Tailoring the Surface Functionalities of Radio Frequency Magnetron-Sputtered ZnO Thin Films by Ar/NH3 Gas Mixture Surface-Wave Plasmas.

The surface functionalization of radio frequency magnetron-sputtered zinc oxide (ZnO) thin films tailored by low-pressure Ar/NH3 mixture surface-wave plasmas (SWPs) is discussed based on the results of photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectrophotometric measurements. At an Ar/NH3 gas mixture ratio of 70%/30%, both the PL intensity of the near-band-edge emission and the XRD intensity of the ZnO(002) reflection peak were enhanced by about 5.5 and 8 times, respectively, compared to the values for the as-grown sample. Furthermore, the XPS and spectrophotometric analyses using the fluorescent dye showed that the amine group functionalization over the surface of the ZnO films reached their maximum values at the same gas ratio. From the results of optical emission spectroscopic and ion mass spectrometric measurements in the Ar/NH3 mixture SWPs, it is inferred that the nitrogen-containing reactive species, such as NH x+ ( x = 1-4) ions and NH y ( y = 1, 2) molecules in addition to H radicals might crucially interact with the defective ZnO surface lattices to repair the ZnO thin films from compressive to strain-free crystallized structures, enhance the PL intensity, and produce the amine group surface functionalization.

Copper induced hollow carbon nanospheres by arc discharge method: controlled synthesis and formation mechanism.

Hollow carbon nanospheres with controlled morphologies were synthesized via the copper-carbon direct current arc discharge method by alternating the concentrations of methane in the reactant gas mixture. A self-healing process to keep the structural integrity of encapsulated graphitic shells was evolved gradually by adding methane gas from 0% to 20%. The outer part of the coated layers expanded and hollow nanospheres grew to be large fluffy ones with high methane concentrations from 30% to 50%. A self-repairing function by the reattachment of broken graphitic layers initiated from near-electrode space to distance was also distinctly exhibited. By comparing several comparable metals (e.g. copper, silver, gold, zinc, iron and nickel)-carbon arc discharge products, a catalytic carbon-encapsulation mechanism combined with a core-escaping process has been proposed. Specifically, on the basis of the experimental results, copper could be applied as a unique model for both the catalysis of graphitic encapsulation and as an adequate template for the formation of hollow nanostructures.

Antibody-integrated and functionalized graphite-encapsulated magnetic beads, produced using ammonia gas plasma technology, for capturing Salmonella.

Salmonella spp. is the single and most important causative agent of foodborne infections, especially involving foods such as eggs, milk and meat. To prevent infection, a reliable surveillance system is required that can quickly and sensitively detect Salmonella. Here, we describe the development of antibody-integrated magnetic beads that are functionalized by a novel strategy using ammonia gas plasma. Ammonia plasma, produced by a radio frequency (RF) power supply, was allowed to react with the surface of graphite-encapsulated magnetic beads, resulting in the introduction of amino groups. An anti-Salmonella antibody was then anchored by sulfide groups present on the protein surface to the amino groups of the magnetic beads via N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). The potential usefulness of these magnetic beads for capturing Salmonella was examined as follows. The beads were incubated with Salmonella in liquid medium and then separated from the supernatant by applying a magnetic field. After thorough washing, adsorption of Salmonella to the beads was confirmed by immunochromatography, polymerase chain reaction and a direct culture assay. Our findings indicate that the capture and concentration of Salmonella using the antibody-integrated magnetic beads was more efficient than commercial Dynabeads® anti-Salmonella, which are conventionally used for concentrating Salmonella from liquid cultures. We believe this novel bead technology will contribute to the enhanced detection of Salmonella.

Integration of antibody by surface functionalization of graphite-encapsulated magnetic beads using ammonia gas plasma technology for capturing influenza A virus.

Antibody-integrated magnetic beads have been functionalized for influenza A virus capture. First, ammonia plasma produced by a radio frequency power source was reacted with the surface of graphite-encapsulated magnetic beads to introduce amino groups. Anti-influenza A virus hemagglutinin antibody was then anchored by its surface sulfide groups to the amino groups on the beads via N-succinimidyl 3-(2-pyridyldithio) propionate. After incubation with influenza A virus, adsorption of the virus to the beads was confirmed by immunochromatography, polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and inoculation of chicken embryonated eggs, indicating that virus infectivity is maintained and that the proposed method is useful for the enhanced detection and isolation of influenza A virus.

