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Dumbbell-like Pt(x)Pd(100-x)-Fe(3)O(4) nanoparticles (NPs) were synthesized and studied for electrocatalytic reduction and sensing of H(2)O(2). In 0.1 M phosphate buffered saline (PBS) solution, the 4-10 nm Pt(x)Pd(100-x)-Fe(3)O(4) NPs showed the Pt/Pd composition-dependent catalysis with Pt(48)Pd(52)-Fe(3)O(4) NPs having the best activity. The Pt(48)Pd(52)-Fe(3)O(4) NPs were tested for H(2)O(2) detection, and their H(2)O(2) detection limit reached 5 nM, which was suitable for monitoring H(2)O(2) generated from Raw 264.7 cells. These dumbbell-like PtPd-Fe(3)O(4) NPs are the most sensitive probe ever reported and can be used to achieve real-time quantitative detection of H(2)O(2) in biological environment for biological and biomedical applications.

Magnetic nanoparticles are of immense current interest because of their possible use in biomedical and technological applications. Here we demonstrate that the large magnetic anisotropy of FePt nanoparticles can be significantly modified by surface design. We employ X-ray absorption spectroscopy offering an element-specific approach to magnetocrystalline anisotropy and the orbital magnetism. Experimental results on oxide-free FePt nanoparticles embedded in Al are compared with large-scale density functional theory calculations of the geometric- and spin-resolved electronic structure, which only recently have become possible on world-leading supercomputer architectures. The combination of both approaches yields a more detailed understanding that may open new ways for a microscopic design of magnetic nanoparticles and allows us to present three rules to achieve desired magnetic properties. In addition, concrete suggestions of capping materials for FePt nanoparticles are given for tailoring both magnetocrystalline anisotropy and magnetic moments.

A general one-pot protocol is reported to prepare hollow or porous manganese (Mn) oxide, phosphate, sulfide nanoparticles (NPs) via a controlled ion transfer process.

We and others have recently proposed the synthesis of composite nanoparticles that offer strongly enhanced functionality. Here we have used a flower-shaped Au-Fe(3)O(4) nanoparticle as a template to construct an optical probe containing Cy5.5-GPLGVRG-TDOPA on the iron oxide surface and SH-PEG(5000) on the gold surface that can be specifically activated by matrix metalloproteinases expressed in tumors. Gold nanoparticles have excellent quenching properties, but labile surface chemistry in vivo; on the other hand, iron oxide nanoparticles afford robust surface chemistry, but are suboptimal as energy receptors. By a marriage of the two, we have produced a unified structure with performance that is unachievable with the separate components. Our results are a further demonstration that the architecture of nanoparticles can be modulated to tailor their function as molecular imaging/therapeutic agents.

Mechanical property of dumbbell-like Au-Fe(3)O(4) nanoparticles (NPs) is investigated from a synthetic point of view by overgrowing Au(2) on the Au(1)-Fe(3)O(4) NPs. The competitive growth of Au(2) on the preformed Au(1)-Fe(3)O(4) NPs induced an interesting "tug-of-war" between Au(2) and Fe(3)O(4) in the formed Au(2)-Au(1)-Fe(3)O(4) ternary nanostructure. An interpretation of the observed phenomena is proposed based on a mechanical analysis of the stress and strain distribution across the nanoparticle, which is further verified by control experiments with particle size tuned.

This tutorial review summarizes the recent advances in the chemical synthesis and potential applications of monodisperse magnetic nanoparticles. After a brief introduction to nanomagnetism, the review focuses on recent developments in solution phase syntheses of monodisperse MFe(2)O(4), Co, Fe, CoFe, FePt and SmCo(5) nanoparticles. The review further outlines the surface, structural, and magnetic properties of these nanoparticles for biomedicine and magnetic energy storage applications.

Magnetic nanotags (MNTs) are a promising alternative to fluorescent labels in biomolecular detection assays, because minute quantities of MNTs can be detected with inexpensive giant magnetoresistive (GMR) sensors, such as spin valve (SV) sensors. However, translating this promise into easy to use and multilplexed protein assays, which are highly sought after in molecular diagnostics such as cancer diagnosis and treatment monitoring, has been challenging. Here, we demonstrate multiplex protein detection of potential cancer markers at subpicomolar concentration levels and with a dynamic range of more than four decades. With the addition of nanotag amplification, the analytic sensitivity extends into the low fM concentration range. The multianalyte ability, sensitivity, scalability, and ease of use of the MNT-based protein assay technology make it a strong contender for versatile and portable molecular diagnostics in both research and clinical settings.

