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The YBa2Cu3O7-δ (YBCO) ultrathin films were prepared by off-axis rf magnetron sputtering on SrTiO3 (STO) substrate with a 300-Å-thick La2/3Ca1/3MnO3 (LCMO) buffer layer. At low temperature, the magnetism of the LCMO buffer layer seemed to be screened by the epitaxial YBCO layer with a thickness of more than about 125 Å. A remarkable magnetoresistance (MR) ratio was obtained for thinner YBCO cap layer. The superconducting transition temperature, Tc, decreases with decreasing YBCO thickness and disappears at the thickness of less than 85 Å. X-ray diffraction (XRD) was used to characterize the quality of the buffer and epitaxial films. The out-of-plane lattice parameters for both buffer and epitaxial layer varied monotonically. The surface structures of the buffer and the epitaxial YBCO films were characterized by atomic force microscopy (AFM). Interfacial diffusions for cations such as Y, Cu, La, Ca and Sr were deduced from Auger electron spectroscopy (AES). The larger diffusion length was found at the interface between YBCO and LCMO, which may relate to the suppression of superconductivity and magnetoresistance.

We report a simple strategy to construct a multiple gadolinium complex decorated fullerene (CGDn) as an enhanced T1 contrast agent. The CGDn exhibits much higher T1 relaxivity (∼49.7 mM(-1) s(-1)) than individual Gd-DOTA, and shows excellent T1 contrast enhancement ability both in vitro and in vivo.

Magnetic resonance angiography using gadolinium-based molecular contrast agents suffers from short diagnostic window, relatively low resolution and risk of toxicity. Taking into account the chemical exchange between metal centers and surrounding protons, magnetic nanoparticles with suitable surface and interfacial features may serve as alternative T1 contrast agents. Herein, we report the engineering on surface structure of iron oxide nanoplates to boost T1 contrast ability through synergistic effects between exposed metal-rich Fe3O4(100) facets and embedded Gd2O3 clusters. The nanoplates show prominent T1 contrast in a wide range of magnetic fields with an ultrahigh r1 value up to 61.5 mM(-1) s(-1). Moreover, engineering on nanobio interface through zwitterionic molecules adjusts the in vivo behaviors of nanoplates for highly efficient magnetic resonance angiography with steady-state acquisition window, superhigh resolution in vascular details, and low toxicity. This study provides a powerful tool for sophisticated design of MRI contrast agents for diverse use in bioimaging applications.

Multifunctional nanostructures with both diagnostic and therapeutic capabilities have attracted considerable attention in biomedical research because they can offer great advantages in disease management and prognosis. In this work, a facile way to transfer the hydrophobic iron oxide (IO) nanoparticles into aqueous media by employing carboxylic graphene oxide (GO-COOH) as the transferring agent has been reported. In this one-step process, IO nanoparticles adhere to GO-COOH and form water-dispersible clusters via hydrophobic interactions between the hydrophobic ligands of IO nanoparticles and the basal plane of GO-COOH. The multiple IO nanoparticles on GO-COOH sheets (IO/GO-COOH) present a significant increase in T2 contrast enhancement. Moreover, the IO/GO-COOH nanoclusters also display a high photothermal conversion efficiency and can effectively inhibit tumor growth through the photothermal effects. It is envisioned that such IO/GO-COOH nanocomposites combining efficient MRI and photothermal therapy hold great promise in theranostic applications.

Postoperative recurrence and metastasis are the major problems for the current treatment of hepatocellular carcinomas (HCC) in the clinic, including hepatectomy and liver transplantation. Here, we report that arsentic-loaded nanoparticles (ALNPs) are able to reduce the invasion of HCC cells in vitro, and, more importantly, can strongly suppress the invasion and metastasis of HCC in vivo without adverse side effects. Compared to free drug arsenic trioxide , ALNPs can deliver the drug into cancer cells more efficiently, destroy the structure of microtubules and reduce the aggregation of microfilaments in cell membranes more significantly. Furthermore, our results also reveal that tumor cells in murine blood were reduced remarkably after intravenous injection of ALNPs, indicating that this nano-drug may efficiently kill circulating tumor cells in vivo. In conclusion, our nano-drug ALNPs have great potential for the suppression of metastasis of HCC, which may open up a new avenue for the effective treatment of HCC without metastasis and recurrence.

