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van der Waals heterostructures composed of two-dimensional materials vertically stacked have been extensively studied to develop various multifunctional devices. Here, we report WSe2/graphene heterostructure devices with a top floating gate that can serve as multifunctional devices. They exhibit gate-controlled rectification inversion, rectified nonvolatile memory effects, and multilevel optoelectronic memory effects. Depending on the polarity of the gate voltage pulses (VGp), electrons or holes can be trapped in the floating gate, resulting in rectified nonvolatile memory properties. Furthermore, upon repeated illumination with laser pulses, positive or negative staircase photoconductivity is observed depending on the history of VGp, which is ascribed to the tunneling of electrons or holes between the WSe2 channel and the floating gate. These multifunctional devices can be used to emulate excitatory and inhibitory synapses that have different neurotransmitters. Various synaptic functions, such as potentiation/depression curves and spike-timing-dependent plasticity, have been also implemented using these devices. In particular, 128 optoelectronic memory states with nonlinearity less than 1 can be achieved by controlling applied laser pulses and VGp, suggesting that the WSe2/graphene heterostructure devices with a top floating gate can be applied to optoelectronic synapse devices.

Recently, dynamic Schottky diode or p–n junction-based triboelectric nanogenerators (TENGs) which generate direct current were reported. However, most of them exhibited low output voltage because their semiconducting friction layers were directly constructed on an electrode. In this study, we report a “tribodiffusion-driven” TENG, the working mechanism of which differs from previously reported ones. When n-type MoS2 and p-type polypyrrole (PPy) are in contact, electrons and holes diffuse into PPy and MoS2, respectively, contributing to generating output voltages and currents. To increase the number of charges diffusing across the p–n junction, Ag nanoparticles (NPs) and a piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) layer were placed below MoS2. Additionally, PPy was p-doped using Pt NPs. These MoS2-based TENGs exhibited an instantaneous power density of 14.4 mW cm−2 with an external load resistor of 1 MΩ and a transferred charge density of 0.047 μC cm−2 in a single cycle when charging a capacitor. These values are higher than the previously reported values, demonstrating that tribodiffusion-based TENGs can be regarded as another type of TENG.

This study introduces localized surface plasmon resonance (L-SPR) mediated heating filter membrane (HFM) for inactivating universal viral particles by using the photothermal effect of plasmonic metal nanoparticles (NPs). Plasmonic metal NPs were coated onto filter membrane via a conventional spray-coating method. The surface temperature of the HFM could be controlled to approximately 40–60 °C at room temperature, owing to the photothermal effect of the gold (Au) NPs coated on them, under irradiation by visible light-emitting diodes. Due to the photothermal effect of the HFMs, the virus titer of H1Npdm09 was reduced by > 99.9%, the full inactivation time being 50) assay. Crystal violet staining showed that the infectious samples with photothermal inactivation lost their infectivity against Mardin-Darby Canine Kidney cells. Moreover, photothermal inactivation could also be applied to reduce the infectivity of SARS-CoV-2, showing reduction rate of 99%. We used quantitative reverse transcription polymerase chain reaction (qRT-PCR) techniques to confirm the existence of viral genes on the surface of the HFM. The results of the TCID50 assay, crystal violet staining method, and qRT-PCR showed that the effective and immediate reduction in viral infectivity possibly originated from the denaturation or deformation of membrane proteins and components. This study provides a new, simple, and effective method to inactivate viral infectivity, leading to its potential application in various fields of indoor air quality control and medical science.

Composites were prepared by blending PVDF-TrFE/PEDOT:PSS (weight ratio: 0–60%). The ferroelectric characteristics of PVDF-TrFE can be enhanced by adding PEDOT:PSS.

Optoelectronic memory devices, whose states can be controlled using electrical optical signals, are receiving much attention for their potential applications in image sensing and parallel data transmission and processes. Here, we report MoS2-based devices with top floating gates of Au, graphene, and MoS2. Unlike conventional floating gate memory devices, our devices have the photoresponsive floating gate at the top, acting as a charge trapping layer. Stable and reliable switching with an on/off ratio of ∼106 and a retention time of >104 s is achieved by illumination with 405 nm light pulses as well as application of gate voltage pulses. However, upon illumination with 532 or 635 nm light pulses, multilevel optical memory effects are observed, which are dependent on the wavelength and the optical exposure dosage. In addition, compared to the device employing a graphene floating gate, the device with an MoS2 floating gate is more sensitive to light, suggesting that the multilevel optical memory properties originate from photoexcited carriers in the top floating gate and can be modulated by adjusting the top floating gate materials. The structure of the top floating gate may open up a new way to novel optoelectronic memory devices.