Dumbbell-like Au-Fe(3)O(4) nanoparticles are synthesized using decomposition of Fe(CO)(5) on the surface of the Au nanoparticles followed by oxidation in 1-octadecene solvent. The size of the particles is tuned from 2 to 8 nm for Au and 4 nm to 20 nm for Fe(3)O(4). The particles show the characteristic surface plasmon absorption of Au and the magnetic properties of Fe(3)O(4) that are affected by the interactions between Au and Fe(3)O(4). The dumbbell is formed through epitaxial growth of iron oxide on the Au seeds, and the growth can be affected by the polarity of the solvent, as the use of diphenyl ether results in flower-like Au-Fe(3)O(4) nanoparticles.

We present an analytical model for detection of multiple magnetic nanoparticles (NP) as biomolecular labels by spin valve (SV) sensors, aiming to establish the relationship between the SV sensor signal and the number of magnetic labels. The model is based on the assumptions of equivalent average field of magnetic NPs and the coherent magnetization rotation of SVs free layer. Using the model, we have calculated the sensor signals of multiple NPs uniformly or randomly distributed over a SV sensor at various aspect ratios of the NP array. Satisfactory signal linearity at low particle number or high aspect ratio has been found. The model also reveals that the SV sensors could be made insensitive to the random configuration of NPs and only sensitive to the number of NPs. This feature is desired for quantitative bio-detection. To check the validity of the model, we performed experiments on a monolayer of 16-um [Fe.sub.3][O.sub.4] NPs coated on 0.3-[micro]m-wide SV sensors. We found that the measured signals could be well described by the analytical model Index Terms--Biosensor, magnetic nanoparticle, multiple nanoparticle detection, spin valve.

Permanent magnets are a class of critical materials for information storage, energy storage, and other magneto‐electronic applications. Compared with conventional bulk magnets, magnetic nanoparticles (MNPs) show unique size‐dependent magnetic properties, which make it possible to control and optimize their magnetic performance for specific applications. The synthesis of MNPs has been intensively explored in recent years. Among different methods developed thus far, chemical synthesis based on solution‐phase reactions has attracted much attention owing to its potential to achieve the desired size, morphology, structure, and magnetic controls. This Minireview focuses on the recent chemical syntheses of strongly ferromagnetic MNPs (Hc>10 kOe) of rare‐earth metals and FePt intermetallic alloys. It further discusses the potential of enhancing the magnetic performance of MNP composites by assembly of hard and soft MNPs into exchange‐coupled nanocomposites. High‐performance nanocomposites are key to fabricating super‐strong permanent magnets for magnetic, electronic, and energy applications. [ABSTRACT FROM AUTHOR]

Keywords: intermetallic phases; magnetic properties; nanotechnology; phase transitions; rare earth EN intermetallic phases magnetic properties nanotechnology phase transitions rare earth 1 1 1 05/29/20 20200526 NES 200526 B Chemical synthesis based on solution-phase reactions b has attracted much attention in the synthesis of magnetic nanoparticles (MNPs) owing to its potential to achieve the desired size, morphology, structure, and magnetic controls. In their Minireview article on page 6757 ff., B. Shen and S. Sun focus on the recent chemical syntheses of strongly ferromagnetic MNPs ( I H i SB c sb >10 kOe) of rare-earth metals and FePt intermetallic alloys. Intermetallic phases, magnetic properties, nanotechnology, phase transitions, rare earth. [Extracted from the article]

Review: 118 refs. [ABSTRACT FROM AUTHOR]

Review: 92 refs. [ABSTRACT FROM AUTHOR]

Abstract: We present proof-of-concept experiments and modeling towards a high-sensitivity magnetic microarray which “tags” a DNA fragment (or other biological samples) with a high-moment magnetic nanoparticle (NanoTag), which is in turn detected by a high-sensitivity spin valve (SV) or magnetic tunnel junction (MTJ) detector array. The detector can count the number of magnetic tags with a resolution of 1–20 magnetic NanoTags, potentially counting individual biomolecules. [Copyright &y& Elsevier]

Review: 427 refs. [ABSTRACT FROM AUTHOR]