Label-free detection of Cu(II) in a human serum sample by using a prion protein-immobilized FET sensor.

We have developed a field effect transistor (FET) sensor to sensitively detect copper ions (Cu(2+)) in a human serum (HS) sample for promising health-care diagnosis. By utilizing a Cu(2+)-binding prion protein that was immobilized on the FET gate surface, such an FET sensor can provide a simple, label free and highly selective performance, even in HS samples. We demonstrated the sensitivity of the sensor at the nanomolar level, 0-100 nM, which is very useful for the detection range of Cu(2+) deficiency in practical applications.

Field-effect transistor biosensor with signal amplification by ternary initiation complexes for detection of wide-range RNA concentration.

Electrical detection of RNAs using transistor-based biosensors has attracted attention as a strategy for medical diagnosis and environmental monitoring. Herein, we demonstrated a proof-of-concept for specific, sensitive, and label-free RNA detection using a field-effect transistor (FET) biosensor with signal amplification by ternary initiation complexes (SATIC), which is an isothermal one-step nucleic acid amplification initiated by the combination of target RNA, circular DNA template and DNA primer. The SATIC system-applied FET biosensor specifically and quantitatively detected the target RNA with a single-nucleotide difference via the negative charges derived from the amplification products formed by a nucleic acid amplification reaction with φ29 DNA polymerase on the gate surface. In particular, the control of the amplification time allowed the detection of target RNA molecules over a wide concentration range, resulting in a detection limit of up to 6 copies/µL. Therefore, a transistor-based bioassay using the SATIC system could be useful for simple and sensitive nucleic acid analysis.

Attomolar detection of influenza A virus hemagglutinin human H1 and avian H5 using glycan-blotted field effect transistor biosensor.

Influenza virus, through cell invasion and propagation with the interaction between hemagglutinin (HA) present on its surface and glycans on the host cell, causes a rapidly spreading infection throughout the world. In the present investigation, we succeeded for the first time in the attomolar-level sensing and discrimination of influenza A viral HA molecules H1 and H5 by using a glycan-immobilized field effect transistor (FET) biosensor. The small ligand glycans immobilized on the FET device, which make effective use of the charge-detectable region for FET-based detection in terms of Debye length, gave an advantage in the highly sensitive detection of the proteins. Two kinds of trisaccharides receptors terminating in sialic acid-α2,6-galactose (6'-sialyllactose) and in sialic acid-α2,3-galactose (3'-sialyllactose) were conjugated directly with the SiO2 surface of FET devices by a simple glycoblotting method using the self-assembled monolayer (SAM) of aminooxy terminated silane-coupling reagent, 3-aminooxypropyltriethoxysilane. Furthermore, it was demonstrated that the FETs with densely immobilized glycans, which possess the high capture ability by achieving the glycoside cluster effect, clearly distinguish HA molecules between their subtypes H1 (human) and H5 (avian) at the attomolar level, while the conventional method based on HA antibodies achieves only picomolar-level detection. Our findings indicate that the glycan-immobilized FET is a promising device to detect various pathogenic bacteria and viruses through glycan-protein interaction found ubiquitously in many infectious diseases.

Excess heat production in the redox couple reaction of ferricyanide and ferrocyanide.

In order to establish the universality of the excess heat production in electrochemical reaction, under a high magnetic field, as one of the most fundamental electrochemical reactions, the case of ferricyanide-ferrocyanide redox reaction was examined, where ionic vacancies with ± 1 unit charge were collided by means of magnetohydrodynamic (MHD) flow. As a result, from the pair annihilation of the vacancies with opposite signs, beyond 7 T, excess heat production up to 25 kJ·mol-1 in average at 15 T was observed, which was attributed to the liberation of the solvation energy stored in a pair of the vacancy cores with a 0.32 nm radius, i.e., 112 kJ·mol-1. Difference between the observed and expected energies comes from the small collision efficiency of 0.22 due to small radius of the vacancy core. Ionic vacancy initially created as a by-product of electrode reaction is unstable in solution phase, stabilized by releasing solvation energy. Ionic vacancy utilizes the energy to enlarge the core and stores the energy in it. As a result, solvated ionic vacancy consists of a polarized free space of the enlarged core surrounded by oppositely charged ionic cloud. The accuracy and precision of the measured values were ascertained by in situ standard additive method.

