An immunoassay using biotinylated single-walled carbon nanotubes as Raman biomarkers

A new immunoassay with biotinylated single-walled carbon nanotubes as persistent, non-photobleaching Raman biomarkers demonstrated excellent sensitivity and specificity.Shvedova AA, 2009, PHARMACOL THERAPEUT, V121, P192, DOI 10.1016/j.pharmthera.2008.10.009Choi JH, 2007, APPL PHYS LETT, V90, DOI 10.1063/1.2745228True LD, 2007, J MOL DIAGN, V9, P7, DOI 10.2353/jmoldx.2007.060186Tian FR, 2006, TOXICOL IN VITRO, V20, P1202, DOI 10.1016/j.tiv.2006.03.008Hwang ES, 2006, NANOTECHNOLOGY, V17, P3442, DOI 10.1088/0957-4484/17/14/016Jeng ES, 2006, NANO LETT, V6, P371, DOI 10.1021/nl051829kHeller DA, 2006, SCIENCE, V311, P508, DOI 10.1126/science.1120792REDDEHASE MJ, 2006, CYTOMEGALOVIRUSES MOHeller DA, 2005, ADV MATER, V17, P2793Varnum SM, 2004, J VIROL, V78, P10960, DOI 10.1128/JVI.78.20.10960-10966.2004Zheng M, 2003, SCIENCE, V302, P1545Saxena V, 2003, J PHARM SCI, V92, P2090, DOI 10.1002/jps.10470Zheng M, 2003, NAT MATER, V2, P338, DOI 10.1038/nmat877Jaiswal JK, 2003, NAT BIOTECHNOL, V21, P47, DOI 10.1038/nbt.767Dresselhaus MS, 2002, ACCOUNTS CHEM RES, V35, P1070, DOI 10.1021/ar0101537O`Connell MJ, 2002, SCIENCE, V297, P593MCCREERY RL, 2002, HDB VIBRATIONAL SPEC, V1, P71Hwang ES, 2000, MICROBIOL IMMUNOL, V44, P827DRESSELHAUS MS, 2000, CARBON, V44, P2000

Sheet resistance characterization of locally anisotropic transparent conductive films made of aligned metal-enriched single-walled carbon nanotubes

One-dimensional conductive fillers such as single-walled carbon nanotubes (SWNTs) can be aggregated and aligned during transparent conductive film (TCF) formation by the vacuum filtration method. The potential error of analysing the average sheet resistance of these anisotropic films, using the four-point probe in-line method and the conversion formula developed assuming uniform isotropic material properties, was systematically investigated by finite element analysis and experiments. The finite element analysis of anisotropic stripe-patterned TCFs with alternating low (r1) and high (r2) resistivities revealed that the estimated average sheet resistance approached r1/t when the probes were parallel to the aligned nanotubes. The thickness of the film is t. It was more close to r2/t when the probes were perpendicular to the aligned tubes. Indeed, TCFs fabricated by the vacuum filtration method using metal-enriched SWNTs exhibited highly anisotropic local regions where tubes were aggregated and aligned. The local sheet resistances of randomly oriented, aligned, and perpendicular tube regions of the TCF at a transmittance of 89.9% were 5000, 2.4, and 12 300 O &1, respectively. Resistivities of the aggregated and aligned tube region (r1 = 1.2 105 O cm) and the region between tubes (r2 = 6.2 102 O cm) could be approximated with the aid of finite element analysis. This work demonstrates the potential error of characterizing the average sheet resistance of anisotropic TCFs using the fourpoint probe in-line method since surprisingly high or low values could be obtained depending on the measurement angle. On the other hand, a better control of aggregation and alignment of nanotubes would realize TCFs with a very small anisotropic resistivity and a high transparency.1221sciescopu

Janus Graphene Oxide Sponges for High-Purity Fast Separation of Both Water-in-Oil and Oil-in-Water Emulsions

