Sensitive Detection of BVDV Using Gold Nanoparticle-Modified Few-Layer Black Phosphorus with Affinity Peptide-Based Electrochemical Sensor.

The lethality of the bovine viral diarrhea virus (BVDV) in cattle involves inapparent infection and various, typically subclinical, syndromes. Cattle of all ages are vulnerable to infection with the virus. It also causes considerable economic losses, primarily due to reduced reproductive performance. In the absence of treatment that can completely cure infected animals, detection of BVDV relies on highly sensitive and selective diagnosis methods. In this study, an electrochemical detection system was developed as a useful and sensitive system for the detection of BVDV to suggest the direction of diagnostic technology through the development of conductive nanoparticle synthesis. As a countermeasure, a more sensitive and rapid BVDV detection system was developed using the synthesis of electroconductive nanomaterials black phosphorus (BP) and gold nanoparticle (AuNP). To increase the conductivity effect, AuNP was synthesized on the BP surface, and the stability of BP was improved by using dopamine self-polymerization. Moreover, its characterizations, electrical conductivity, selectivity, and sensitivity toward BVDV also have been investigated. The BP@AuNP-peptide-based BVDV electrochemical sensor exhibited a low detection limit of 0.59 copies mL-1 with high selectivity and long-term stability (retaining 95% of its initial performance over 30 days).

Electrochemical detection of caspase-3 based on a chemically modified M13 phage virus.

Caspase-3, a cysteine-dependent protease, is considered a reliable molecular biomarker for the diagnosis and prognosis of apoptosis-related diseases. In this study, we demonstrated a phage-based electrochemical biosensor for the evaluation of cell apoptosis by the sensitive and specific detection of caspase-3. Specifically, for screening of affinity peptide-displayed phages, phage display was performed using M13 phage libraries (cyclic forms of peptides), and we identified potential affinity peptide-displayed phage clones with the sequence CPTTMWRYC. After characterization of its binding affinity using enzyme-linked immunosorbent assay, whole phage particles were covalently attached to a gold surface using coupling chemistry (MUA-EDC/NHS). The developed phage sensor was characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), electrochemical analysis using cyclic voltammetry (CV), and square wave voltammetry (SWV). Under optimal conditions, the affinity peptide-displayed phage sensor showed a good binding affinity (Kd = 0.13 ± 0.56 µM) and limit of detection (0.39 µM) for caspase-3 detection. Furthermore, developed phage sensor could be monitored the response of apoptotic HeLa cells by detecting caspase-3 activity. This work should stimulate the development of efficient alternative caspase-3 detection methods for the diagnosis and prognosis of apoptosis-related diseases.

A phage virus-based electrochemical biosensor for highly sensitive detection of ovomucoid.

Whole peptide-displayed phage particles are promising alternatives to antibodies in sensor development; however, greater control and functionalization of these particles are required. In this study, we aimed to identify and create highly sensitive and selective phage-based electrochemical biosensors for detecting ovomucoid, a known food allergen. Phage display was performed using two different phage libraries (cyclic and linear form of peptides), which displayed affinity peptides capable of binding specifically to ovomucoid. Throughout the biopanning, two phage clones that displayed both peptides (CTDKASSSC and WWQPYSSAPRWL) were selected. After the characterization of their binding affinities, both whole phage particles were covalently attached to a gold electrode using crosslinking chemistry (MUA-EDC/NHS and Sulfo-LC/SPDP); the developed phage sensor was characterized using cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). The cyclic peptide-displayed phage sensor modified using EDC/NHS chemistry exhibited significantly better binding affinity (Kd = 2.36 ± 0.44 µg/mL) and limit of detection (LOD, 0.12 µg/mL) for ovomucoid than the linear phage sensor, resulting in good reproducibility and recovery, even in an actual egg and white wine samples. This approach may provide an alternative and more efficient way of sensing food allergens with desirable sensitivity, selectivity, and feasibility in food diagnostic applications.

Synergistically strengthened 3D micro-scavenger cage adsorbent for selective removal of radioactive cesium.

