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We report an efficient method for the fabrication of a single electron transistor (SET) using DNA-assisted assembly of nanoparticles. In this method, the DNA molecules function not only as the assembler, but also as the modulator for the electron tunneling behaviors of single electron transistors. A study of the assembly between an Au nanoparticle (∼10 nm) and various lengths of DNA molecules confirms the effectiveness of this method in creating a SET. Most devices exhibited clear single electron effects. [ABSTRACT FROM AUTHOR]

Developing innovative tools that facilitate the understanding of sophisticated biological systems has been one of the Holy Grails in the physical and biological sciences. In this Commentary, we discuss recent advances, opportunities, and challenges in the use of nanomaterials as a precision tool for biology and medicine. [ABSTRACT FROM AUTHOR]

The systematic assembly of nanoscale constituents into highly ordered superlattices is of significant interest because of the potential of their multifunctionalities and the discovery of new collective properties. However, successful observations of such superlattice-associated nanoscale phenomena are still elusive. Here, we present magnetic superlattices of Co and Fe3O4 nanoparticles with multidimensional symmetry of either AB (NaCI) or AB2 (AIB2). The discovery of significant enhancement (≈25 times) of ferrimagnetism is further revealed by forming previously undescribed superlattices of magnetically soft-hard Fe3O4@CoFe2O4 through the confined geometrical effect of thermally driven intrasuperlattice phase transition between the nanoparticulate components. [ABSTRACT FROM AUTHOR]

Investigates the synthesis of 'solid solution' and 'core-shell' types of well-defined cobalt-platinum nanoalloys. Influence of redox transmetalation reactions on the alloy formation; Magnetic and structural properties of the obtained nanoparticles; Analysis on the byproduct reactions obtained from the reaction mixtures.

Examines the photochemical synthesis of copper particles from bis(tert-butylacetoacetato)copper and the in-situ spectroscopic elucidation of the photofragmentation processes. Identification of gas-phase photogenerated intermediates; Generation of free ligand and copper-containing species; Involvement of multiple ligand dissociations in the production of copper metal atoms in the gas phase.

The design and synthesis of architectural nanocrystals have been among the important research topics of nanoscience due to their unique size and shape-dependent phenomena. Therefore, systematic directions for synthetic methods and an understanding of the mechanisms by which the size and shape of the nanocrystals can be controlled are of particular interest. While shape-control studies are actively being pursued on the semiconductor and metal nanocrystals, little work exists for magnetic metal oxide system despite their unique nanomagnetism and important technological applications including magnetic information storage, biological tags, and ferrofluids.

Examines the gas phase photoproduction of diatomic metal nitrides during metal nitride laser chemical vapor deposition. Photofragmentation reactions that lead to deposition under two gas-phase conditions; Deposition of films; Molecular collisions; Photochemistry of the films to intramolecular reactions.

The article discusses research concerning the developments in magnetic diagnostic systems. It highlights the rapid point-of-care (POC) diagnostics for specific cellular and molecular detection that are formed on portable, hand-held instruments and reagent-containing test kits. Also emphasized is the significant of POC for inefficiencies improvement of expensive hospital-based medical care and decrease dependence for routine diagnosis in centralized clinics.