Investigating the surface structure, including crystal surface and surface-coating ligands, of nanoparticulate T1 contrast agent may help to understand the T1 relaxation enhancement in vitro and in vivo. This study presents a novel strategy to develop high-performance T1 magnetic resonance imaging (MRI) contrast agents through optimizing the nanocrystal surface and the nanobio interface. Based on the optimized crystal surface, the novel manganese oxide nanocubes (MOCs) show significantly higher surface-to-volume ratio and an approximately threefold higher r1 value compared to traditional manganese oxide nanospheres. Concurrently, transferring MOCs into aqueous media by dopamine derivatization can avoid the oxidation of Mn(II) ions and provide abundant magnetic core. This optimized surface endows MOCs with a high chemical exchange efficiency during T1 relaxation. Of particular significance, a rationally designed pH-induced charge-switchable surfaces can be negatively charged and corona-free in blood and positively charged surface in tumor sites. This unique feature improves the circulation behavior of this intelligent T1 contrast agent in blood and increases cancer cell uptake to achieve accurate detection of solid tumor, holding great potential in aiding early and precise tumor diagnosis. This study provides a novel tool for sophisticated design of high-performance T1 MRI contrast agents in bioimaging applications.

Tyrosinase is an important marker of human diseases such as the neurodegeneration associated with Parkinson's disease and melanoma. Sensitive detection of tyrosinase activity in vitro and inside cells is of great significance to medical diagnostics and skin disorder treatments. With unique photophysical properties, semiconductor quantum dots (QDs) are employed as photoluminescent platforms for various biosensing, in particular for the detection of enzyme activities. In this work, QDs are functionalized with tyrosine and zwitterionic molecules to construct a nanometer-scale scaffold (QD-Tyr conjugate), and this is used to test tyrosinase activity in vitro and inside cells. Tyrosinase oxidizes tyrosine to dopachrome and switches on the electron-transfer access, which relates to fluorescence quenching. High quenching efficiency is achieved by shortening the distance between the electron donors and acceptors, which is attributed to the small size of the conjugated tyrosine. Enzymatic process curves reveal the enhanced enzymatic activity on the conjugated nanoparticle substrate, which leads to highly sensitive detection of tyrosinase (as low as 1 nM). It is also demonstrated that QD-Tyr conjugates can sensitively probe intracellular tyrosinase in melanoma cells, which promises great potential in disease monitoring and medical diagnostics.

MnO-embedded iron oxide nanoparticles (MnIO-NPs) can be treated as potential dual-modal contrast agents. However, their overall bio-effects and potential toxicity remain unknown. In this study, the metabolic effects of MnIO-NPs (dosed at 1 and 5 mg Fe/kg) on Sprague–Dawley rats were investigated using metabonomic analysis, histopathological examination, and conventional biochemical analysis. The histological changes included a focal inflammation in the liver at high-dose and a slightly enlarged area of splenic white pulp after 48 h post-dose. Blood biochemical analysis showed that albumin, globulins, aspartate aminotransferase, lactate dehydrogenase, blood urea nitrogen, and glucose changed distinctly compared to the control. The metabonomic analysis of body fluids (serum and urine) and tissues (liver, kidney, and spleen) indicated that MnIO-NPs induced metabolic perturbation in rats including energy, nucleotides, amino acids and phospholipid metabolisms. Besides, the variations of supportive nutrients: valine, leucine, isoleucine, nicotinamide adenine dinucleotide (phosphate), and nicotinamide, and the conjugation substrates: glycine, taurine, glutamine, glutathione, and methyl donors (formate, sarcosine, dimethylglycine, choline, and betaine) were involved in detoxification reaction of MnIO-NPs. The obtained information would provide identifiable ground for the candidate selection and optimization.

Multifunctional nanocomposites have the potential to integrate sensing, diagnostic, and therapeutic functions into a single nanostructure. Herein, we synthesize Fe3O4@polydopamine core-shell nanocomposites (Fe3O4@PDA NCs) through an in situ self-polymerization method. Dopamine, a melanin-like mimic of mussel adhesive proteins, can self-polymerize to form surface-adherent polydopamine (PDA) films onto a wide range of materials including Fe3O4 nanoparticles used here. In such nanocomposites, PDA provides a number of advantages, such as near-infrared absorption, high fluorescence quenching efficiency, and a surface for further functionalization with biomolecules. We demonstrate the ability of the Fe3O4@PDA NCs to act as theranostic agents for intracellular mRNA detection and multimodal imaging-guided photothermal therapy. This work would stimulate interest in the use of PDA as a useful material to construct multifunctional nanocomposites for biomedical applications.