Membrane separation of oil and water with high purity and high permeability is of great interest in environmental and industrial processes. However, membranes with fixed wettability can separate only one type of surfactant-stabilized emulsion (water-in-oil or oil-in-water). Here, we report on Janus graphene oxide (J-GO) sponges for high purity and high permeability separation of both water-in-oil and oil-in-water emulsions. Millimeter-scale reduced GO sponges with a controlled pore size (11.2 or 94.1 mu m) are synthesized by freeze drying, and the wettability is further controlled by fluorine (hydrophobic/oleophilic in air) or oxygen (hydrophilic/oleophilic in air) functionalization. J-GO sponges are prepared by the fluorine functionalization on one side and oxygen functionalization on the other side. Interestingly, the oil wettability of oxygen-functionalized surface turns into an oleophobic surface when immersed in water, which is explained by Young's theory. This effect is further used in the separation of both water-in-oil and oil-in-water emulsions by changing the flow direction. The purity of the separated oil and water is very high (>= 99.2%), and the permeability is more than an order of magnitude greater than those of the other Janus membranes reported. J-GO sponges can be reused with an excellent repeatability, demonstrating feasibility in practical applications. © 2017 American Chemical Society131

A Superior Method for Constructing Electrical Percolation Network of Nanocomposite Fibers: In Situ Thermally Reduced Silver Nanoparticles

Nanocomposite fibers, composed of conductive nanoparticles and polymer matrix, are crucial for wearable electronics. However, the nanoparticle mixing approach results in aggregation and dispersion problems. A revolutionary synthesis method by premixing silver precursor ions (silver ammonium acetate) with polyvinyl alcohol is reported here. The solvation of ions-prevented aggregation, and uniformly distributed silver nanoparticles (in situ AgNPs, 77 nm) are formed after thermal reduction (155 degrees C) without using additional reducing or dispersion agents. The conductive fiber is synthesized by the wet spinning technology. After careful optimization, flower-shaped silver nanoparticles (AgNFs, 350-450 nm) are also employed as cofillers. The addition of in situ AgNPs (9.5 vol%) to AgNFs (30 vol%) increases electrical conductivity by 1434% (2090 to 32 064 S cm(-1)) through the efficient construction of percolation networks. The in situ AgNPs provide significantly higher conductivity compared with other secondary nanoparticle fillers. The gaseous byproducts dramatically increase flexibility with a moderate compromise in tensile strength (55 MPa). The particle-free ion-level uniform mixing of silver precursors, followed by in situ reduction, would be a fundamental paradigm shift in nanocomposite synthesis.© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Enhanced water vapor separation by temperature-controlled aligned-multiwalled carbon nanotube membranes

Here we present a new strategy of selectively rejecting water vapor while allowing fast transport of dry gases using temperature-controlled aligned-multiwalled carbon nanotubes (aligned-MWNTs). The mechanism is based on the water vapor condensation at the entry region of nanotubes followed by removing aggregated water droplets at the tip of the superhydrophobic aligned-MWNTs. The first condensation step could be dramatically enhanced by decreasing the nanotube temperature. The permeate-side relative humidity was as low as ∼17% and the helium-water vapor separation factor was as high as 4.62 when a helium-water vapor mixture with a relative humidity of 100% was supplied to the aligned-MWNTs. The flow through the interstitial space of the aligned-MWNTs allowed the permeability of single dry gases an order of magnitude higher than the Knudsen prediction regardless of membrane temperature. The water vapor separation performance of hydrophobic polytetrafluoroethylene membranes could also be significantly enhanced at low temperatures. This work combines the membrane-based separation technology with temperature control to enhance water vapor separation performance. This journal is © The Royal Society of Chemistry1661sciescopu

Ultrahigh Thermal Conductivity of Interface Materials by Silver-Functionalized Carbon Nanotube Phonon Conduits

[No abstract available] © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim132311sciescopu