van der Waals heterostructures composed of two-dimensional materials vertically stacked have been extensively studied to develop various multifunctional devices. Here, we report WSe

To prescribe effective antibiotics to patients with bacterial infections in a timely manner and to avoid the misuse of antibiotics, a rapid antimicrobial susceptibility test (AST) is essential. However, conventional AST methods require more than 16 h to provide results; thus, we developed an electrical AST (e-AST) system, which provides results within 6 h. The proposed e-AST is based on an array of 60 aptamer-functionalized capacitance sensors that are comparable to currently available AST panels and a pattern-matching algorithm. The performance of the e-AST was evaluated in comparison with that of broth microdilution as the reference test for clinical strains isolated from septic patients. A total of 4,554 tests using e-AST showed a categorical agreement of 97% with a minor error of 2.2%, major error of 0.38%, and very major error of 0.38%. We expect that the proposed e-AST could potentially aid antimicrobial stewardship efforts and lead to improved patient outcomes.

Total internal reflection fluorescence (TIRF) microscopy, which has about 100-nm axial excitation depth, is the method of choice for nanometer-sectioning imaging for decades. Lately, several new imaging techniques, such as variable angle TIRF microscopy, supercritical-angle fluorescence microscopy, and metal-induced energy transfer imaging, have been proposed to enhance the axial resolution of TIRF. However, all of these methods use high numerical aperture (NA) objectives, and measured images inevitably have small field-of-views (FOVs). Small-FOV can be a serious limitation when multiple cells need to be observed. We propose large-FOV nanometer-sectioning microscopy, which breaks the complementary relations between the depth of focus and axial sectioning by using MIET. Large-FOV imaging is achieved with a low-magnification objective, while nanometer-sectioning is realized utilizing metal-induced energy transfer and biexponential fluorescence lifetime analysis. The feasibility of our proposed method was demonstrated by imaging nanometer-scale distances between the basal membrane of human aortic endothelial cells and a substrate., Hwang et al. demonstrate that a high axial resolution can be achieved even with low numerical aperture (NA) objectives. They show the nano-profile of a basal cell membrane using metal-induced energy transfer and biexponential fluorescence lifetime analysis. The low-NA objective provides a larger field-of-view (FOV), thereby overcoming the limitations of a small FOV of the usually used high-NA objectives.

BackgroundsDespite the advances of rheumatoid arthritis (RA) therapeutics, several patients do not receive adequate treatment due to the toxicity and/or insufficient response of drugs. The aim of this study is to design photothermally controlled drug release from multifunctional nanoparticles (MNPs) at a near-infrared (NIR) irradiated site to improve therapeutic efficacy for RA and reduce side effects.MethodsAu film was deposited onto methotrexate (MTX)-loaded poly(ethylene glycol)-poly(lactic-co-glycolic acid) (PLGA) nanoparticles, resulting in MTX-loaded MNPs. The synergistic effects of MTX-loaded MNPs with NIR irradiation were investigated using RA fibroblast-like synoviocytes (FLSs) and collagen-induced arthritis (CIA) mice.ResultsUpon NIR irradiation, NIR resonance of the Au half-shell generated heat locally, accelerating MTX release from PLGA nanoparticles. In vivo NIR images of MTX-loaded MNPs indicated effective delivery of the MNPs to the inflamed joints. Moreover, in collagen-induced arthritis mice, MTX-loaded MNPs containing 1/1400 of MTX solution (repeated-dose administration) had therapeutic effects comparable to conventional treatment with MTX solution. In vitro experiments showed higher therapeutic efficacy of MTX-loaded MNPs with NIR irradiation than that of chemotherapy alone.ConclusionsA combination therapy of MTX-loaded MNP and NIR irradiation showed durable and good treatment efficacy for the suppression of arthritis in a single administration of small dose of MTX. Our results demonstrate that the treatment modality using drug-loaded MNP with NIR irradiation may be a promising therapeutic strategy for the treatment of RA and allow in vivo NIR optical imaging.

The wettability of graphene has been extensively studied and successfully modified by chemical functionalization. Nevertheless, the unavoidable introduction of undesired defects and the absence of systematic and local control over wettability by previous methods have limited the use of graphene in applications. In addition, microscale patterning, according to wettability, has not been attempted. Here, we demonstrate that the wettability of graphene can be systematically controlled and surface patterned into microscale sections based on wettability without creating significant defects, possible by nondestructive hydrogen plasma. Hydrophobic graphene is progressively converted to hydrophilic hydrogenated graphene (H-Gr) that reaches superhydrophilicity. The great contrast in wettability between graphene and H-Gr makes it possible to selectively position and isolate human breast cancer cells on arrays of micropatterns since strong hydrophilicity facilitates the adsorption of the cells. We believe that our method will provide an essential technique for enabling surface and biological applications requiring microscale patterns with different wettability.