Design of Chitosan-Grafted Carbon Nanotubes: Evaluation of How the -OH Functional Group Affects Cs+ Adsorption.

In order to explore the effect of -OH functional groups in Cs+ adsorption, we herein used the low temperature plasma-induced grafting method to graft chitosan onto carbon nanotubes (denoted as CTS-g-CNTs), as raw-CNTs have few functional groups and chitosan has a large number of -OH functional groups. The synthesized CTS-g-CNT composites were characterized using different techniques. The effect of -OH functional groups in the Cs+ adsorption process was evaluated by comparison of the adsorption properties of raw-CNTs with and without grafting chitosan. The variation of environmental conditions such as pH and contact time was investigated. A comparison of contaminated seawater and simulated groundwater was also evaluated. The results indicated that: (1) the adsorption of Cs+ ions was strongly dependent on pH and the competitive cations; (2) for CNT-based material, the -OH functional groups have a positive effect on Cs+ removal; (3) simulated contaminated groundwater can be used to model contaminated seawater to evaluate the adsorption property of CNTs-based material. These results showed direct observational evidence on the effect of -OH functional groups for Cs+ adsorption. Our findings are important in providing future directions to design and to choose effective material to remedy the removal of radioactive cesium from contaminated groundwater and seawater, crucial for public health and the human social environment.

Broadband infrared quarter wave plate realized through perpendicular-to-helical-axis wave propagation in a helix array.

The ability of helix arrays to filter circularly polarized light efficiently when the light propagates parallel to the helical axis has been demonstrated recently. In this Letter, we present a broadband linear-to-circular polarization transformer composed of metal microhelices. The device provides significant transformation performance combined with high transmittance over a broad infrared wave band. High performance is achieved through fine adjustment of a finite-element electromagnetic model. The array design assumes wave propagation perpendicular to the helical axis, which distinguishes it from well-studied analogous designs that filter light propagating parallel to the helical axis. To the best of our knowledge, this is the first time this scheme has been realized in the infrared range.

Retraction: A carboxymethyl cellulose modified magnetic bentonite composite for efficient enrichment of radionuclides.

[This retracts the article DOI: 10.1039/C6RA10990J.].

Synthesis of urea-modified magnetic nanocomposites iron oxide/carbon as a potential biomaterial produced by arc discharge in liquid medium and its in-vivo toxicity assessment.

Carbon-encapsulated magnetic nanoparticles are promising candidate materials for drug-delivery applications. However, due to their hydrophobic and aggregation properties, which indicate lower biocompatibility, proper surface modification of the carbon-based material is required. In the present study, we present the facile route to producing biocompatible magnetic nanocomposite iron oxide/carbon using the liquid medium arc-discharge method. The medium used was ethanol 50% with urea added in various concentrations. Using x-ray diffraction (XRD), the nanocomposite produced was confirmed to have a crystalline structure with distinctive peaks representing iron oxide, graphite, and urea. Fourier transform infrared spectroscopy (FTIR) analysis of the nanocomposite produced in ethanol/acetic acid or ethanol/urea medium shows several vibrations, including Fe-O, C-H, C-O, C=C, C-H, O-H, and C-N, which are intended to be the attached aromatic oxygen- and amine-containing functional groups. The nanocomposite particle was observed to have a core-shell structure that had an iron-compound core coated in a carbon shell possibly modified by polymeric urea groups. The presence of these groups suggested that the nanocomposite would be biocompatible with biological entities in the living body. Lastly, the prepared nanocomposite Fe3O4/C-urea underwent an in-vivo acute toxicity assay to confirm its toxicity. The highest dose of 2000 mg kg-1 BW in this study caused no deaths in the test animals even though cell damages were observed, especially in the liver. This highest dose is considered a maximum tolerable dose and is defined as practically non-toxic.

ZnO nanopowder induced light scattering for improved visualization of emission sites in carbon nanotube films and arrays.