Glycan-immobilized dual-channel field effect transistor biosensor for the rapid identification of pandemic influenza viral particles.

Pandemic influenza, triggered by the mutation of a highly pathogenic avian influenza virus (IFV), has caused considerable damage to public health. In order to identify such pandemic IFVs, antibodies that specifically recognize viral surface proteins have been widely used. However, since the analysis of a newly discovered virus is time consuming, this delays the availability of suitable detection antibodies, making this approach unsuitable for the early identification of pandemic IFVs. Here we propose a label-free semiconductor-based biosensor functionalized with sialic-acid-containing glycans for the rapid identification of the pandemic IFVs present in biological fluids. Specific glycans are able to recognize wild-type human and avian IFVs, suggesting that they are useful in discovering pandemic IFVs at the early stages of an outbreak. We successfully demonstrated that a dual-channel integrated FET biosensing system, which were modified with 6'-sialyllactose and 3'-sialyllactose for each gate area, can directly and specifically detect human H1N1 and avian H5N1 IFV particles, respectively, present in nasal mucus. Furthermore, to examine the possibility of identifying pandemic IFVs, the signal attributed to the detection of Newcastle disease virus (NDV) particles, which was selected as a prime model of a pandemic IFV, was clearly observed from both sensing gates. Our findings suggest that the proposed glycan-immobilized sensing system could be useful in identifying new pandemic IFVs at the source of an outbreak.

On-chip fuel cell: micro direct methanol fuel cell of an air-breathing, membraneless, and monolithic design.

This paper proposes a novel design for a microfuel cell as an on-chip power source and demonstrates its fabrication and operation to prove the concept. Its simple design is important from the viewpoints of fabrication (e.g., replication), integration, and compatibility with other microdevices. In testing, the prototype cell was able to generate electric power (maximum: ca. 1.4 microW) on methanol without pumps under both neutral and acidic conditions. As for the size, the electrode part of the cell (two cathodes and one anode) is 400 microns in width and 6 mm in length. The evaluation demonstrated that the proposed design is a promising on-chip power source for miniature devices.

Preparation of human immune effector T cells containing iron-oxide nanoparticles.

Preparation of human immune T cells containing iron-oxide nanoparticles was carried out for the development of magnetically mediated immunotherapy. Peripheral blood lymphocytes (PBLs) after the incubation with magnetite nanoparticles were found to contain measurable ferric ions, which suggested the incorporation of magnetite nanoparticles. Transmission electron microscopic (TEM) study indicated that the incorporation of magnetite nanoparticles was mediated by endocytosis of PBLs. Furthermore, the effects of dosages and diameter of magnetite nanoparticles on the magnetite incorporation were investigated, and it was demonstrated that the increase in dosage promoted the incorporation of nanoparticles and the uptake into PBLs was more effective for magnetite nanoparticles, which formed smaller aggregations in medium. Finally, the demonstration of magnetite incorporation into enriched T cells and tumor antigen-specific cytotoxic T lymphocyte (CTL) line promises the achievement of magnetically mediated immunotherapy with tumor-specific CTLs containing magnetic nanoparticles.

Perpendicular mesoporous Pt thin films: electrodeposition from titania nanopillars and their electrochemical properties.

A perpendicular mesoporous platinum electrode with a flat surface is successfully synthesized by electrodeposition using titania nanopillars as template, and the electrochemical studies indicate that this material is a promising catalytic electrode for fuel cells because of its high surface area and perpendicular nanopores.

Synthesis of Fe3O4 nanoparticles with various sizes and magnetic properties by controlled hydrolysis.