A novel microporous three-dimensional pomegranate-like micro-scavenger cage (P-MSC) composite has been synthesized by immobilization of iron phyllosilicates clay onto a Prussian blue (PB)/alginate matrix and tested for the removal of radioactive cesium from aqueous solution. Experimental results show that the adsorption capacity increases with increasing the inactive cesium concentration from 1 ppm to 30 ppm, which may be attributed to greater number of adsorption sites and further increase in the inactive cesium concentration has no effect. The P-MSC composite exhibit maximum adsorption capacity of 108.06 mg of inactive cesium per gram of adsorbent. The adsorption isotherm is better fitted to the Freundlich model than the Langmuir model. In addition, kinetics studies show that the adsorption process is consistent with a pseudo second-order model. Furthermore, at equilibrium, the composite has an outstanding adsorption capacity of 99.24% for the radioactive cesium from aqueous solution. This may be ascribed to the fact that the AIP clay played a substantial role in protecting PB release from the P-MSC composite by cross-linking with alginate to improve the mechanical stability. Excellent adsorption capacity, easy separation, and good selectivity make the adsorbent suitable for the removal of radioactive cesium from seawater around nuclear plants and/or after nuclear accidents.

Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration.

Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties.

Enzymatic formation of carbohydrate rings catalyzed by single-walled carbon nanotubes.

Macrocyclic carbohydrate rings were formed via enzymatic reactions around single-walled carbon nanotubes (SWNTs) as a catalyst. Cyclodextrin glucanotransferase, starch substrate and SWNTs were reacted in buffer solution to yield cyclodextrin (CD) rings wrapped around individual SWNTs. Atomic force microscopy showed the resulting complexes to be rings of 12-50 nm in diameter, which were highly soluble and dispersed in aqueous solution. They were further characterized by Raman and Fourier transform infrared spectroscopy and molecular simulation using density functional theory calculation. In the absence of SWNT, hydrogen bonding between glucose units determines the structure of maltose (the precursor of CD) and produces the curvature along the glucose chain. Wrapping SWNT along the short axis was preferred with curvature in the presence of SWNTs and with the hydrophobic interactions between the SWNTs and CD molecules. This synthetic approach may be useful for the functionalization of carbon nanotubes for development of nanostructures.

Self-assembly of biogenic gold nanoparticles and their use to enhance drug delivery into cells.

Integration of the principles of green chemistry into nanotechnology is one of the key issues in nanobio-science research. There is a growing need for development of a synthesis method for producing environmentally harmless nanoparticles in order to avoid adverse effects in medical applications. Here, we report the use of a simple and rapid in vivo biosynthesis method for the preparation of gold nanoparticles (AuNPs) using heavy metal binding proteins (HMBPs) in recombinant Escherichia coli. The HMBPs were found to act as reducing, stabilizing, and capping agents to form the spherical nanoparticles with 5-20 nm in diameter. The size and the shape of AuNPs were modulated by varying the concentration ratio of recombinant proteins in the medium. Only 20 min was required to form AuNPs at room temperature, suggesting that the reaction rate of the proposed method is faster than that of the chemical methods commonly used for nanoparticle synthesis. The AuNPs could be applied as drug carriers in therapeutic applications to improve drug delivery, since they exhibit higher biocompatibility and less toxic effects than chemically synthesized materials. To achieve high cytotoxicity for cancer chemotherapy, doxorubicin (Dox) was released from AuNPs, which can be a more efficient anti-cancer agent than free Dox.

Surface-concentrated light and efficient carrier collection in microhole-patterned Si solar cells.

We investigate photovoltaic characteristics of crystalline Si solar cells with microhole-patterned surface. We compare patterned samples with different hole-widths and periods with a planar counterpart. From the finite-difference time-domain simulation, the patterned and planar samples are expected to have similar short circuit current density, J(sc) (difference: 1.2%). In contrast, the difference in the measured J(sc) is as large as 12.6%. The simulated optical field patterns reveal that the sample with more significantly concentrated light near the surface has higher quantum efficiency due to more efficient carrier collection. We report the highest efficiency of 15.6% among the hole-patterned solar cells.

Transmission electron microscopy analysis of octanethiol-coated Cu powders.

In this study, microstructures of Cu powders coated with octanethiol were analyzed using (scanning) transmission electron microscopy. Moreover, aging process of the octanethiol-coated layer as time passes by was analyzed using the electron energy loss spectroscopy technique. The octanethiol layer coated on the surface of Cu powders was kept until it was exposed to air for around 30 days. As days passes by, the coating layer had been decomposed and then a Cu(2)O layer was formed on the surface of powders.

A waferscale Si wire solar cell using radial and bulk p-n junctions.