We fabricated MoS2-based flash memory devices by stacking MoS2 and hexagonal boron nitride (hBN) layers on an hBN/Au substrate and demonstrated that these devices can emulate various biological synaptic functions, including potentiation and depression processes, spike-rate-dependent plasticity, and spike-timing dependent plasticity. In particular, compared to a flash memory device prepared on an hBN substrate, the device fabricated on the hBN/Au exhibited considerably more symmetric and linear bidirectional gradual conductance change curves, which may be attributed to the device structure incorporating double floating gate. For the device on the hBN/Au, electron transfers may occur between the floating gate MoS2 and Au, as well as between the floating gate MoS2 and the channel MoS2, allowing for more control over electron tunneling and injection. To test our hypothesis, we also fabricated a MoS2-based flash memory device on an hBN/Pd substrate and found behavior similar to the device fabricated on hBN/Au....

To prevent spread of infection and antibiotic resistance, fast and accurate diagnosis of bacterial infection and subsequent administration of antimicrobial agents are important. However, conventional methods for bacterial detection and antibiotic susceptibility testing (AST) require more than two days, leading to delays that have contributed to an increase in antibiotic-resistant bacteria. Here, we report an aptamer-functionalized capacitance sensor array that can monitor bacterial growth and antibiotic susceptibility in real-time. While E. coli and S. aureus were cultured, the capacitance increased over time, and apparent bacterial growth curves were observed even when 10 CFU/mL bacteria was inoculated. Furthermore, because of the selectivity of aptamers, bacteria could be identified within 1h using the capacitance sensor array functionalized with aptamers. In addition to bacterial growth, antibiotic susceptibility could be monitored in real-time. When bacteria were treated with antibiotics above the minimum inhibitory concentration (MIC), the capacitance decreased because the bacterial growth was inhibited. These results demonstrate that the aptamer-functionalized capacitance sensor array might be applied for rapid ASTs.

We employed modified glass nanocapillaries to investigate interactions between the RNA-binding protein, known as cell carcinoma antigen recognized by T cells-3 (SART3), and the noncoding spliceosome component, U6 small nuclear RNA (snRNA), at the single-molecule level. We functionalized the nanocapillaries with U6 snRNA fragments, which were hybridized to DNA molecules and then covalently attached to the nanocapillary surface. When transported through the modified nanocapillaries, two different SART3-derived constructs, HAT-RRM1-RRM2 and RRM1-RRM2, exhibited resistive ionic current pulses with different dwell times, which represented their different binding affinities to tethered U6 snRNAs. The dissociation constants (KD), estimated from the bias voltage dependence of translocation events, were approximately 1.9 μM and 201 μM for HAT-RRM1-RRM2 and RRM1-RRM2, respectively. These values were comparable to corresponding values obtained with isothermal titration calorimetry, demonstrating that the modified gl...

Optoelectronic memory devices, whose states can be controlled using electrical optical signals, are receiving much attention for their potential applications in image sensing and parallel data transmission and processes. Here, we report MoS

The piezoelectric nanogenerator (PENG) has the potential to become a promising power supply for monitoring and sensors in Internet of Things (IoT) systems through wireless networks. In order to further increase the utilization of energy harvesters in an IoT system, we introduce a novel approach that greatly enhances the piezoelectric output performances by employing the layer-by-layer (LbL) method. Poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) polymer film, which has piezoelectric properties and mechanical flexibility, was used for the active layer in PENG. The maximum open-circuit voltage and closed-circuit current of the LbL multilayer PENG reached 34 V and 100 nA, respectively. In particular, the closed-circuit current of the LbL multilayer PENG was dramatically improved to be five times higher than that of the single-layer PENG. Furthermore, a supercapacitor was employed to investigate the energy storage capability of PENGs using different methods. The proposed LbL multilayer PENG is expected to be a candidate for a promising power supply for self-powered systems in the IoT system.