Übergangsmetallchalkogenid(TMC)-Nanoflocken der Zusammensetzung MX2 (mit M=Ti, Zr und Hf; X=S und Se) kristallisieren bevorzugt in der Form gleichseitiger regelmäßiger Sechsecke und weisen ein ausgeprägtes Quanten- Confinement auf. Die hexagonale Form von oktaedrischen (1T) TMC-Nanoflocken ist das Ergebnis der Ladungslokalisierung an den Kanten und Ecken und der daraus resultierenden Coulomb-Abstoßung. Größenunabhängig haben alle Nanoflocken die Zusammensetzung MnX2n-2 und daher ein unoxidiertes Metallzentrum, was Dotierzustände hervorruft. Diese Zustände werden für kleine Nanoflocken relevant und führen zu deren metallischen Charakter, aber für größere Nanoflocken (>6 nm) dominieren die Eigenschaften der 2D-Monolage. An die Kanten der Nanoflocken koordinierte Lewis-Basen haben keinen wesentlichen Einfluss auf die elektronische Struktur dieser Spezies und bestätigen die Nützlichkeit der Kolloidsynthese. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles, which exhibit a variety of unique magnetic phenomena that are drastically different from those of their bulk counterparts, are garnering significant interest since these properties can be advantageous for utilization in a variety of applications ranging from storage media for magnetic memory devices to probes and vectors in the biomedical sciences. In this Account, we discuss the nanoscaling laws of magnetic nanoparticles including metals, metal ferrites, and metal alloys, while focusing on their size, shape, and composition effects. Their fundamental magnetic properties such as blocking temperature ( Tb), spin life time (τ), coercivity ( Hc), and susceptibility (χ) are strongly influenced by the nanoscaling laws, and as a result, these scaling relationships can be leveraged to control magnetism from the ferromagnetic to the superparamagnetic regimes. At the same time, they can be used in order to tune magnetic values including Hc, χ, and remanence ( Mr). For example, life time of magnetic spin is directly related to the magnetic anisotropy energy ( KuV) and also the size and volume of nanoparticles. The blocking temperature ( Tb) changes from room temperature to 10 K as the size of cobalt nanoparticles is reduced from 13 to 2 nm. Similarly, Hcis highly susceptible to the anisotropy of nanoparticles, while saturation magnetization is directly related to the canting effects of the disordered surface magnetic spins and follows a linear relationship upon plotting of ms1/3vs r−1. Therefore, the nanoscaling laws of magnetic nanoparticles are important not only for understanding the behavior of existing materials but also for developing novel nanomaterials with superior properties. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles exhibit unique nanoscale properties and their utilization for various magnetic systems is of significant interest. Especially, heterostructured magnetic nanoparticles are emerging as next-generation materials due to their synergistically enhanced magnetism and potential multifunctionalities. Herein, we overview the recent advances in the development of magnetic nanoparticles with a focus on multicomponent heterostructured nanoparticles including alloys, core–shells, and binary superlattices synthesized via nonhydrolytic methods. Their multifunctionalites and high performance capabilities are demonstrated for applications in high density magnetic storages, chemical catalysis, and biomedical separation and diagnostics. [ABSTRACT FROM AUTHOR]

Focuses on the shape- and dopant-controlled magnetic semiconductor nanocrystals. Application of thermolysis of nonpyrophoric precursors under a monosurfactant system; Importance of reaction parameters and growth regimes for nanocrystal synthesis; Factors responsible for the shape determination of nanocrystals.

Studies the ligand to ligand charge transfer in hydrotris(pyrazolyl)borato ligand with copper(I). Intensity of luminescence; Absence of a weak broad absorption band; Occurrence of a solvatochromatic shift in the absorption band; Nature of the orbitals on the ligands; Relative trends in orbital energies.

The article describes a human pilot trial of a soft, smart contact lens for real-time detection of the cortisol concentration in tears using a smartphone. It discusses several approaches to immunoassay and chromatography for monitoring cortisol concentrations, conventional methods require bulky external equipment, which limits their use as mobile health care systems.