We report on ZnO nanopowder induced light scattering for improved visualization of emission sites in carbon nanotube films and arrays. We observed a significant reduction of the internal multiple light scattering phenomena, which are characteristic for ZnO micropowders. The microsized grains of the commercially available ZnO:Zn (P 15) were reduced to the nanometre scale by pulsed laser ablation at an oxygen ambient pressure of 10 kPa. Our investigations show no crystalline change and no shift of the broad green emission peak at 500 nm for the ZnO nanopowder. For the application in field emission displays, we demonstrate the possibility of achieving cathodoluminescence with a fine pitch size of 100 microm of the patterned pixels without requiring additional electron beam focusing and without a black matrix. Moreover, the presented results show the feasibility of employing ZnO nanopowder as a detection material for the phosphorus screen method, which is able to localize emission sites of carbon nanotube films and arrays with an accuracy comparable to scanning anode field emission microscopy.

Efficient recovery and enrichment of infectious rotavirus using separation with antibody-integrated graphite-encapsulated magnetic nanobeads produced by argon/ammonia gas plasma technology.

BACKGROUND: Rotavirus is the representative cause of severe acute gastroenteritis in young children. A characteristic feature of rotavirus is low infectious dose and robustness of the virion, suggesting sanitation and hygiene will have little impact. Thus, development of a vaccine should be given priority. Efficient capture of infectious viruses is an important step in generating a vaccine. Previously, antibody-integrated magnetic nanobeads (MNBs) have been developed for virus capture. This study examines the applicability of this method for infectious rotavirus recovery and enrichment. MATERIALS AND METHODS: Graphite-encapsulated MNBs were treated with radio frequency (RF) excited Ar/NH3 gas mixture plasma to introduce amino groups onto their surfaces. Rotavirus viral protein 7 (VP7) antibody was attached to the surface of MNBs via these amino groups using a coupling agent, N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP). The antibody-integrated MNBs were incubated with rotavirus-infected cell lysate and then separated from the supernatant by applying a magnetic field. After thorough washing, rotavirus was recovered and enrichment analysis done by polymerase chain reaction (PCR), immunochromatography, and an infection analysis using MA104 cells. RESULTS AND DISCUSSION: Immunochromatography and PCR indicate that anti-rotavirus antibody-integrated MNPs efficiently capture rotavirus with the capsid protein and viral RNA. The estimated recovery rate was 80.2% by PCR and 90.0% by infection analysis, while the concentrating factor was 7.9-fold by PCR and 6.7-fold by infection analysis. In addition, the absence of non-specific binding to the antibody-integrated MNPs was confirmed using anti-dengue virus antibody-integrated MNBs as a negative control. CONCLUSION: These results suggest that this capture procedure is a useful tool for recovery and enrichment of infectious rotavirus. Moreover, when combined with a suitable virus assay this capture procedure can increase the sensitivity of rotavirus detection. Therefore, this capture method is a valuable tool for generating vaccines as well as for developing sensitive detection systems for viruses.

Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications.

The highly effective removal of Cs⁺ by low turbidity chitosan-grafted magnetic bentonite.

Chitosan-grafted magnetic bentonite (CS-g-MB) was successfully synthesized via a plasma-induced method. The CS-g-MB composite shows good magnetic properties, low turbidity, and high stability in aqueous solution and exhibits significant adsorption capacity for Cs(+) ions. The adsorption of Cs(+) by CS-g-MB is dependent on both pH and ionic strength. In the presence of Mg(2+), K(+), Li(+), and Na(+) ions, the Cs(+) exchange is constrained in the order of Li(+)≈Mg(2+)

Capture of dengue viruses using antibody-integrated graphite-encapsulated magnetic beads produced using gas plasma technology.

Despite significant advances in medicine, global health is threatened by emerging infectious diseases caused by a number of viruses. Dengue virus (DENV) is a mosquito­borne virus, which can be transmitted to humans via mosquito vectors. Previously, the Ministry of Health, Labour and Welfare in Japan reported the country's first domestically acquired case of dengue fever for almost 70 years. To address this issue, it is important to develop novel technologies for the sensitive detection of DENV. The present study reported on the development of plasma-functionalized, graphite-encapsulated magnetic nanoparticles (GrMNPs) conjugated with anti-DENV antibody for DENV capture. Radiofrequency wave­excited inductively­coupled Ar and ammonia gas plasmas were used to introduce amino groups onto the surface of the GrMNPs. The GrMNPs were then conjugated with an antibody against DENV, and the antibody­integrated magnetic beads were assessed for their ability to capture DENV. Beads incubated in a cell culture medium of DENV­infected mosquito cells were separated from the supernatant by applying a magnetic field and were then washed. The adsorption of DENV serotypes 1­4 onto the beads was confirmed using reverse transcription­polymerase chain reaction, which detected the presence of DENV genomic RNA on the GrMNPs. The methodology described in the present study, which employed the plasma-functionalization of GrMNPs to enable antibody­integration, represents a significant improvement in the detection of DENV.