We developed Schottky junction photovoltaic cells based on multilayer Mo1–xWxSe2 with x = 0, 0.5, and 1. To generate built-in potentials, Pd and Al were used as the source and drain electrodes in a lateral structure, and Pd and graphene were used as the bottom and top electrodes in a vertical structure. These devices exhibited gate-tunable diode-like current rectification and photovoltaic responses. Mo0.5W0.5Se2 Schottky diodes with Pd and Al electrodes exhibited higher photovoltaic efficiency than MoSe2 and WSe2 devices with Pd and Al electrodes, likely because of the greater adjusted band alignment in Mo0.5W0.5Se2 devices. Furthermore, we showed that Mo0.5W0.5Se2-based vertical Schottky diodes yield a power conversion efficiency of ∼16% under 532 nm light and ∼13% under a standard air mass 1.5 spectrum, demonstrating their remarkable potential for photovoltaic applications.

Three-dimensional (3D) cell cultures have recently received attention because they represent a more physiologically relevant environment compared to conventional two-dimensional (2D) cell cultures. However, 2D-based imaging techniques or cell sensors are insufficient for real-time monitoring of cellular behavior in 3D cell culture. Here, we report investigations conducted with a 3D capacitance cell sensor consisting of vertically aligned pairs of electrodes. When GFP-expressing human breast cancer cells (GFP-MCF-7) encapsulated in alginate hydrogel were cultured in a 3D cell culture system, cellular activities, such as cell proliferation and apoptosis at different heights, could be monitored non-invasively and in real-time by measuring the change in capacitance with the 3D capacitance sensor. Moreover, we were able to monitor cell migration of human mesenchymal stem cells (hMSCs) with our 3D capacitance sensor.

We fabricated MoS

Three dimensional (3D) stem cell culture has recently received considerable attention because it may enable the development of in vitro 3D tissue models. In particular, label-free and real-time monitoring of stem cell differentiation is of importance for tissue engineering applications; however, only a few non-invasive monitoring methods are available, especially for 3D cell culture. Here, we describe impedance cell sensors that allowed the monitoring of cellular behaviors in 2D and 3D cell cultures in real-time. Specifically, apparent capacitance peaks appeared in both 2D and 3D cell culture systems when human mesenchymal stem cells (hMSCs) were cultured in osteogenic induction medium. In contrast, when hMSCs were cultured in adipogenic induction medium, the capacitance increased monotonically. In addition, distinct characteristics were noted in the plots of capacitance versus conductance for the cells cultured in osteogenic and adipocyte induction media. These results demonstrated that the differentiation of hMSCs toward osteoblasts and adipocytes in 2D and 3D cell culture systems could be discriminated non-invasively by measuring the real-time capacitance and conductance. Furthermore, the vertical distribution of cellular activities in 3D cell cultures could be monitored in real-time using the 3D impedance cell sensors. Thus, these sensors may be suitable for monitoring the differentiation of various stem cells into different types of cells with distinct dielectric properties for tissue engineering applications.

A precise control and a reliable monitoring tool for the adhesion properties of a cell are very important in atherosclerosis studies. If endothelial cells in contact with the intracellular membrane are not attached securely, low-density lipoprotein (LDL) particles can enter into the inner membrane. It is therefore necessary to measure conditions under which endothelial cell detachment occurs. When a cell is attached to a metal thin film, the lifetime of a fluorescence probe attached to the membrane of the cell is reduced by the metal-induced energy transfer (MIET). Fluorescence lifetime imaging microscopy (FLIM) is used to monitor the attachment condition of a cell to a metal surface using FRET. However, this requires high numerical aperture (NA) objective lens because axial confocal resolution must be smaller than the cell thickness. This requirement limits the field of view of the measurement specimen. In this study we provides a new method which can measure adhesion properties of endothelial cells even with a low NA objective lens by resolving two lifetime components in FLIM.

We describe glass nanocapillaries with single-stranded DNA molecules (ssDNA) covalently attached to the capillary surface. These DNA-functionalized nanocapillaries selectively facilitate the translocation of target ssDNA that is complementary to the probe ssDNA. In addition, the complementary target ssDNA exhibits an event duration time longer than that of the noncomplementary target ssDNA. The temperature dependence measurements of translocation events show that the longer duration time is a result of an interaction between probe and target ssDNA and is dependent on the base pair binding strength. These results demonstrate that single-base mismatch transport selectivity can be achieved using the DNA-functionalized nanocapillaries.