Epitaxial thin films of YBa2Cu3Oy (YBCO) have been prepared on yttrium-stabilized zirconia substrates with and without a buffer layer. The early growth, crystallinity and surface morphology of these thin films have been characterized by X-ray diffraction, rocking curves, scanning electron microscope, in situ conductance measurements, and surface step profiler. The full width at half maximum of the ( 0 0 5 ) peak of rocking curve was found to be less than 0.1°. Over a wide scanning range of 2000 μm the average surface roughness is just 5 nm, indicating very smooth films. Grazing incident X-ray reflection and positron annihilation spectroscopy shows well-defined interfaces between layers and substrate. By applying a new Eu2CuO4 (ECO) buffer layer the initial formation of YBCO appears to grow layer-by-layer rather than the typical island growth mode. The obtained results reveal significant improvements at the early formation and crystallinity of YBCO by using the 214-T ′ ECO as a buffer layer.

The variation of structure for the nominal composition of YBa 1.8 La 0.2 Cu 3 O y (YBLCO) at the temperature range of 78 K K was studied. YBLCO shows a superconducting transition temperature of T c ∼ 87 K (zero resistance temperature). There is no phase transition detected in the accuracy of our experiments in the entire temperature range. The temperature dependency of lattice parameters and thermal expansion behavior for the sample was determined by the XRD method in the temperature range of 78–288 K. These data exhibit anomalies with T

The variation of structure and transport properties for the nominal composition of Y0.8Ca0.2Ba1.8La0.2Cu3Oy (YCBLC) at temperature range of 78 K K were studied. YCBLC shows a superconducting transition temperature of Tc∼83 K. There is no phase transition detected in the accuracy of our experiments in the whole temperature range. The dependences of lattice constants upon temperature can be discussed in three temperature regions. The other atomic parameters, or deduced structural parameters, such as the orthorhombic strain, the lattice strain, some selected bond lengths and bond angles all depend on temperature. They all can be divided into three temperature regions. The dependences of the atomic structural parameters on temperature indicate that these atomic structural parameters may play a role on the superconductivity to some extent.

We have introduced a new buffer material, neodymium copper oxide Nd2CuO4, to improve the initial epitaxy of YBa2Cu3Oy ultrathin films on yttrium stabilized ZrO2 (YSZ). This material has a stable tetragonal structure with lattice constants very similar to that of YBa2Cu3Oy. It behaves like an oxide semiconductor and is highly resistive. Unlike most buffer materials with the 123 structure, the structure and electric properties of the Nd2CuO4 film are not sensitive to the oxygen deficiency and it will not cause any degradation in superconductivity of the grown YBa2Cu3Oy films. We found that even with a very thin layer of Nd2CuO4 the interaction between YBa2Cu3Oy and YSZ could be efficiently blocked. Measurements by using XRD, rocking curve, and cross-sectional transmission electron microscopy (TEM) indicate that the crystallinity and initial epitaxy of YBa2Cu3Oy films can be significantly improved by such a Nd2CuO4 buffer layer. Good superconducting transitions and high critical current density have been obtained with the film thickness down to 10 nm. It has been also found that the Nd2CuO4 thin films always present a very smooth surface.

Epitaxial thin films of YBa 2 Cu 3 O 7 (YBCO) have been deposited on Y–ZrO 2 (YSZ) substrates by means of the pulse laser deposition technique. It has been found that the initial epitaxy of YBCO thin films grown on YSZ can be significantly improved by using La 1.85 Sr 0.15 CuO 4 (LSCO) as a buffer layer. X-ray diffraction measurements show that the epitaxial YBCO films have single in-plane orientation with YBCO [100]∥LSCO [100] and LSCO [100]∥YSZ [110]. The real-time resistance measurements reveal that with LSCO buffer layers the initial formation of the YBCO ultra-thin films changes from the island growth to the layer-by-layer growth.

The nominal composition of Y 0.8 Ca 0.2 Ba 2− x La x Cu 3 O y (YBLCO) cuprates with x ≤0.50 has been synthesized by the standard solid state reaction technique. X-ray diffraction and the resistivity measurements are used to characterize the structure and the superconductivity of YBLCO cuprates. There is no structural phase transition in the whole doping range. The dependencies of the lattice constants and some other structural parameters on the content of La for the samples YBLCO with x ≤0.20 are different than those for the samples with x ≥0.25. The zero resistance temperature T c0 increases with the increase of the content of La in YBLCO as x ≤0.20, and decreases as x ≥0.25. We compared these results with those of Nd-doped Y 0.8 Ca 0.2 Ba 2− z Nd z Cu 3 O y cuprates. It seems that T c0 is related to the structural parameters due to Ca and La codoping in YBLCO.