The ability to sense and manipulate the state of biological systems has been extensively advanced during the past decade with the help of recent developments in physical tools. Unlike standard genetic and pharmacological perturbation techniques--knockdown, overexpression, small molecule inhibition--that provide a basic on/off switching capability, these physical tools provide the capacity to control the spatial, temporal, and mechanical properties of the biological targets. Among the various physical cues, magnetism offers distinct advantages over light or electricity. Magnetic fields freely penetrate biological tissues and are already used for clinical applications. As one of the unique features, magnetic fields can be transformed into mechanical stimuli which can serve as a cue in regulating biological processes. However, their biological applications have been limited due to a lack of high-performance magnetism-to-mechanical force transducers with advanced spatiotemporal capabilities. In this Account, we present recent developments in magnetic nanotweezers (MNTs) as a useful tool for interrogating the spatiotemporal control of cells in living tissue. MNTs are composed of force-generating magnetic nanoparticles and field generators. Through proper design and the integration of individual components, MNTs deliver controlled mechanical stimulation to targeted biomolecules at any desired space and time. We first discuss about MNT configuration with different force-stimulation modes. By modulating geometry of the magnetic field generator, MNTs exert pulling, dipole-dipole attraction, and rotational forces to the target specifically and quantitatively. We discuss the key physical parameters determining force magnitude, which include magnetic field strength, magnetic field gradient, magnetic moment of the magnetic particle, as well as distance between the field generator and the particle. MNTs also can be used over a wide range of biological time scales. By simply adjusting the amplitude and phase of the applied current, MNTs based on electromagnets allow for dynamic control of the magnetic field from microseconds to hours. Chemical design and the nanoscale effects of magnetic particles are also essential for optimizing MNT performance. We discuss key strategies to develop magnetic nanoparticles with improved force-generation capabilities with a particular focus on the effects of size, shape, and composition of the nanoparticles. We then introduce various strategies and design considerations for target-specific biomechanical stimulations with MNTs. One-to-one particle-receptor engagement for delivering a defined force to the targeted receptor and the small size of the nanoparticles are important. Finally, we demonstrate the utility of MNTs for manipulating biological functions and activities with various spatial (single molecule/cell to organisms) and temporal resolution (microseconds to days). MNTs have the potential to be utilized in many exciting applications across diverse biological systems spanning from fundamental biology investigations of spatial and mechanical signaling dynamics at the single-cell and systems levels to in vivo therapeutic applications. [ABSTRACT FROM AUTHOR]

Cell-based therapies are attractive for treating various degenerative disorders and cancer but delivering functional cells to the region of interest in vivo remains difficult. The problem is exacerbated in dense biological matrices such as solid tissues because these environments impose significant steric hindrances for cell movement. Here, we show that neural stem cells transfected with zinc-doped ferrite magnetic nanoparticles (ZnMNPs) can be pulled by an external magnet to migrate to the desired location in the brain. These magnetically labeled cells (Mag-Cells) can migrate because ZnMNPs generate sufficiently strong mechanical forces to overcome steric hindrances in the brain tissues. Once at the site of lesion, Mag-Cells show enhanced neuronal differentiation and greater secretion of neurotrophic factors than unlabeled control stem cells. Our study shows that ZnMNPs activate zinc-mediated Wnt signaling to facilitate neuronal differentiation. When implemented in a rodent brain stroke model, Mag-Cells led to significant recovery of locomotor performance in the impaired limbs of the animals. Our findings provide a simple magnetic method for controlling migration of stem cells with high therapeutic functions, offering a valuable tool for other cell-based therapies. [ABSTRACT FROM AUTHOR]

Because of the absence of native dangling bonds on the surface of the layered transition metal dichalcogenides (TMDCs), the surface of colloidal quantum dots (QDs) of TMDCs is exposed directly to the solvent environment. Therefore, the optical and electronic properties of TMDCS QDs are expected to have stronger influence from the solvent than usual surface-passivated QDs due to more direct solvent-QD interaction. Study of such solvent effect has been difficult in colloidal QDs of TMDC due to the large spectroscopic heterogeneity resulting from the heterogeneity of the lateral size or (and) thickness in ensemble. Here, we developed a new synthesis procedure producing the highly uniform colloidal monolayer WS2 QDs exhibiting well-defined photoluminescence (PL) spectrum free from ensemble heterogeneity. Using these newly synthesized monolayer WS2 QDs, we observed the strong influence of the aromatic solvents on the PL energy and intensity of monolayer WS2 QD beyond the simple dielectric screening effect, which is considered to result from the direct electronic interaction between the valence band of the QDs and molecular orbital of the solvent. We also observed the large effect of stacking/separation equilibrium on the PL spectrum dictated by the balance between inter QD and QD-solvent interactions. The new capability to probe the effect of the solvent molecules on the optical properties of colloidal TMDC QDs will be valuable for their applications in various liquid surrounding environments. [ABSTRACT FROM AUTHOR]