We have developed methotrexate (MTX)-loaded poly(lactic-co-glycolic acid, PLGA) gold (Au)/iron (Fe)/gold (Au) half-shell nanoparticles conjugated with arginine-glycine-aspartic acid (RGD), which can be applied for magnetic targeted chemo-photothermal treatment, and in vivo multimodal imaging of rheumatoid arthritis (RA). Upon near-infrared (NIR) irradiation, local heat is generated at the inflammation region due to the NIR resonance of Au half-shells and MTX release from PLGA nanoparticles is accelerated. The Fe half-shell layer embedded between the Au half-shell layers enables in vivo T2-magnetic resonance (MR) imaging in addition to NIR absorbance imaging. Furthermore, the delivery of the nanoparticles to the inflammation region in collagen-induced arthritic (CIA) mice, and their retention can be enhanced under external magnetic field. When combined with consecutive NIR irradiation and external magnetic field application, these nanoparticles provide enhanced therapeutic effects with an MTX dosages of only 0.05% dosage compared to free MTX therapy for the treatment of RA.

LDL plays an important role in atherosclerotic plaque formation and macrophage differentiation. However, there is no report regarding the oxidation degree of LDL and macrophage differentiation. Our study has shown that the differentiation into M1 or M2 macrophages is related to the lipid oxidation level of LDL. Based on the level of lipid peroxidation, LDL is classified into high-oxidized LDL (hi-oxLDL) and low-oxidized LDL (low-oxLDL). The differentiation profiles of macrophages were determined by surface receptor expression and cytokine secretion profiles. Low-oxLDL induced CD86 expression and production of TNF-αand IL-12p40 in THP-1 cells, indicating an M1 macrophage phenotype. Hi-oxLDL induced mannose receptor expression and production of IL-6 and monocyte chemoattractant protein-1, which mostly match the phenotype of M2 macrophages. Further supporting evidence for an M2 polarization by hi-oxLDL was the induction of LOX-1 in THP-1 cells treated with hi-oxLDL but not with low-oxLDL. Similar results were obtained in primary human monocytes. Therefore, our results strongly suggest that the oxidation degree of LDL influences the differentiation of monocytes into M1 or M2 macrophages and determines the inflammatory fate in early stages of atherosclerosis.

The temperature dependence of electrical transport properties was investigated for multilayered MoS2 field effect transistor devices with thicknesses of 3-22 nm. Some devices showed typical n-type semiconducting behavior, while others exhibited metal-insulator crossover (MIC) from metallic to insulating conduction at finite temperatures. The latter effect occurred near zero gate voltage or at high positive gate voltages. Analysis of Raman spectroscopy revealed the key difference that devices with MIC have a metallic 1T phase as well as a semiconducting 2H phase, whereas devices without the MIC did not have a metallic 1T phase. These results suggest that the metallic 1T phase may contribute to inducing the MIC.

Mesoporous carbon nanofibers (MCNFs) are fabricated at various carbonization temperatures. The carbonization temperature plays a key role in determining the structural characteristics and the electronic properties of MCNFs. The band gap energies of MCNFs are estimated to be 0.080, 0.036, and 0.014 eV at the carbonization temperatures of 600, 900, and 1200 °C, respectively. The MCNF carbonized at 1200 °C has the highest stacking height of graphene planes ( L c ) and the largest number of graphene layers ( L c / d ). Raman data show the intensity ratio of D to G peaks, which is related to the graphene size ( L a ). L a increases with increasing the carbonization temperature. In addition, as the carbonization temperature increases, the conductivity of MCNF increases due to larges values of L c , L a , and L c / d .

To investigate the possibility of treating multidrug-resistant tumors with targeted chemo-photothermal treatment, we conducted in vitro and in vivo studies using a doxorubicin (DOX)-resistant DLD-1 cell line (DLD-1/DOX) and nude mice with human xenograft tumors, respectively. The chemo-photothermal treatment consisted of DOX-loaded-poly(lactic-co-glycolic acid)-Au half-shell nanoparticles with targeting moieties of anti-death receptor-4 monoclonal antibody conjugated to the Au surface. The cells or xenografted tumors treated with nanoparticles were exposed to near infrared light for 10 min, which caused an increase in temperature to 45 °C. Chemo-photothermal treatment resulted in a large reduction in the rate of tumor xenograft growth on DLD-1/DOX tumor-bearing mice with a much smaller dose of DOX than conventional DOX chemotherapy. These results demonstrate that targeted chemo-photothermal treatment can provide high therapeutic efficacy and low toxicity in the treatment of multidrug-resistant tumors.

We performed plasma doping of nitrogen into single-layer graphene on SiO2. Using aluminum oxide as a buffer layer to reduce the plasma damage, up to 19.7% nitrogen was substitutionally doped into graphene. The nitrogen doping of graphene was confirmed by Raman and X-ray photoemission spectroscopy analyses. The n-doping property of the N-doped graphene was measured by Raman spectroscopy. Raman mapping was carried out to statistically confirm the Dirac cone shift of graphene resulting from the N-doping. The Dirac cone shift was directly measured by ultraviolet photoemission spectroscopy (UPS). The UPS result was consistent with the value calculated from the Raman G peak shift.