Y 1− x Ca x Ba 1.8 Nd 0.2 Cu 3 O y (YCBNC) compounds with x ≤0.50 are synthesized using the solid state reaction technique. The structure for all samples is characterized by X-ray diffraction with Rietveld refinements. The structural parameters change with the content of Ca in YCBNC. The orthorhombic strain decreases with the increase of Ca content. The transport properties for YCBNC are measured by the standard four-probe method in the temperature range from 20 to 300 K. The superconducting transition temperature decreases with the increase of Ca content in YCBNC. The resistivity dependence of temperature, and the relation of the structural parameters vs. the content of Ca show that a competition mechanism may exist in YCBNC due to Ca replacing for Y together with Nd substituting for Ba in YCBNC.

Nd doped Y 0.8 Ca 0.2 Ba 2− x Nd x Cu 3 O y YBNCO compounds with x ≤0.50 have been prepared by the solid state reaction technique. The structure and the superconductivity for YBNCO compounds are characterized. The zero resistance transition temperature T c0 for each sample was measured. T c0 increases with the increase of the content of Nd in YBNCO as x ≤0.15, and decreases as x ≥0.20. X-ray diffraction studies show that there is no structural phase transition in the whole doping range. The dependencies of the lattice constants and some other structural parameters on the content of Nd for the samples YBNCO with x ≤0.20 have different behaviour than that for the samples with x ≥0.25. It seems that the superconductivity of YBNCO is related to the structural changes due to Ca and Nd co-doping.

Influence of electric currents with a high density on the transport behavior of La 0.9 Hf 0.1 MnO 3 thin films has been investigated in the absence of magnetic field. With different dc-currents from I = 0.5 mA (current density J = 1.0 × 10 3 A/cm 2 ) to 25.0 mA ( J = 4.8 × 10 4 A/cm 2 ) applied on the sample, a striking observation is the significant decrease of the metal-insulator transition peak. The observed reduction ratio, the electroresistance ER = [ R (0) − R (I)]/ R (I) is ∼20%. This observation is similar to what we observed in other CMR systems like La 1− x Ca x MnO 3 and La 1− x Ba x MnO 3 , indicating that the current-induced ER is a common feature for the CMR materials. The introduced new state is metastable and can be well repeated. Experiments revealed that it is not caused by oxygen deficiency. Although the nature behind such an effect has not been well understood yet, the observed ER effect seems to favor a percolative phase separation picture.

We investigated the influence of static electric field on the transport properties in La0.7Ce0.3MnO3 epitaxial thin films by using a simple field effect configuration (FEC), which was formed on a single layer film. Substrates act as gates and films as channels. Such an easily manipulative technique avoids many possible problems appeared in multilayer structures, such as poor interface and severe inter-diffusion, which may influence the intrinsic characteristics of investigated targets. One knows that tetravalence-doped La0.7Ce0.3MnO3 (LEMO) systems exhibit metal-insulator transition and ferromagnetic behavior, similar to the ditravalence-doped La0.7Ca0.3 MnO3. However, for the conductive mechanism of LEMO, strong controversies have existed for a long time with whether it is intrinsically electron-type or hole-type. Our experiments give evidence of the hole-type nature in LEMO. In the device with LEMO as channel and LaAlO3(LAO) as gate, applied positive bias poles gate and induces charge at the area between gate and channel. The polarized charge in the gate is compensated by inducing electrons in the channel. If LEMO is of electron-type, the increased carrier density would cause a decease of channel resistance. However, we experimentally found the channel resistance remarkably increases upon a positive bias. Such a fact is completely the same as the behavior observed in hole-doped La 0.7Ca0.3MnO3channel, and thus strongly supports the hole-type nature in LEMO channel. Furthermore, we found that the large field effect in LEMO is nonlinear and polarity dependent on the applied bias. A percolative phase separation picture is taking into account to interpret the observed field effect

Ramp junctions have been successfully synthesized utilizing an Y 1- x Pr x Ba 2 Cu 3 O y barrier with a continually graded concentration of Pr . The properties of these junctions are dominated by the barrier material rather than the boundary. Also, the damaged ramp surface is excluded from the weak link region so its influence is minimized. The Josephson coupling occurs at the naturally formed S/N interfaces within the Y 1- x Pr x Ba 2 Cu 3 O y layer. Thus it leads to a highly transparent S/N boundary and greatly enhances the performance of the junctions. The effective thickness of the barrier can be varied even post fabrication, depending on the measuring temperature and the concentration gradient. The temperature dependence of the barrier thickness and Josephson properties were investigated and compared with those junctions with a conventional single barrier. These unique features should motivate further studies on the nature of these junctions.