The magnetic exchange coupling interaction between hard and soft magnetic phases has been important for tailoring nanoscale magnetism, but spin interactions at the core-shell interface have not been well studied. Here, we systematically investigated a new interface phenomenon termed enhanced spin canting (ESC), which is operative when the shell thickness becomes ultrathin, a few atomic layers, and exhibits a large enhancement of magnetic coercivity (HC). We found that ESC arises not from the typical hard-soft exchange coupling but rather from the large magnetic surface anisotropy (KS) of the ultrathin interface. Due to this large increase in magnetism, ultrathin core-shell nanoparticles overreach the theoretical limit of magnetic energy product ((BH)max) and exhibit one of the largest values of specific loss power (SLP), which testifies to their potential capability as an effective mediator of magnetic energy conversion. [ABSTRACT FROM AUTHOR]

Multidrug resistance (MDR) is a leading cause of failure in current chemotherapy treatment and constitutes a formidable challenge in therapeutics. Here, we demonstrate that a nanoscale magnetic tandem apoptosis trigger (m-TAT), which consists of a magnetic nanoparticle and chemodrug (e.g., doxorubicin), can completely remove MDR cancer cells in both in vitro and in vivo systems. m-TAT simultaneously activates extrinsic and intrinsic apoptosis signals in a synergistic fashion and downregulates the drug efflux pump (e.g., P-glycoprotein) which is one of the main causes of MDR. The tandem apoptosis strategy uses low level of chemodrug (in the nanomolar (nM) range) to eliminate MDR cancer cells. We further demonstrate that apoptosis of MDR cancer cells can be achieved in a spatially selective manner with single-cell level precision. Our study indicates that nanoscale tandem activation of convergent signaling pathways is a new platform concept to overcome MDR with high efficacy and specificity. [ABSTRACT FROM AUTHOR]

Bulk magnetite (Fe3O4), the loadstone used in magnetic compasses, has been known to exhibit magnetoelectric (ME) properties below -10 K; however, corresponding ME effects in Fe3O4 nanoparticles have been enigmatic. We investigate quantitatively the ME coupling of spherical Fe3O4 nanoparticles with uniform diameters (d) from 3 to 15 nm embedded in an insulating host, using a sensitive ME susceptometer. The intrinsic ME susceptibility (MES) of the Fe3O4 nanoparticles is measured, exhibiting a maximum value of -0.6 ps/m at 5 K for d = 15 nm. We found that the MES is reduced with reduced d but remains finite until d = -5 nm, which is close to the critical thickness for observing the Verwey transition. Moreover, with reduced diameter the critical temperature below which the MES becomes conspicuous increased systematically from 9.8 K in the bulk to 19.7 K in the nanoparticles with d = 7 nm, reflecting the core-shell effect on the ME properties. These results point to a new pathway for investigating ME effect in various nanomaterials. [ABSTRACT FROM AUTHOR]

Controlled lateral quantum confinement in single-layer transition-metal chalcogenides (TMCs) can potentially combine the unique properties of two-dimensional (2D) exciton with the size-tunability of exciton energy, creating the single-layer quantum dots (SQDs) of 2D TMC materials. However, exploring such opportunities has been challenging due to the limited ability to produce well-defined SQDs with sufficiently high quality and size control, in conjunction with the commonly observed inconsistency in the optical properties. Here, we report an effective method to synthesize high-quality and size-controlled SQDs of WSe2 via multilayer quantum dots (MQDs) precursors, which enables grasping a clear picture of the role of lateral confinement on the optical properties of the 2D exciton. From the single-particle optical spectra and polarization anisotropy of WSe2 SQDs of varying sizes in addition to their ensemble data, we reveal how the properties of 2D exciton in single-layer TMCs evolve with increasing lateral quantum confinement. [ABSTRACT FROM AUTHOR]