Nanoparticles of Fe(3)O(4) were synthesized by hydrolysis in an aqueous solution containing ferrous and ferric salts at various ratios with 1,6-hexanediamine as a base. It was found that the ferrous to ferric ratio influences the reaction mechanism for the formation of Fe(3)O(4). When the ratio of ferrous to ferric ions was increased, the formation of large hydroxide particles as a precursor of Fe(3)O(4) was promoted, which resulted in an increase in the size of Fe(3)O(4) nanoparticles. As a result, the mean diameter of Fe(3)O(4) nanoparticles increased from approximately 9 to approximately 37 nm as the molar percentage of ferrous ions with respect to the total iron ions was increased from 33 to 100%. Furthermore, it was demonstrated that magnetic properties of Fe(3)O(4) nanoparticles can be controlled by adjusting the molar ratio of ferrous to ferric ions as well as the particle diameter.

Effective induction of death in mesothelioma cells with magnetite nanoparticles under an alternating magnetic field.

With the objective of finding an avenue for development of magnetic hyperthermia as an effective mesothelioma treatment, the influence of heating by magnetite nanoparticles (MNPs) with a diameter of ~40nm, which were incorporated into cells and then subjected to AC magnetic field, on induction of cell death was investigated in all three histological subtypes of human mesothelioma cells (i.e., epithelioid NCI-H28, sarcomatoid NCI-H2052, and biphasic MSTO-211H cells). Cellular uptake of MNPs was observed in all cell types, but the amount of MNPs incorporated per cell into MSTO-211H cells was smaller than in NCI-H28 and NCI-H2052 cells. On the other hand, cell death induced by cellular uptake of MNPs was observed specifically in MSTO-211H cells. Hence, when cells are heated by intracellular MNPs under AC magnetic field, a high degree of cell mortality in NCI-H28 and NCI-H2052 cells is induced by the temperature increase derived from the high amount of intracellular MNPs, but the combination of intracellular heating and cell-type-specific toxicity of MNPs induced high rates of cell death in MSTO-211H cells even at a lower temperature. Almost all of the heated cells were dead after 24-h incubation at 37°C in all histological subtypes. Additionally, higher mortalities were observed in all three types of mesothelioma cells after MNPs-heating, as compared to the heating with a thermostatic bath. Herein, the significance of cellular uptake of MNPs for effectively inducing cell death in mesothelioma has been demonstrated in vitro.

Fabrication of photo-electrochemical biosensors for ultrasensitive screening of mono-bioactive molecules: the effect of geometrical structures and crystal surfaces.

The controlled design of biosensors based on the photo-electrochemical technique with high selectivity, sensitivity, and rapid response for monitoring of mono-bioactive molecules, particularly dopamine (DA) levels in neuronal cells is highly necessary for clinical diagnosis. Hierarchical carbon-, nitrogen-doped (CN) nickel oxide spear thistle (ST) flowers associated in single-heads (S), and symmetric and asymmetric-double heads (D and A, respectively) that are tightly connected through a micrometric dipole-like rod or trunk were fabricated by using a simple synthetic protocol. The CN-ST flower heads were decorated with dense nano-tubular like hedgehog needle skins in vertical alignments. These designated architectures are key features for creating biosensor surface electrodes for photo-electrochemical, ultrasensitive screening of mono-bioactive molecules. The exceptional electrode designs produced numerous catalytically active sites, large surface area, and high electron-transfer mobility. The active coating of carbon-nitrogen nanospheres significantly enhanced the photo-electrocatalytic activity of the prepared biosensor electrodes and prevented leakage of photocatalytic activity under long-term exposure to irradiation. Among all photo-electrochemical assays, the biosensors showed significant sensitivity and selectivity for DA in the presence of interfering molecules such as ascorbic acid (AA), uric acid (UA), adrenaline (A), and noradrenaline (NA). The photo-electrochemical property of the CN-SST-{110} crystal surface electrode showed significant sensing performance for DA in terms of unimpeded diffusion pathways, a wide concentration-detection range, and a low detection limit, even in the presence of potentially interfering molecules compared with other electrode-modified CN-DST-{111} and CN-AST-{101} crystal surfaces. Furthermore, the CN-SST photo-biosensor electrode shows potential in the selective and sensitive determination of DA in real samples, such as human serum and secreted DA from living cells. This finding indicates that the hierarchical ST biosensor may enable analytical discrimination and monitoring of DA and can be employed for clinical diagnosis application.

Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy.

Despite magnetic nanoparticles having shown great potential in cancer treatment, tremendous challenges related to diagnostic sensitivity and treatment efficacy for clinical application remain. Herein, we designed optimized multifunctional magnetite nanoparticles (AHP@MNPs), composed of Fe3O4 nanoparticles and photosensitizer conjugated hyaluronic acid (AHP), to achieve enhanced tumor diagnosis and therapy. Fe3O4 nanoparticles (MNPs) were synthesized by a facile hydrolysis method. MNPs have higher biocompatibility, controllable particle sizes, and desirable magnetic properties. The fabricated AHP@MNPs have enhanced water solubility (average size: 108.13 ± 1.08 nm), heat generation properties, and singlet oxygen generation properties upon magnetic and laser irradiation. The AHP@MNPs can target tumors via CD44 receptor-mediated endocytosis, which have enhanced tumor therapeutic effects through photodynamic/hyperthermia-combined treatment without any drugs. We successfully detected tumors implanted in mice via magnetic resonance imaging and optical imaging. Furthermore, we demonstrated the photodynamic/hyperthermia-combined therapeutic efficacy of AHP@MNPs with synergistically enhanced efficacy against cancer.

Lifetime of Ionic Vacancy Created in Redox Electrode Reaction Measured by Cyclotron MHD Electrode.

The lifetimes of ionic vacancies created in ferricyanide-ferrocyanide redox reaction have been first measured by means of cyclotron magnetohydrodynamic electrode, which is composed of coaxial cylinders partly exposed as electrodes and placed vertically in an electrolytic solution under a vertical magnetic field, so that induced Lorentz force makes ionic vacancies circulate together with the solution along the circumferences. At low magnetic fields, due to low velocities, ionic vacancies once created become extinct on the way of returning, whereas at high magnetic fields, in enhanced velocities, they can come back to their initial birthplaces. Detecting the difference between these two states, we can measure the lifetime of ionic vacancy. As a result, the lifetimes of ionic vacancies created in the oxidation and reduction are the same, and the intrinsic lifetime is 1.25 s, and the formation time of nanobubble from the collision of ionic vacancies is 6.5 ms.

Correction: Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy.

Correction for 'Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy' by Kyoung Sub Kim, et al., Nanoscale, 2016, DOI: 10.1039/c6nr02273a.

High efficiency electrochemical immuno sensors using 3D comb electrodes.

To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (3D) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 microm in width and 30 microm in height, with 20 microm spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated.

Area-selective formation of macropore array by anisotropic electrochemical etching on an n-Si(100) surface in aqueous HF solution.

A photoassisted anodization process to fabricate arrays of uniform and straight macropores at selected areas of a Si wafer surface was developed. The front- and backside surfaces of n-type Si(100) wafers were coated with a thin Si(3)N(4) layer, and the frontside layer was micro-patterned using photolithography and reactive ion etching to form an array of microscopic openings at selected areas. The inverted pyramid-shape micropits were formed at these openings by anisotropic etching using aqueous KOH solution; these pits act as the initiation sites for the anodization to form macropores. The electrochemical etching was carried out in aqueous HF solution under illumination from the backside of the wafer, on which Au/Cr electric contact was formed following removal of the Si(3)N(4) layer. To improve the uniformity of the formation condition of the macropores at the selected area, holes were area-selectively generated by controlling the illumination condition during the anodization. For this, micropatterns were formed on the Au/Cr layer at the backside surface, which were aligned to those at the frontside surface. The parameters, such as HF concentration, current density, and wafer thickness, i.e., hole diffusion length, were optimized, and the arrays of uniform and high-aspect-ratio macropores were formed at the selected area of the domain at the silicon surface.