Recently, some types of MnO nanoparticle (Mn-NP) with favorable imaging capacity have been developed to improve the biocompatible profile of the existing Mn-based MRI contrast agent Mn-DPDP; however, the overall bio-effects and potential toxicity remain largely unknown. In this study, (1)H NMR-based metabolic profiling, integrated with traditional biochemical analysis and histopathological examinations, was used to investigate the absorption, distribution, metabolism, excretion and toxicity of Mn-NPs as candidates for MRI contrast agent. The metabolic responses in biofluids (plasma and urine) and tissues (liver, spleen, kidney, lung and brain) from rats could be divided into four classes following Mn-NP administration: Mn biodistribution-dependent, time-dependent, dose-dependent and complicated metabolic variations. The variations of these metabolites involved in lipid, energy, amino acid and other nutrient metabolism, which disclosed the metabolic fate and biological effects of Mn-NPs in rats. The changes of metabolic profile implied that the disturbance and impairment of biological functions induced by Mn-NP exposure were correlated with the particle size and the surface chemistry of nanoparticles. Integration of metabonomic technology with traditional methods provides a promising tool to understand the toxicological behavior of biomedical nanomaterials and will result in informed decision-making during drug development.

Disclosed are nanoparticles comprising octapod iron oxide having eight trigonal bipyramidal arms and a method of preparing the same. The nanoparticles are prepared by heating a mixture of a ferric carboxylate, a carboxylic acid, a chloride salt, water, and a non-polar solvent, to a temperature above about 300° C. Also disclosed is a method of magnetic resonance imaging a tissue in a mammal, comprising use of the aforesaid nanoparticles.

Glutathione (GSH) capped CdTe semiconductor quantum dots (QDs) are applied for detecting mercuric ions (Hg(2+)) of trace quantity. The synthesis of GSH-capped CdTe (CdTe@GSH) QDs is cost-efficient and straightforward. We observed that Hg(2+) can quantitatively quench the fluorescence of CdTe@GSH QDs and further induce the slight redshift of emission peaks due to the quantum confinement effect. Detailed studies by spectroscopy, dynamic light scattering (DLS), and electrospray ionization mass spectrometry (ESI-MS) demonstrated that the competitive Hg(2+) binding with GSH makes the surface of CdTe QDs exposed, results in gradual aggregation, and quantitatively changes the photophysical properties of QDs. The whole procedure for detecting Hg(2+) by this protocol took less than 10 min. The experimental limit of detection (LOD) of Hg(2+) can be as low as 5 nM using CdTe@GSH with a low concentration (0.5 nM) because of the excellent fluorescent properties of QDs. This strategy may become a promising means to simply detect Hg(2+) in water with high sensitivity.

We report the design and synthesis of small-sized zwitterion-coated gadolinium-embedded iron oxide (GdIO) nanoparticles, which exhibit a strong T1 contrast effect for tumor imaging through enhanced permeation and retention effect and the ability to clear out of the body in living subjects. The combination of spin-canting effects and the collection of gadolinium species within small-sized GdIO nanoparticles led to a significantly enhanced T1 contrast effect. For example, GdIO nanoparticles with a diameter of ∼4.8 nm exhibited a high r1 relaxivity of 7.85 mM(-1)·S(-1) and a low r2/r1 ratio of 5.24. After being coated with zwitterionic dopamine sulfonate molecules, the 4.8 nm GdIO nanoparticles showed a steady hydrodynamic diameter (∼5.2 nm) in both PBS buffer and fetal bovine serum solution, indicating a low nonspecific protein absorption. This study provides a valuable strategy for the design of highly sensitive iron-oxide-based T1 contrast agents with relatively long circulation half-lives (∼50 min), efficient tumor passive targeting (SKOV3, human ovarian cancer xenograft tumor as a model), and the possibility of rapid renal clearance after tumor imaging.

Magnetoresistance has been studied in LaFe/sub 11.2/Co/sub 0.7/Si/sub 1.1/ compound. The ferromagnetic ordering at Curie temperature T/sub C/ of 274 K was found being accompanied by a drastic negative lattice expansion due to the strong structural and magnetic interplay. Such a simultaneous magnetic and lattice change would cause changes in transport properties. The measured transport properties indicate that the transition can be induced by temperature or applied magnetic field. The sample shows a metallic character below T/sub C/, whereas the electrical resistance decreases dramatically and then recovers the metal-like behavior above T/sub C/. Application of a magnetic field retains the transitions via increasing the ferromagnetic ordering temperature. An isothermal increase of field leads to an increase of resistance at temperatures near but above T/sub C/, which is a result of the field-induced metamagnetic transition from paramagnetic to ferromagnetic state.