Sound perception via mechano-sensation is a remarkably sensitive and fast transmission process, converting sound as a mechanical input to neural signals in a living organism. Although knowledge of auditory hair cell functions has advanced over the past decades, challenges remain in understanding their biomechanics, partly because of their biophysical complexity and the lack of appropriate probing tools. Most current studies of hair cells have been conducted in a relatively low-frequency range (>1000 Hz); therefore, fast kinetic study of hair cells has been difficult, even though mammalians have sound perception of 20 kHz or higher. Here, we demonstrate that the magnetic force nanoprobe (MFN) has superb spatiotemporal capabilities to mechanically stimulate spatially-targeted individual hair cells with a temporal resolution of up to 9 µs, which is equivalent to approximately 50 kHz; therefore, it is possible to investigate avian hair cell biomechanics at different tonotopic regions of the cochlea covering a full hearing frequency range of 50 to 5000 Hz. We found that the variation of the stimulation frequency and amplitude of hair bundles creates distinct mechanical responsive features along the tonotopic axis, where the kinetics of the hair bundle recovery motion exhibits unique frequency-dependent characteristics: basal, middle, and apical hair bundles can effectively respond at their respective ranges of frequency. We revealed that such recovery kinetics possesses two different time constants that are closely related to the passive and active motilities of hair cells. The use of MFN is critical for the kinetics study of free-standing hair cells in a spatiotemporally distinct tonotopic organization. [ABSTRACT FROM AUTHOR]

The article examines the efficacy of iron oxide-based nanoparticles for magnetoresponsive therapy and multimodal imaging. Information about the nanoscale physicochemical properties and the potential wide range of applications of magnetic nanoparticles, is provided. Also mentioned is the application of magnetic nanoparticles in the ferrofluid of U.S. government agency National Aeronautics and Space Administration (NASA).

A solution-phase synthetic protocol to form two-dimensional (2D) single-layer transition-metal chalcogenides (TMCs) has long been sought; however, such efforts have been plagued with the spontaneous formation of multilayer sheets. In this study, we discovered a solution-phase synthetic protocol, called ‘‘diluted chalcogen continuous influx (DCCI)”, where controlling the chalcogen source influx (e.g., H2S) during its reaction with the transition-metal halide precursor is the critical parameter for the formation of single-layer sheets as examined for the cases of group IV TMCs. The continuous influx of dilute H2S throughout the entire growth period is necessary for large sheet formation through the exclusive a- and b-axial growth processes. By contrast, the burst influx of highly concentrated H2S in the early stages of the growth process forms multilayer TMC nanodiscs. Our DCCI protocol is a new synthetic concept for single-layer TMCs and, in principle, can be operative for wide range of TMC nanosheets. [ABSTRACT FROM AUTHOR]

Texaphyrins are pentaaza expanded porphyrins with the ability to form stable complexes with a variety of metal cations, particularly those of the lanthanide series. In biological milieus, texaphyrins act as redox mediators and mediate the production of reactive oxygen species (ROS). In this review, newer studies involving texaphyrin complexes targeting several different applications in anticancer therapy are described. In particular, the preparation of bismuth and lead texaphyrin complexes as potential α-core emitters for radiotherapy is detailed, as are gadolinium texaphyrin functionalized magnetic nanoparticles with features that make them of interest as dual-mode magnetic resonance imaging contrast agents and as constructs with anticancer activity mediated through ROS-induced sensitization and concurrent hyperthermia. Also discussed are gadolinium texaphyrin complexes as possible carrier systems for the targeted delivery of platinum payloads. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered nanostructures are emerging fast due to their exceptional materials properties. While the importance of physical approaches (e.g., guest intercalation and exfoliation) of 2D layered nanomaterials has been recognized, an understanding of basic chemical reactions of these materials, especially in nanoscale regime, is obscure. Here, we show how chemical stimuli can influence the fate of reaction pathways of 2D layered nanocrystals. Depending on the chemical characteristics (Lewis acid (1O2) or base (H2O)) of external stimuli, TiS2 nanocrystal is respectively transformed to either a TiO2 nanodisc through a "compositional metathesis" or a TiO2 toroid through multistage "edge-selective structural transformation" processes. These chemical reactions can serve as the new design concept for functional 2D layered nanostructures. For example, TiS2(disc)-TiO2(shell) nanocrystal constitutes a high performance type II heterojunction which not only a wide range solar energy coverage (∼80%) with near-infrared absorption edge, but also possesses enhanced electron transfer property. [ABSTRACT FROM AUTHOR]