Fabrication of amino silane-coated microchip for DNA extraction from whole blood.

A simple microchip device for DNA extraction was constructed based on electrostatic interactions between surface amine groups and DNA. Microchannel was fabricated on silicon wafer by photolithography and coated with 3-aminopropyltriethoxysilane (APTES) or 3-[2-(2-aminoethylamino)-ethylamino]-propyltrimethoxysilane (AEEA) to introduce amine groups on the surface. Determination of the number of surface amine groups and optimization of DNA capture condition were demonstrated to characterize the microchip. Capacities of capturing DNA were approximately 97 ng/cm2 in APTES and 194 ng/cm2 in AEEA modified microchips, respectively. The amount of DNA captured in the microchip increased depending on surface amine density. Furthermore, DNA extraction using amine-coated microchip from whole blood was examined. Quantification of DNA and proteins in washing or eluting fraction indicates that proteins were removed at washing steps and only DNA was effectively eluted by changing alkalinity of buffer from pH 7.5 to 10.6. The amount of DNA extracted from whole blood was approximately 10 ng and its recovery ratio was 27-40%. Performance of PCR for the eluted fraction indicates that DNA extracted from whole blood was well purified using amine-coated microchip.

Li-rich Li-Si alloy as a lithium-containing negative electrode material towards high energy lithium-ion batteries.

Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

Induction of Cell Death in Mesothelioma Cells by Magnetite Nanoparticles.

Nanoparticle uptake and cell death following addition of magnetite nanoparticles (MNPs) with a diameter of ∼10 nm were evaluated in three histological types of human mesothelioma cells, NCI-H28 (epithelioid), NCI-H2052 (sarcomatoid), and MSTO-211H (biphasic) cells, and human breast cancer MCF-7 cells. Dose-dependent cell death was observed in MSTO-211H cells but not in MCF-7 cells, although cellular uptake of MNPs was observed in both cell types. Mesothelioma NCI-H28 and NCI-H2052 cells showed behavior more similar to that of breast cancer MCF-7 cells than that of mesothelioma MSTO-211H cells. DNA fragmentation and microarray analyses suggested that MNPs induced transforming growth factor ß2 related apoptosis in MSTO-211H cells. On the other hand, the viability of human mesothelioma cells containing MNPs with a diameter of ∼40 nm was investigated after exposure to an alternating magnetic field. Temperature increase under the alternating magnetic field and high rates of cell death were observed in all three histological types of human mesothelioma.

Sensitive electrical detection of human prion proteins using field effect transistor biosensor with dual-ligand binding amplification.

Simple and accurate detection of prion proteins in biological samples is of utmost importance in recent years. In this study, we developed a label-free electrical detection-based field effect transistor (FET) biosensor using thiamine as a probe molecule for a non-invasive and specific test of human prion protein detection. We found that thiamine-immobilized FETs can be used to observe the prion protein oligomer, and might be a significant test for the early diagnosis of prion-related diseases. The thiamine-immobilized FET was also demonstrated for the detection of prion proteins in blood serum without any complex pre-treatments. Furthermore, we designed a dual-ligand binding approach by the addition of metal ions as a second ligand to bind with the adsorbed prion protein on the thiamine-immobilized surface. When the prion attached to metal ions, the additional positive charge was induced on the gate surface of the FET. This approach was capable of amplifying the magnitude of the FET response and of enhancing the sensitivity of the FET biosensor. Detection of prion proteins has achieved the required concentration for clinical diagnosis in blood serum, which is less than 2 nM. In summary, this FET biosensor was successfully applied to prion detection and proved useful as a simple, fast, sensitive and low-cost method towards a mass-scale and routine blood screening-based test.