Simple p–n junctions have been fabricated using a simple heteroepitaxial structure of La0.67Ca0.33MnO3−δ/Nb-doped SrTiO3. In such junctions, the La0.67Ca0.33MnO3−δ exhibits semiconductor behavior due to oxygen deficiency, whereas the Nb–0.7 wt %-doped SrTiO3 shows a metal behavior. These junctions demonstrate good rectifying characteristic in a wide temperature range from 5 to 350 K. An intriguing observation is that the rectifying behavior is nearly independent of temperature.

Electric-current-dependent resistance has been studied in epitaxial thin films of La0.7Ca0.3MnO3 and La0.85Ba0.15MnO3. Attention was focused at the influence of the applied dc current on the resistance of these epitaxial thin films in the absence of a magnetic field. A significant change in the ratio of the peak resistance at different currents or current resistance was found to be ∼23%–26% with a current density up to 8×104 Acm−2. For both La0.7Ca0.3MnO3 and La0.85Ba0.15MnO3 compounds, the dependence of the measured resistance on the current revealed a good linear relationship. Although the nature behind such an effect has not been well understood yet, the feature that the resistance in doped manganese oxides could be easily controlled by the electric current should be of interest for various applications such as field effect devices.

A radioactive probe (1) has been developed and applied to a condensation reaction and self-assembly of radioactive nanoparticles (i.e., (125)I-NPs) intracellularly. Upon 160 min cellular efflux, the radioactivity retained in cells incubated with 1 was 4-fold more higher than that of those cells treated with a scrambled control probe (1-Scr).

Monodisperse Gd(2) O(3) -embedded iron oxide (GdIO) nanoparticles can simultaneously enhance the local magnetic field intensities of each other under an external magnetic field and result in synergistic enhancement of T(1) and T(2) effects. GdIO nanoparticles have the unique property to be both T(1) and T(2) contrast agents and can potentially lead to higher accuracy in cancer diagnosis, particularly liver tumors.

Owing to their unique physical and chemical properties, magnetic iron oxide nanoparticles have become a powerful platform in many diverse aspects of biomedicine, including magnetic resonance imaging, drug and gene delivery, biological sensing, and hyperthermia. However, the biomedical applications of magnetic iron oxide nanoparticles arouse serious concerns about their pharmacokinetics, metabolism, and toxicity. In this review, the updated research on the biomedical applications and potential toxicity of magnetic iron oxide nanoparticles is summarized. Much more effort is required to develop magnetic iron oxide nanoparticles with improved biocompatible surface engineering to achieve minimal toxicity, for various applications in biomedicine.

The successful and explosive development of nanotechnology is significantly impacting the fields of biology and medicine. Among the spectacular developments of nanobiotechnology, interest has grown in the use of nanomaterials as nanoprobes for bioanalysis and diagnosis. Herein, we review state-of-the-art nanomaterial-based probes and discuss their applications in in vitro diagnostics (IVD) and challenges in bringing these fields together. Major classes of nanoprobes include quantum dots (QDs), plasmonic nanoparticles, magnetic nanoparticles, nanotubes, nanowires, and multifunctional nanomaterials. With the advantages of high volume/surface ratio, surface tailorability, multifunctionality, and intrinsic properties, nanoprobes have tremendous applications in the areas of biomarker discovery, diagnostics of infectious diseases, and cancer detection. The distinguishing features of nanoprobes for in vitro use, such as harmlessness, ultrasensitivity, multiplicity, and point-of-care use, will bring a bright future of nanodiagnosis.

High-Tc Josephson junctions with a graded barrier have been prepared by using a composite target. Such a barrier is synthesized by utilizing Y1−xPrxBa2Cu3Oy with a continually graded concentration of Pr, in which no lattice mismatch and other incompatible problems take place. The structural interfaces are absent in the weak link region and Josephson coupling occurs at the naturally formed superconducting/normal interfaces within the Y1−xPrxBa2Cu3Oy layer. Thus, it can significantly enhance the reproducibilty and performance of these junctions. The temperature dependences of the barrier thickness and Josephson were also studied.