As a result of industrialization and urbanization, several harmful factors such as the presence of particulate matter (PM) and yellow sand in the atmosphere, have become an issue. As the interest in improving the air quality has increased, the market for high performance air cleaning products able to filter even exceedingly small dust particles is rapidly expanding. In this study, we present a flexible dielectric film that can adsorb PM using triboelectricity. Without the problem of pressure loss or generation of hazardous substances that occurred in previous filters, this polydimethylsiloxane (PDMS)-based flexible dielectric film could be attached to an electric fan and PM can be removed. Triboelectricity is induced by the friction between PDMS and metal nanoparticles when vibration resulting from an external energy source occurs. It was experimentally confirmed that the PM removal efficiency of the PDMS-based flexible dielectric film was 20% higher than that of the control group, based on the standard 95% removal of PM. We expect that the proposed electrostatic film could be used as a highly efficient, flexible, and washable filter in PM removal systems.

We developed MoS2 triboelectric nanogenerators (TENGs) using a large-sized monolayer MoS2 grown by chemical vapor deposition. To investigate the effect of a depletion layer formed across a Schottky or pn junction on the output performance of MoS2 TENGs, three types of TENGs having different contacts, i.e., an ohmic contact, a Schottky contact, and a pn junction, were investigated. During pressing, the TENGs with the Schottky contact and pn junction generated a higher power efficiency than that with the ohmic contact. Additionally, they exhibited self-rectified behaviors. This was ascribed to the diffusion of charges, which resulted in the formation of a depletion layer across the Schottky or pn junction. When ferroelectric polyvinylidene fluoride (PVDF) was used to transfer MoS2, the power efficiency of the TENGs with the Schottky contact or pn junction was further enhanced by the synergistic effect of the depletion layer and the ferroelectric PVDF.

For the treatment of bacteremia, early diagnosis and rapid antibiotic susceptibility tests (ASTs) are necessary because survival chances decrease significantly if the proper antibiotic administration is delayed. However, conventional methods require several days from blood collection to AST as it requires three overnight cultures, including blood culture, subculture, and AST culture. Herein, we report a more rapid method of sensing bacterial growth and AST in blood based on a vertical capacitance sensor functionalized with aptamers. Owing to their vertical structure, the influence of blood cells sunk by gravity on capacitance measurements were minimized. Thus, bacterial growth in blood at 100–103 CFU/mL was monitored in real-time by measuring changes in capacitance at f = 10 kHz. Moreover, real-time capacitance measurements at f = 0.5 kHz provided information on biofilm formation induced during blood cultures. Bacterial growth and biofilm formation are inhibited above the minimal inhibitory concentration of antibiotics; therefore, we also demonstrated that vertical capacitance aptasensors could be applied to rapid AST from positive blood cultures without a need for the subculture process.

CoFe2O4@MnFe2O4, with a mixed core-shell structure was fabricated by a high temperature thermal decomposition. From the Rietveld refinement, these nanoparticles were found to be cubic spinel with space group Fd-3m and with a Bragg factor (R B ) and a structure factor (R F ) less than 5%. The size and the shape of the nanoparticles were examined with high-resolution transmission electron microscopy (HR-TEM). The values of the magnetization (M S ) and the coercivity (H C ) of these nanoparticles at room temperature were 78.95 emu/g and 21.2 mT, respectively. The effect of hyperthermia, measured with a magneTherm device showed that the self-heating temperature of the nanoparticles could reach 133 °C. To determine the applicability of nanoparticles in hyperthermia therapy, we evaluated the in-vitro cell viability of nanoparticles. Based on the probability distribution of cations, we determined the Mossbauer spectra at 4.2 K with two sets of six lines under various applied fields parallel to the direction of the γ-rays. To separate the A and the B sites, we also obtained the Mossbauer spectra of the nanoparticles under high external field up to 5 T at 4.2 K. From the detailed analysis of the Mossbauer spectra, the spin canting angles and the anisotropy energies at the A and the B sites were determined.