Silicon nanowires (NWs) and microwires (MWs) are cost-effectively integrated on a 4-inch wafer using metal-assisted electroless etching for solar cell applications. MWs are periodically positioned using low-level optical patterning in between a dense array of NWs. A spin-on-doping technique is found to be effective for the formation of heavily doped, thin n-type shells of MWs in which the radial doping profile is easily delineated by low voltage scanning electron microscopy. Controlled tapering of the NWs results in additional optical enhancement via optimization of the tradeoff between increased light trapping (by a graded-refractive-index) and increased reflectance (by decreasing areal density of NWs). Compared to single NW (or MW) arrayed cells, the co-integrated solar cells demonstrate improved photovoltaic characteristics, i.e. a short circuit current of 20.59 mA cm(-2) and a cell conversion efficiency of ∼ 7.19% at AM 1.5G illumination.

Selective adsorption of dithiolate-modified multi-wall carbon nanotubes onto alkanethiol self-assembled monolayers on Au(111).

Dithiolate-modified multi-wall carbon nanotubes (MWCNTs) adsorb selectively on the self-assembled monolayers (SAMs) of alkanethiols on a Au surface: the long dithiolates attached to the MWCNTs anchor the massive MWCNTs onto the Au surface by replacing the shorter thiolates of SAMs.

Functional microscopy tip fabrication by an electric conductive nanowire.

The functional microscopy tip was fabricated by an electric conductive nanowire (NW). Single crystalline nickel silicide (NiSi) NW grown by plasma-enhanced chemical vapor deposition has an excellent electrical conductivity. On behalf of the advantages in tiny size and conductivity of NiSi NW, it was utilized as a nanoscale probe. Dielectrophoretic method was applied to position the NW. The NiSi NW containing solution was dropped in an ac electric field applying system to align the NiSi NW on a Si cantilever. The fabricated NiSi NW-sitting functional microscopy tip obtained the information of topography and electrical signals from a nanoscale structure. It shows the high potential of nanoscale microscopy tip fabrication at reduced processing steps.

A self-assembled fusion protein-based surface plasmon resonance biosensor for rapid diagnosis of severe acute respiratory syndrome.

A surface plasmon resonance (SPR)-based biosensor was developed for simple diagnosis of severe acute respiratory syndrome (SARS) using a protein created by genetically fusing gold binding polypeptides (GBPs) to a SARS coronaviral surface antigen (SCVme). The GBP domain of the fusion protein serves as an anchoring component onto the gold surface, exploiting the gold binding affinity of the domain, whereas the SCVme domain is a recognition element for anti-SCVme antibody, the target analyte in this study. SPR analysis indicated the fusion protein simply and strongly self-immobilized onto the gold surface, through GBP, without surface chemical modification, offering a stable and specific sensing platform for anti-SCVme detection. AFM and SPR imaging analyses demonstrated that anti-SCVme specifically bound to the fusion protein immobilized onto the gold-micropatterned chip, implying that appropriate orientation of bound fusion protein by GBP resulted in optimal exposure of the SCVme domain to the assay solution, resulting in efficient capture of anti-SCVme antibody. The best packing density of the fusion protein onto the SPR chip was achieved at the concentration of 10 microg mL(-1); this density showed the highest detection response (906RU) for anti-SCVme. The fusion protein-coated SPR chip at the best packing density had a lower limit of detection of 200 ng mL(-1) anti-SCVme within 10 min and also allowed selective detection of anti-SCVme with significantly low responses for non-specific mouse IgG at all tested concentrations. The fusion protein provides a simple and effective method for construction of SPR sensing platforms permitting sensitive and selective detection of anti-SCVme antibody.

A nickel silicide nanowire microscopy tip obtains nanoscale information.

An electric conductive Ni silicide nanowire (NiSi NW) embedding electric force microscopy (EFM) tip was fabricated by the dielectrophoretic method and was used to obtain electric information. Due to the geometric and electric excellence, the NiSi NW provides advantages in imaging and fabrication of the microscopy tip. A lead zirconate titanate (PZT) ferroelectric thin film was positively and negatively polarized, and the polarities were obtained by probing of the NiSi NW EFM tip to give distinctive charging information of the PZT film. Moreover, the NiSi NW EFM probing was adopted to achieve the electrical signal from the NW interconnect. The NiSi NW EFM probe confirmed the uniform electric-potential distribution through the NiSi NW interconnect with a small standard deviation. This demonstrates the feasibility of functional utilizations of the NiSi NW.

Photoreactive immobilization of 11-(2,4-dinitro-5-fluorobenzene)undecenamide on a hydrogenated silicon (100) surface for protein immobilizations.

Several nucleophiles such as proteins or poly(ethyleneimine) could be easily conjugated with a 11-(2,4-dinitro-5-fluorobenzene)undecenamide (DFUA) monolayer photochemically prepared on a silicon (100) surface.