High quality epitaxial Eu/sub 2/CuO/sub 4/ (ECO) thin films have been deposited on yttrium-stabilized zirconia (YSZ) [100] substrates by magnetron rf sputtering method. The obtained ECO films are highly c-axis-oriented and well crystallized, as shown by x-ray diffraction, rocking curves. The influence of oxygen out-diffusion on the c-axis length and the resistance behavior were studied. The post vacuum annealing removes the excess oxygen from the structure of ECO. As a result, the c-axis length decreases and the resistivity increases. By using ECO as a buffer layer, extremely smooth surface of YBCO was obtained on YSZ substrates.

Near-infrared fluorescence (NIRF) imaging promises to improve cancer imaging and management; advances in nanomaterials allow scientists to combine new nanoparticles with NIRF imaging techniques, thereby fulfilling this promise. Here, we present a synopsis of current developments in NIRF nanoprobes, their use in imaging small living subjects, their pharmacokinetics and toxicity, and finally their integration into multimodal imaging strategies. We also discuss challenges impeding the clinical translation of NIRF nanoprobes for molecular imaging of cancer. Whereas utilization of most NIRF nanoprobes remains at a proof-of-principle stage, optimizing the impact of nanomedicine in cancer patient diagnosis and management will probably be realized through persistent interdisciplinary amalgamation of diverse research fields.

The combination of nanotechnology and molecular biology has developed into an emerging research area: nanobiotechnology. Magnetic nanoparticles are well-established nanomaterials that offer controlled size, ability to be manipulated externally, and enhancement of contrast in magnetic resonance imaging (MRI). As a result, these nanoparticles could have many applications in biology and medicine, including protein purification, drug delivery, and medical imaging. Because of the potential benefits of multimodal functionality in biomedical applications, researchers would like to design and fabricate multifunctional magnetic nanoparticles. Currently, there are two strategies to fabricate magnetic nanoparticle-based multifunctional nanostructures. The first, molecular functionalization, involves attaching antibodies, proteins, and dyes to the magnetic nanoparticles. The other method integrates the magnetic nanoparticles with other functional nanocomponents, such as quantum dots (QDs) or metallic nanoparticles. Because they can exhibit several features synergistically and deliver more than one function simultaneously, such multifunctional magnetic nanoparticles could have unique advantages in biomedical applications. In this Account, we review examples of the design and biomedical application of multifunctional magnetic nanoparticles. After their conjugation with proper ligands, antibodies, or proteins, the biofunctional magnetic nanoparticles exhibit highly selective binding. These results indicate that such nanoparticles could be applied to biological medical problems such as protein purification, bacterial detection, and toxin decorporation. The hybrid nanostructures, which combine magnetic nanoparticles with other nanocomponents, exhibit paramagnetism alongside features such as fluorescence or enhanced optical contrast. Such structures could provide a platform for enhanced medical imaging and controlled drug delivery. We expect that the combination of unique structural characteristics and integrated functions of multicomponent magnetic nanoparticles will attract increasing research interest and could lead to new opportunities in nanomedicine.

Compared with the organic dyes and fluorescent proteins, quantum dots (QDs) show many unique optical properties, such as narrow and tunable emission spectra, superior photostability, high quantum yields, and the capacity of simultaneous excitation of multiple fluorescence colors. The QDs emitting at above 700 nm in the NIR region minimize the problems of indigenous fluorescence of tissues and meet the requirements of in vivo biological imaging applications. However, most of QDs containing cadmium showed potential cytotoxicity under extreme conditions limiting their further applications and clinical translations.Copyright © 2010 by ASME

Nanoparticles that self-assemble on a liquid-liquid interface serve as the building block for making heterodimeric nanostructures. Specifically, hollow iron oxide nanoparticles within hexane form colloidosomes in the aqueous solution of silver nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectrometry, X-ray diffraction, UV-vis spectroscopy, and SQUID were used to characterize the heterodimers. Interestingly, the formation of silver nanoparticles helps the removal of spinglass layer on the hollow iron oxide nanoparticles. This work demonstrates a powerful yet convenient strategy for producing sophisticated, multifunctional nanostructures.

Molecular imaging plays a key role in personalized medicine, which is the goal and future of patient management. Among the various molecular imaging modalities, optical imaging may be the fastest growing area for bioanalysis, and the major reason is the research on fluorescence semiconductor quantum dots (QDs) and dyes have evolved over the past two decades. The great efforts on the synthesis of QDs with fluorescence emission from UV to near-infrared (NIR) regions speed up the studies of QDs as optical probes for in vitro and in vivo molecular imaging. For in vivo applications, the fluorescent emission wavelength ideally should be in a region of the spectrum where blood and tissue absorb minimally and tissue penetration reach maximally, which is NIR region (typically 700-1000 nm). The goal of this review is to provide readers the basics of NIR-emitting QDs, the bioconjugate chemistry of QDs, and their applications for diagnostic tumor imaging. We will also discuss the benefits, challenges, limitations, perspective, and the future scope of NIR-emitting QDs for tumor imaging applications.