Semiconducting SnO2 nanowires deposited with Pd and Sn nanoparticles on their surface are shown to be a highly sensitive hydrogen sensor with fast response time at room temperature. Compared with the SnO2 nanowire deposited with Pd or Sn nanoparticles alone, the Pd/Sn-deposited SnO2 nanowire exhibits a significant improvement in the sensitivity and reversibility of sensing hydrogen gas in the air at room temperature. Our investigation indicates that two factors are responsible for the synergistic effect of Pd/Sn codeposition on SnO2 nanowires. One is that in the presence of Pd the oxidation of Sn nanoparticles on the surface of the SnO2 nanowire is incomplete leading only to suboxides SnOx (1 ≤ x < 2), and the other is that the surface of the Pd/Sn-deposited SnO2 nanowire is almost perfectly hydrophobic.

We developed Schottky junction photovoltaic cells based on multilayer Mo

We fabricated devices consisting of single and double graphene sheets embedded in organic polymer layers. These devices had binary and ternary nonvolatile resistive switching behaviors, respectively. Capacitance–voltage (C–V) curves and scanning capacitance microscopy (SCM) images were obtained to investigate the switching mechanism. The C–V curves exhibited a large hysteresis, implying that the graphene sheets acted as charging and discharging layers and that resistive switching was caused by charges trapped in the graphene layers. In addition, binary capacitive switching behaviors were observed for the device with a single graphene sheet, and ternary capacitive switching behaviors were observed for the device with the double graphene sheets. These results demonstrated that devices consisting of graphene sheets embedded in the polymer layers can be applied to multilevel nonvolatile memcapacitive devices as well as memristive devices.

We investigated the memristive switching behavior in bismuth-antimony alloy (Bi(1-x)Sb(x)) single nanowire devices at 0.1 ≤ x ≤ 0.42. At 0.15 ≤ x ≤ 0.42, most Bi(1-x)Sb(x) single nanowire devices exhibited bipolar resistive switching (RS) behavior with on/off ratios of approximately 10(4) and narrow variations in switching parameters. Moreover, the resistance values in the low-resistance state (LRS) were insensitive to x. On the other hand, at 0.1 ≤ x ≤ 0.15, some Bi(1-x)Sb(x) single nanowire devices showed complementary RS-like behavior, which was ascribed to asymmetric contact properties. Transmission electron microscopy and elemental mapping images of Bi, Sb, and O obtained from the cross sections of the Bi(1-x)Sb(x) single nanowire devices, which were cut before and after RS, revealed that the mobile species was Sb ions, and the migration of the Sb ions to the nanowire surface brought the switch to LRS. In addition, we demonstrated that two types of synaptic plasticity, namely, short-term plasticity and long-term potentiation, could be implemented in Bi(1-x)Sb(x) nanowires by applying a sequence of voltage pulses with different repetition intervals.

We have developed RGD-attached gold (Au) half-shell nanoparticles containing methotrexate (MTX) for the treatment of rheumatoid arthritis (RA), where MTX is the most widely used disease-modifying anti-rheumatic drug (DMARD) for the treatment of RA, and RGD peptide is a targeting moiety for inflammation. Upon near-infrared (NIR) irradiation, heat is locally generated due to Au half-shells, and the drug release rate is enhanced, delivering heat and drug to the inflamed joints simultaneously. RA is a chronic inflammatory disease characterized by synovial inflammation in multiple joints within the penetration depth of NIR light. When combined with NIR irradiation, these nanoparticles containing a much smaller dosage of MTX (1/930 of MTX solution) showed greater therapeutic effects than that of a conventional treatment with MTX solution in collagen-induced arthritic mice. This novel drug delivery system is a good way to maximize therapeutic efficacy and minimize dosage-related MTX side effects in the treatment of RA. Furthermore, these multifunctional nanoparticles could be applied to other DMARDs for RA or other inflammatory diseases.

Transparent conducting multilayer structured electrode of a few nm Ag layer embedded in tin oxide thin film SnO x /Ag/SnO x was fabricated on a glass by RF magnetron sputtering at room temperature. The multilayer of the SnO x (40 nm)/Ag(11 nm)/SnO x (40 nm) electrode shows the maximum optical transmittance of 87.3% at 550 nm and a quite low electrical resistivity of 6.5 × 10 − 5 Ω cm, and the corresponding figure of merit (T 10 /R S ) is equivalent to 3.6 × 10 − 2 Ω − 1 . A normal organic photovoltaic (OPV) structure of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/polythiophene:phenyl-C60-butyric acid methyl ester/Al was fabricated on glass/SnO x /Ag/SnO x to examine the compatibility of OPV as a transparent conducting electrode. Measured characteristic values of open circuit voltage of 0.62 V, saturation current of 8.11 mA/cm 2 and fill factor of 0.54 are analogous to 0.63 V, 8.37 mA/cm 2 and 0.58 of OPV on commercial glass/indium tin oxide (ITO) respectively. A resultant power conversion efficiency of 2.7% is also very comparable with the 3.09% of the same OPV structure on the commercial ITO glass as a reference, and which reveals that SnO x /Ag/SnO x can be appropriate to OPV solar cells as a sound transparent conducting electrode.

nanowires show considerable promise as building blocks for phase-change random access memory (PRAM). Phase-change materials are used in nonvolatile optical memory (e.g., CDs and DVDs), and are being actively inves-tigated as the media in universal solid-state memory devices that combine rapid read and write speeds, high storage density, and non-volatility.