While interesting and unprecedented material characteristics of two dimensionality (2-D) layered nanomaterials are emerging, their reliable synthetic methodologies are not well developed. In this study we demonstrate general applicability of synthetic protocols to a wide range of colloidal 2-D layered transition-metal chalcogenide (TMC) nanocrystals. As distinctly different from other nanocrystals, we discovered that 2-D layered TMC nanocrystals are unstable in the presence of reactive radicals from elemental chalcogen during the crystal formation. We first introduce the synthesis of titanium sulfide and selenide where well-defined single crystallinity and lateral size controllability are verified, and then such synthetic protocols are extended to all of group IV and V transition-metal sulfide (TiS2, ZrS2, HfS2, VS2, NbS2, and TaS2) and selenide (TiSe2, ZrSe3, HfSe3, VSe2, NbSe2, and TaSe2) nanocrystals. The use of appropriate chalcogen source is found to be critical for the successful synthesis of 2-D layered TMC nanocrystals. CS2 is an efficient chalcogen precursor for metal sulfide nanocrystals, whereas elemental Se is appropriate for metal selenide nanocrystals. We briefly discuss the effects of reactive radical characteristics of elemental S and Se on the formation of 2-D layered TMC nanocrystals. [ABSTRACT FROM AUTHOR]

Early detection and treatment of disease is the most important component of a favorable prognosis. Biomedical researchers have thus invested tremendous effort in improving imaging techniques and treatment methods. Over the past decade, concepts and tools derived from nanotechnology have been applied to overcome the problems of conventional techniques for advanced diagnosis and therapy. In particular, advances in nanoparticle technology have created new paradigms for theranostics, which is defined as the combination of therapeutic and diagnostic agents within a single platform. In this Account, we examine the potential advantages and opportunities afforded by magnetic nanoparticles as platform materials for theranostics. [ABSTRACT FROM AUTHOR]

We present a colloidal route for the synthesis of ultrathin ZrS2 (UT-ZrS2) nanodiscs that are ∼1.6 nm thick and consist of approximately two unit cells of S-Zr-S. The lateral size of the discs can be tuned to 20, 35, or 60 nm while their thickness is kept constant. Under the appropriate conditions, these individual discs can self- assemble into face-to-face-stacked structures containing multiple discs. Because the S-Zr-S layers within individual discs are held together by weak van der Waals interactions, each UT-ZrS2 disc provides spaces that can serve as host sites for intercalation. `When we tested UT-ZrS2 discs as anodic materials for Li+ intercalation, they showed excellent nanoscale size effects, enhancing the discharge capacity by 230% and greatly improving the stability in comparison with bulk ZrS2. The nanoscale size effect was especially prom!- nent for their performance in fast charging/discharging cycles, where an 88% average recovery of reversible capacity was observed for UT-ZrS2 discs with a lateral diameter of 20 nm. The nanoscale thickness and lateral size of UT-ZrS2 discs are critical for fast and reliable intercalation cycling because those dimensions both increase the surface area and provide open edges that enhance the diffusion kinetics for guest molecules. [ABSTRACT FROM AUTHOR]

Recently a memristor (Chua, L. O. IEEE Trans. Circuit Theory1971, 18, 507), the fourth fundamental passive circuit element, has been demonstrated as thin film device operations (Strukov, D. B.; Snider, G. S.; Stewart, D. R.; Williams, R. S. Nature (London)2008, 453, 80; Yang, J. J.; Pickett. M. D.; Li, X.; Ohlberg, D. A. A.; Stewart, D. R.; Williams, R. S. Nat. Nanotechnol.2008, 3, 429). A new addition to the memristor family can be nanoparticle assemblies consisting of an infinite number of monodispersed, crystalline magnetite (Fe3O4) particles. Assembly of nanoparticles that have sizes below 10 nm, exhibits at room temperature a voltage−current hysteresis with an abrupt and large bipolar resistance switching (ROFF/RON≈ 20). Interestingly, observed behavior could be interpreted by adopting an extended memristor model that combines both a time-dependent resistance and a time-dependent capacitance. We also observed that such behavior is not restricted to magnetites; it is a general property of nanoparticle assemblies as it was consistently observed in different types of spinel structured nanoparticles with different sizes and compositions. Further investigation into this new nanoassembly system will be of importance to the realization of the next generation nanodevices with potential advantages of simpler and inexpensive device fabrications. [ABSTRACT FROM AUTHOR]