We have developed a convenient strategy for preparing color-tunable fluorescent-magnetic core/shell multifunctional nanocrystals, which exhibit excellent photoluminescence (PL) properties (fluorescing tunably from 550 nm to 630 nm by modifying the shell thickness) and ferromagnetic material properties (a magnetization of 4.4 emu g(-1) and a coercivity of 95 Oe).

Most magnetorheological materials, composed of magnetic microparticles in a liquid, require significant amounts of magnetic particles and a large magnetic field to achieve the desired effects. Here, we report on a new type of magnetorheological materials consisting of small amounts of magnetic nanoparticles (0.8 wt %) but exhibiting large rheological change (i.e., a gel–sol transition) upon the application of a small magnetic field. We use self-assembly to create hybrid nanofibers, which consist of supramolecular hydrogelators and magnetic nanoparticles, as the matrices of the hydrogel. Localized in the nanofibers at a distance of 1–2 nm, the magnetic nanoparticles occupy a small volume fraction of the hydrogel, significantly enhancing the magnetic dipole interactions between them, which results in the large magnetoresponse. This strategy generates a hierarchical nanostructure and eliminates several drawbacks of the simple mixture of polymers with nanoparticles, and thus provides a new methodology that uses magnetic force to control the nanostructures and properties of soft materials.

Core-shell nanostructures consisting of FePt magnetic nanoparticles as the core and semiconducting chalcogenides as the shell were synthesized by a series of reactions in a one-pot procedure. Adding Cd(acac)2 as the cadmium precursor to a reaction mixture containing FePt nanoparticles afforded FePt@CdO core-shell intermediates. The subsequent addition of chalcogens yielded FePt@CdX core-shell nanocrystals (where X was S or Se). The reverse sequence of addition, i.e., adding X before Cd, resulted in spongelike nanostructures because the chalcogens readily formed nanowires in the solution. Transmission electron microscopy, energy-dispersive X-ray spectrometry, selected area electron diffraction, fluorescence spectroscopy, and SQUID were used to characterize the nanostructures. These core-shell nanostructures displayed superparamagnetism at room temperature and exhibited fluorescence with quantum yields of 2.3-9.7%. The flexibility in the sequence of addition of reagents, combined with the compatibility of the lattices of the different materials, provides a powerful yet convenient strategy for generating sophisticated, multifunctional nanostructures.

We report the evaluation of cytotoxicity of a new type of engineered nanomaterials, FePt@CoS(2) yolk-shell nanocrystals, synthesized by the mechanism of the Kirkendall effect when FePt nanoparticles serve as the seeds. The cytotoxicity of FePt@CoS(2) yolk-shell nanocrystals, evaluated by MTT assay, shows a much lower IC(50) (35.5 +/- 4.7 ng of Pt/mL for HeLa cell) than that of cisplatin (230 ng of Pt/mL). In the control experiment, cysteine-modified FePt nanoparticles exhibit IC50 at 12.0 +/- 0.9 microg of Pt/mL. Transmission electron microscopy confirms the cellular uptake of FePt@CoS(2) nanocrystals, and the magnetic properties analysis (SQUID) proves the release of FePt nanoparticles from the yolk-shell nanostructures after cellular uptake. These results are significant because almost none of the platinum-based complexes produced for clinical trials in the past 3 decades have shown higher activity than that of the parent drug, cisplatin. The exceptionally high toxicity of FePt@CoS(2) yolk-shell nanocrystals (about 7 times higher than that of cisplatin in terms of Pt) may lead to a new design of an anticancer nanomedicine.

The effects of series resistance in heterojunctions composed of La0.5Ca0.5MnO3 (LCMO) and Nb:SrTiO3 with 0.05 wt.% and 0.7 wt.% of Nb doping (0.05NbSTO and 0.7NbSTO) have been investigated in detail using current–voltage curves with and without light illumination. Two linear plots, namely, dV/dlnJ versus J and H(J)[≡V-(nk B T/q)ln(J/A**T 2)] versus J, have been used to extract the series resistance. These two plots give very close values. The extracted series resistance exhibits a monotonous increase with decreasing temperatures, which could explain the observed anomalous temperature dependence of short circuit current in LCMO/0.7NbSTO.