Silver nanoflowers for single-particle SERS with 10 pM sensitivity

Surface-enhanced Raman scattering (SERS) has received considerable attention as a noninvasive optical sensing technique with ultrahigh sensitivity. While numerous types of metallic particles have been actively investigated as SERS substrates, the development of new SERS agents with high sensitivity and their reliable characterization are still required. Here we report the preparation and characterization of flower-shaped silver (Ag) nanoparticles that exhibit high-sensitivity single-particle SERS performance. Ag nanoflowers (NFs) with bud sizes in the range 220-620 nm were synthesized by the wet synthesis method. The densely packed nanoscale petals with thicknesses in the range 9-22 nm exhibit a large number of hot spots that significantly enhance their plasmonic activity. A single Ag NF particle (530-620 nm) can detect as little as 10(-11) M 4-mercaptobenzoic acid, and thus provides a sensitivity three orders of SERS magnitude greater than that of a spherical Ag nanoparticle. The analytical enhancement factors for single Ag NF particles were found to be as high as 8.0 x 10(9), providing unprecedented high SERS detectivity at the single particle level. Here we present an unambiguous and systematic assessment of the SERS performances of the Ag NFs and demonstrate that they provide highly sensitive sensing platforms by single SERS particle. © 2017 IOP Publishing Ltd Printed in the UK1341sciescopu

Fast mass transport-assisted convective heat transfer through a multi-walled carbon nanotube array

The recently reported fast mass transport through nanochannels provides a unique opportunity to explore nanoscale energy transport. Here we experimentally investigated the convective heat transport of air through vertically aligned multi-walled carbon nanotubes (VAMWNTs). The flow through the unit cell, defined as an interstitial space among four adjacent nanotubes (hydraulic diameter = 84.9 nm), was in the transition (0.62 Knudsen number 0.78) and creeping flow (3.83 x 10(-5) Reynolds number (Re) 1.55 x 10(-4)) regime. The constant heat flux (0.102 or 0.286 W m(-2)) was supplied by a single-mode microwave (2.45 GHz) instantly heating the VAMWNTs. The volume flow rate was two orders of magnitude greater than the Hagen-Poiseuille theory value. The experimentally determined convective heat transfer coefficient (h, 3.70 x 10(-4)-4.01 x 10(-3) W m(-2) K-1) and Nusselt number (Nu, 1.17 x 10(-9)-1.26 x 10(-8)) were small partly due to the small Re. A further increase in Re (2.12 x 10(-3)) with the support of a polytetrafluoroethylene mesh significantly increased h (5.48 x 10(-2) W m(-2) K-1) and Nu (2.37 x 10(-7)). A large number of nanochannels in a given cross-section of heat sinks may enhance the heat dissipation significantly. © The Royal Society of Chemistry 201

Hierarchically Structured Hole Transport Layers of Spiro-OMeTAD and Multiwalled Carbon Nanotubes for Perovskite Solar Cells

The low electrical conductivity of spiro-OMeTAD hole transport layers impedes further enhancements of the power conversion efficiency (PCE) of perovskite solar cells. We embedded multiwalled carbon nanotubes (MWNTs) in spiro-OMeTAD (spiro-OMeTAD/MWNTs) to increase carrier mobility and conductivity. However, direct electrical contact between CH3NH3PbI3 and the MWNTs created pathways for undesirable back-electron transfer, owing to the large work function of MWNTs, limiting enhancements of the PCE. A hierarchical structure of pure spiro-OMeTAD and spiro-OMeTAD/MWNTs was designed to block back-electron transfer and fully exploit the enhanced charge transport of spiro-OMeTAD/MWNTs. The enhanced fill factor, short-circuit current density, open-circuit voltage, and PCE (15.1) were achieved by using this hierarchical hole transport layer structure (MWNT concentration=2wt). The perovskite solar cells were fabricated by a lowerature solution process, further decreasing their per-Watt cost. Respect the hierarchy! Multiwalled carbon nanotubes (MWNTs) are embedded in spiro-OMeTAD to improve electrical conductivity. Perovskite solar cells employing a hierarchical hole transport layer (HTL) structure, comprising pure spiro-OMeTAD and spiro-OMeTAD/MWNT layers, show better blocking of back-electron transfer while fully exploiting the enhanced conductivity of the spiro-OMeTAD/MWNT material. The power conversion efficiency of these perovskite solar cells is improved, to 15.1. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim124241sciescopu