We demonstrate a novel magnetophoretic immunoassay of allergen-specific immunoglobulin E (IgE) based on the magnetophoretic deflection velocity of a microbead that is proportional to the associated magnetic nanoparticles under enhanced magnetic field gradient in a microchannel. In this detection scheme, two types of house dust mites, Dermatophagoides farinae (D. farinae) and Dermatophagoides pteronyssinus (D. pteronyssinus), were used as the model allergens. Polystyrene microbeads were conjugated with each of the mite extracts followed by incubation with serum samples. The resulting mixture was then reacted with magnetic nanoparticle-conjugated anti-human IgE for detection of allergen-specific IgE by using sandwich immuno-reactions. A ferromagnetic microstructure combined with a permanent magnet was employed to increase the magnetic field gradient (∼104 T/m) in a microfluidic device. The magnetophoretic velocities of microbeads were measured in a microchannel under applied magnetic field, and the averaged velocity was well correlated with the concentration of allergen-specific IgE in serum. From the analysis of pooled sera obtained from 44 patients, the detection limits of the allergen-specific human IgEs for D. farinae and D. pteronyssinus were determined to be 565 (0.045 IU/mL) and 268 fM (0.021 IU/mL), respectively. These values are 1 order of magnitude lower than those by a conventional CAP system. For evaluation of reproducibility and accuracy, unknown sera were subjected to a blind test by using the developed assay system, and they were compared with the CAP system. As a result, coefficient of variance was less than 10%, and the developed method enabled a fast assay with a tiny amount of serum (∼10 μL). [ABSTRACT FROM AUTHOR]

Although multicomponent core-shell type nanomaterials are one of the highly desired structural motifs due to their simultaneous multifunctionalities, the fabrication strategy for such nanostructures is still in a primitive stage. Here, we present a redox-transmetalation process that is effective as a general protocol for the fabrication of high quality and well-defined core-shell type bimetallic nanoparticles on the sub-10 nm scale. Various core-shell type nanomaterials including Co@Au, Co@Pd, Co@Pt, and Co@Cu nanoparticles are fabricated via transmetalation reactions. Compared to conventional sequential reduction strategies, this transmetalation process has several advantages for the fabrication of core-shell type nanoparticles: (i) no additional reducing agent is needed and (ii) spontaneous shell layer deposition occurs on top of the core nanoparticle surface and thus prevents self-nucleation of secondarily added metals. We also demonstrate the versatility of these core-shell structures by transferring Co@Au nanoparticles from an organic phase to an aqueous phase via a surface modification process. The nanostructures, magnetic properties, and reaction byproducts of these core-shell nanoparticles are spectroscopically characterized and identified, in part, to confirm the chemical process that promotes the core-shell structure formation. [ABSTRACT FROM AUTHOR]

The structure, magnetism, and phase transition of core-shell type CoPt nanoparticles en route to solid solution alloy nanostructures are systematically investigated. The characterization of COcorePtshell nanoparticles obtained by a "redox transmetalation" process by transmission electron microscopy (TEM) and, in particular, X-ray absorption spectroscopy (XAS) provides clear evidence for the existence of a core-shell type bimetallic interlacial structure. Nanoscale phase transitions of the COcorePtshell structures toward c-axis compressed face-centered tetragonal (fct) solid solution alloy CoPt nanoparticles are monitored at various stages of a thermally induced annealing process and the obtained fct nanoalloys show a large enhancement of their magnetic properties with ferromagnetism. The relationship between the nanostructures and their magnetic properties is in part elucidated through the use of XAS as a critical analytical tool. [ABSTRACT FROM AUTHOR]