Well-designed photothermal nanomaterials have attractedthe interest of many scientists pursuing a better means toaccurately diagnose cancer and assess the efficacy of treat-ment, because these materials enable therapies in which thetumor region is pin-pointed with a laser-guided light sourcewithout surgical intervention.

We present improved RF circuit modeling of a biosensing element based on a single-walled carbon nanotube combined interdigital capacitors at microwave frequencies. From the resultant circuit, the lumped element values for biomolecular binding are accurately obtained. It is thereby found that the completed RF circuit model shows excellent agreement with measured results. This implies that the electrical properties of a specific biomolecular binding system can be quantitatively analyzed if an optimal RF circuit model is constructed. Finally, we suggest that the suggested methodology can be used to analyze other biomolecular sensing methods.

Receptor-mediated endocytosis is essential for targeted gene/drug delivery to a specific cell type. In this study, we developed a capacitance sensor to monitor receptor-mediated endocytosis in real time. The capacitance sensor was able to detect a capacitance peak in different cell lines during the internalization of adenoviruses or antibodies via receptor-mediated endocytosis. In contrast, the capacitance declined without a capacitance peak when nanoparticles were taken up via non-specific pinocytosis. Thus, our capacitance sensor represents a potential capacitance-based means of discrimination between receptor-mediated endocytosis and non-specific pinocytosis. Moreover, we developed a capacitance sensor array to demonstrate capacitance-based high-throughput screening. We showed that the capacitance sensor array could rapidly identify antibodies or ligands with high specificity for target molecules. We propose that the capacitance sensor array will provide a valuable tool for high-throughput screening.

Pt nanocubes with a size of below 10 nm were synthesized by using various surface-capping agents of polyvinylpyrrolidone (PVP), tetradecyltrimethylammonium bromide (TTAB), and oleylamine with high shape purity. TGA and XPS data revealed the amount and characteristics of the residual organic molecules on the surface of Pt nanocubes. Chemical and thermal stability of these nanoparticles were examined by observing the change of cubic shape upon heating under different chemical environments of N2, H2 and air. The shape change such as rounding of the vertexes or aggregation depended on the type of surface-capping agent and chemical environments. The cubic shape generally started to deform at 200 degrees C and the nanoparticles were mostly fused together at 300 degrees C. The thermal treatment under air produced more PtO layer on the surface with less shape deformation or aggregation when compared with H2 or N2 treatments. Among three surface-capping agents used in this study, oleylamine-capped Pt nanocubes show the highest shape stability with no shape change or aggregation even at 300 degrees C under air.

We fabricated the photoelectrochemical (PEC) cells using n-type TiO 2 and metal (Pt, Pd)-decorated carbon nanotubes (CNTs) as an anode and a cathode, respectively. Photovoltaic effects were clearly observed. Compared with conventional PEC cell with Pt cathode, a larger photo-voltage was found in the PEC cells with the metal-decorated CNT cathode due to p-type semiconducting properties of CNTs. Additionally, we connected two PEC cells in series to decompose water into oxygen and hydrogen. Indeed, the connected PEC cells yielded the photo-voltage of about 1.35 V, which is larger than 1.23 V required for water splitting. This result demonstrates the possibility of hydrogen generation using the connected PEC cells without an external bias.

Glucose/O 2 biofuel cells with an improved power density were developed, using polypyrrole (PPy) nanowires containing glucose oxidase and 8-hydroxyquinoline-5-sulfonic acid hydrate as an anode. The PPy nanowire anode was made by electropolymerizing within the nanopores of an anodized aluminum oxide (AAO) template, and then dissolving the AAO template. The nanowire-type biofuel cell exhibited a higher power density than the film-type biofuel cell by two orders of magnitude; this was likely due to an increase in surface area and enzyme loading. Additionally, we constructed a glucose/O 2 biofuel cell covered with a fluidic channel. Biofuel cells with and without a fluidic channel had comparable performance, demonstrating the feasibility of integrated biofuel cells within a fluidic cell.