Characteristics of cesium ion sorption from aqueous solution on bentonite- and carbon nanotube-based composites.

The technology development of Cs(+) capture from aqueous solution is crucial for the disposal of nuclear waste and still remains a significant challenge. Previous researches have been proven that ion exchanges with the cations and hydroxyl exchange are the main sorption mechanisms for Cs(+). Therefore, how important are the cation exchange and the hydroxyl exchange mechanisms to Cs(+) sorption? And whether can we improve the sorption capacity of the material by increasing the amount of hydroxyl groups? With these in mind, we herein designed the chitosan-grafted carbon nanotubes (CS-g-CNTs) and the chitosan-grafted bentonite (CS-g-bentonite) by plasma-induced grafting method. The interactions of Cs(+) with CNTs, bentonite, CS-g-CNTs and CS-g-bentonite composites were investigated. The sorption of Cs(+) is mainly dominated by strong cation exchange in monovalent Group I and divalent Group II. And the cation-exchange mechanism is much more effective than the hydroxyl group exchange. The effect of hydroxyl groups is dependent on the property of the matrix. We cannot improve the Cs adsorption capacity of material for Cs(+) only by increasing the amount of hydroxyl groups in any case. The spatial structure and the cation-exchange capacity of the material are important factors for choosing the sorbent for Cs(+) removal from radioactive waste water.

Preparation of high-performance hydroxide exchange membrane by a novel ablation restriction plasma polymerization approach.

A novel approach of ablation restriction plasma polymerization has been successfully demonstrated for the first time in hydroxide exchange membrane synthesis. The membrane possesses high hydroxide conductivity, alkaline stability, and the ability of fully encompassing catalyst particles, without solubility in low boiling point water-soluble solvents.

Removal of polychlorinated biphenyls from aqueous solutions using beta-cyclodextrin grafted multiwalled carbon nanotubes.

Cyclodextrins have excellent ability in the preconcentration of organic pollutants from aqueous solutions by forming inclusion complexes. Multiwalled carbon nanotubes (MWCNTs) possess high adsorption capacity in the removal of organic pollutants through the formation of conjugated complexes. In this paper, beta-cyclodextrin (beta-CD) was grafted on the surfaces of MWCNTs by using plasma technique. The beta-CD grafted MWCNTs (MWCNT-g-CD) were characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermo gravimetric analysis-differential thermal analysis, and scanning electron microscopy in detail. The prepared MWCNT-g-CD were used to remove polychlorinated biphenyls (PCBs) from aqueous solutions under ambient conditions. The results suggest that MWCNT-g-CD have much higher adsorption capacity than MWCNTs in the removal of PCBs from aqueous solutions. MWCNT-g-CD are suitable materials in the preconcentration and immobilization of PCBs from large volumes of aqueous solutions in environmental pollution cleanup.

Plasma-induced grafting of cyclodextrin onto multiwall carbon nanotube/iron oxides for adsorbent application.

The magnetic composite of beta-cyclodextrin grafted onto multiwalled carbon nanotubes/iron oxides (denoted as MWCNTs/iron oxides/CD) was synthesized using the plasma-induced grafting technique and was developed for the removal of inorganic and organic pollutants from aqueous solutions. The characteristic results of Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and thermogravimetric analysis (TGA) showed that beta-CD was grafted onto the MWCNTs/iron oxides. The grafted beta-CD on the MWCNTs/iron oxides contributed to an enhancement of the adsorption capacity because of the strong abilities of the multiple hydroxyl groups and the inner cores of the hydrophobic cavity in beta-CD to form complexes with metal ions and organic pollutants. MWCNTs/iron oxides/CD can be separated and recovered from solution by magnetic separation. The adsorption of Pb(II) on MWCNTs/iron oxides/CD was found to be dependent on pH, and the adsorption of 1-naphthol was found to be independent of pH. The results show that the magnetic composite of MWCNTs/iron oxides/CD is a promising composite material for the preconcentration and separation of inorganic and organic pollutants from aqueous solutions in environmental pollution cleanup.