Achieving high accuracy in the imaging of biological targets is a challenging issue. For MRI, to enhance imaging accuracy, two different imaging modes with specific contrast agents are used; one is a T1 type for a "positive" MRI signal and the other is a T2 type for a "negative" signal. Conventional contrast agents respond only in a single imaging mode and frequently encounter ambiguities in the MR images. Here, we propose a "magnetically decoupled" core-shell design concept to develop a dual mode nanoparticle contrast agent (DMCA). This DMCA not only possesses superior MR contrast effects but also has the unique capability of displaying "AND" logic signals in both the T1 and T2 modes. The latter enables self-confirmation of images and leads to greater diagnostic accuracy. A variety of novel DMCAs are possible, and the use of DMCAs can potentially bring the accuracy of MR imaging of diseases to a higher level. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles are useful nanomaterials that have demonstrated the ability to contain and release cargos with mediation by gatekeepers. Magnetic nanocrystals have the ability to exhibit hyperthermic effects when placed in an oscillating magnetic field. In a system combining these two materials and a thermally sensitive gatekeeper, a unique drug delivery system can be produced. A novel material that incorporates zinc-doped iron oxide nanocrystals within a mesoporous silica framework that has been surface-modified with pseudorotaxanes is described. Upon application of an AC magnetic field, the nanocrystals generate local internal heating, causing the molecular machines to disassemble and allowing the cargos (drugs) to be released. When breast cancer cells (MDA-MB-231) were treated with doxorubicin-loaded particles and exposed to an AC field, cell death occurred. This material promises to be a noninvasive, externally controlled drug delivery system with cancer-killing properties. [ABSTRACT FROM AUTHOR]

Co@Pt–Au nanoparticles, which have enhanced magnetism and high stability in aqueous media, are utilized in conjunction with MRI to monitor the structural evolution of Aβ assemblies, especially Aβ protofibrils in the early reversible stages. [ABSTRACT FROM AUTHOR]

A magnetic field is successfully utilized to induce the fabrication of size controllable one-dimensional (1-D) supercrystals which are composed of a highly crystalline assembly of fcc-packed cobalt nanoparticles; the anisotropy associated supercrystal magnetism is enhanced with four times higher coercivity than that of randomly aggregated nanoparticles. [ABSTRACT FROM AUTHOR]

The article presents the development of heterodimer nanoparticles of FePt-Au with multifunctionalities. After the examining the magnetic and optical properties of heterodimer nanoparticles, FePt-Au heterodimers exhibit supermagnetic behavior with a magnetization value of 52 emu/g at 5 T, which is consistent with the initial FePt seed nanoparticles. The author further investigated the applicability of FePt-Au heterodimer nanoparticles for in vitor molecular MR imaging of biological targets.

This article presents information about a study related to the surface modulation of magnetic nanocrystals in the development of highly efficient magnetic resonance (MR) probes for intracellular labeling. It describes the preparation of these probes and the results from studies exploring their transport into various cell types and MR contrast effect, cytotoxicity, and application in in vivo monitoring of neural stem cell migration in rat spinal cord. The combination of the cell-labeling strategy developed in this study and the development of highly sensitive nanocrystal MR probes will enable long-term MR monitoring of cell-based medical treatments and cancer metastasis.

The article discusses nanoscale size effect of magnetic nanocrystals and their utilization for cancer diagnosis via magnetic resonance imaging. The ability to synthetically tune the materials properties in terms of size, shape, and composition of inorganic nanocrystals makes them exhibit enhanced optical, magnetic and electronic properties when compared to their bulk counterparts. Such novel properties provide the potential for huge improvements in biomedical sciences including detection, diagnosis, and therapeutic systems. Among theses nanocrystals, superparamagnetic nanocrystals are now emerging in biomedical applications with new possibilities. In particular, magnetic nanocrystals have a capability as an excellent magnetic resonance signal enhancer that can resolve the weakness of current magnetic resonance imaging techniques.

Examines the surfactant driven shape-controlled synthesis of gallium phosphide semiconductor nanocrystals. Thermal decomposition of molecular precursor; Crystal shape; Crystal growth.

Investigates the mechanism of single-crystalline star-shaped nanocrystals. Structures of lead sulphide nanocrystals; Binding ligand of dodecylamine to the sulphides crystals; Growth process of monomers.