomagnetic device arrays using self-limiting low-energy glow-discharge processing.

We describe a low-energy glow-discharge process using reactive ion etching system that enables non-circular device patterns, such as squares or hexagons, to be formed from a precursor array of uniform circular openings in polymethyl methacrylate, PMMA, defined by electron beam lithography. This technique is of a particular interest for bit-patterned magnetic recording medium fabrication, where close packed square magnetic bits may improve its recording performance. The process and results of generating close packed square patterns by self-limiting low-energy glow-discharge are investigated.

Tuning the magnetic properties of nanoparticles.

The tremendous interest in magnetic nanoparticles (MNPs) is reflected in published research that ranges from novel methods of synthesis of unique nanoparticle shapes and composite structures to a large number of MNP characterization techniques, and finally to their use in many biomedical and nanotechnology-based applications. The knowledge gained from this vast body of research can be made more useful if we organize the associated results to correlate key magnetic properties with the parameters that influence them. Tuning these properties of MNPs will allow us to tailor nanoparticles for specific applications, thus increasing their effectiveness.

Development of Pinhole-Free Amorphous Aluminum Oxide Protective Layers for Biomedical Device Applications.

This paper describes synthesis of ultrathin pinhole-free insulating aluminum oxide layers for electronic device protection in corrosive liquid environments, such as phosphate buffered saline (PBS) or clinical fluids, to enable emerging biomedical applications such as biomolecular sensors. A pinhole-free 25-nm thick amorphous aluminum oxide layer has been achieved using ultra-high vacuum DC magnetron reactive sputtering of aluminum in oxygen/argon plasma followed by oxygen plasma post-processing. Deposition parameters were optimized to achieve the best corrosion protection of lithographically defined device structures.

Cubic Silica-Coated and Amine-Functionalized FeCo Nanoparticles with High Saturation Magnetization.

By systematically varying the reaction parameters in a liquid-phase reduction reaction, large FeCo nanocubes with tunable body diagonal lengths of 175, 350, and 450 nm were synthesized. The nanocubes were initially stabilized with poly(vinyl pyrrolidone) (PVP) and then coated with a relatively thin layer of silica (~55 nm thick), which allowed them to retain their cubic shape. The magnetization curves showed that the PVP-stabilized nanocubes exhibited a high saturation magnetization of 167 ± 4 emu/g.

Carbon nanotube based 3-D matrix for enabling three-dimensional nano-magneto-electronics [corrected].

This letter describes the use of vertically aligned carbon nanotubes (CNT)-based arrays with estimated 2-nm thick cobalt (Co) nanoparticles deposited inside individual tubes to unravel the possibility of using the unique templates for ultra-high-density low-energy 3-D nano-magneto-electronic devices. The presence of oriented 2-nm thick Co layers within individual nanotubes in the CNT-based 3-D matrix is confirmed through VSM measurements as well as an energy-dispersive X-ray spectroscopy (EDS).

Multilevel-3D bit patterned magnetic media with 8 signal levels per nanocolumn.

This letter presents an experimental study that shows that a 3(rd) physical dimension may be used to further increase information packing density in magnetic storage devices. We demonstrate the feasibility of at least quadrupling the magnetic states of magnetic-based data storage devices by recording and reading information from nanopillars with three magnetically-decoupled layers. Magneto-optical Kerr effect microscopy and magnetic force microscopy analysis show that both continuous (thin film) and patterned triple-stack magnetic media can generate eight magnetically-stable states.

Light-induced covalent immobilization of monolayers of magnetic nanoparticles on hydrogen-terminated silicon.

Specifically tailored ω-alkenyl-1-carboxylic acids were synthesized for use as surfactants in the single-step preparation of manganese ferrite (MnFe2O4) nanoparticles (NPs). Monodisperse manganese ferrite NPs terminated with ω-alkenyl moieties were prepared via a one-pot reaction at high temperature without the need of ligand exchange. Using this approach, simple adjustment of the rate of heating allowed precise tuning of the size of the nanoparticles, which were characterized in bulk form by transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD).

Micromagnetic study of domain wall dynamics in bit-patterned nanodots.

Domain wall dynamics in magnetic nanodots is critical to the understanding of the magnetization reversal mechanisms in bit-patterned arrays, the issues of writeablility, data rate maximization, and bit stability. In this work, micromagnetic simulations were carried out to investigate the dynamics of domain walls in disk-shaped nanostructures with large built-in perpendicular anisotropy. Due to the strong demagnetizing effect, the domain wall motion falls into the supercritical regime.