The translocation of single-walled carbon nanotubes (SWNTs) across MCF7 breast cancer cells was demonstrated with radioisotope labeling. Hybrids of SWNT−RNA polymer poly(rU) were formed through a nonspecific binding mechanism which could allow for the dissociation of the poly(rU) from the SWNTs upon delivery. The cellular uptake of the hybrids was examined by confocal fluorescence microscopy. Through cell growth and MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assays, we showed the negligible cytotoxicity of SWNTs (up to 0.5 mg/mL) to MCF7 cells.

Single-walled carbon nanotubes (SWNTs), being hydrophobic by nature, aggregate in water to form large bundles. However, isolated SWNTs possess unique physical and chemical properties that are desirable for sensing and biological applications. Conventionally isolated SWNTs can be obtained by wrapping the tubes with biopolymers or surfactants. The binding modes proposed for these solubilization schemes, however, are less than comprehensive. Here we characterize the efficacies of solubilizing SWNTs through various types of phospholipids and other amphiphilic surfactants. Specifically, we demonstrate that lysophospholipids, or single-chained phospholipids offer unprecedented solubility for SWNTs, while double-chained phospholipids are ineffective in rendering SWNTs soluble. Using transmission electron microscopy (TEM) we show that lysophospholipids wrap SWNTs as striations whose size and regularity are affected by the polarity of the lysophospholipids. We further show that wrapping is only observed when SWNTs are in the lipid phase and not the vacuum phase, suggesting that the environment has a pertinent role in the binding process. Our findings shed light on the debate over the binding mechanism of amphiphilic polymers and cylindrical nanostructures and have implications on the design of novel supramolecular complexes and nanodevices.

No abstract

In this paper, a high-performance large-scale flexible heater based on graphene and silver particles is described. The graphene-based heater can be integrated into various systems without having to be too selective about the substrate used. When silver particles are mixed with graphene, the sheet resistance is greatly reduced to 158.7 U sq the advantages of a low driving voltage, high steady-state temperature, ultrafast response and excellent flexibility, the graphene-based heater is expected to be a promising potential candidate for various wearable heating applications.

Density gradient centrifugation is a high-resolution technique for the separation and characterization of large molecules and stable complexes. We have analyzed various nanotube structures by preparative centrifugation in sodium metatungstate-water solutions. Bundled, isolated and acid-treated single-walled nanotubes (SWNTs) and multiwall nanotubes (MWNTs) formed sharp bands at well-defined densities. The structure of the material in each band was confirmed by transmission electron microscopy and Raman spectroscopy. Our data suggest respective densities of 1.87, 2.13, 1.74, and 2.1 g/cm(3) for bundled, isolated, and acid-treated SWNTs and MWNTs. These measured results compare well with their calculated densities.

Owing to the fascinating properties of graphene, fulfilling the promising characteristics of graphene in applications has ignited enormous scientific and industrial interest. Chemical vapor deposition (CVD) growth of graphene on metal substrates provides tantalizing opportunities for the large‐area synthesis of graphene in a controllable manner. However, the tedious transfer of graphene from metal substrates onto desired substrates remains inevitable, and cracks of graphene membrane, transfer‐induced doping, wrinkles as well as surface contamination can be incurred during the transfer, which highly degrade the performance of graphene. Furthermore, new issues can arise when moving to large‐scale transfer at an industrial scale, thus cost‐efficient and environment‐friendly transfer techniques also become imperative. The aim of this review is to provide a comprehensive understanding of transfer‐related issues and the corresponding experimental solutions and to provide an outlook for future transfer techniques of CVD graphene films on an industrial scale.

No abstract

In order to conquer the short-channel effects that limit conventional ultra-scale semiconductor devices, two-dimensional materials, as an option of ultimate thin channels, receive wide attention. Graphene, in particular, bears great expectations because of its supreme carrier mobility and saturation velocity. However, its main disadvantage, the lack of bandgap, has not been satisfactorily solved. As a result, maximum oscillation frequency (fmax) which indicates transistors’ power amplification ability has been disappointing. Here, we present submicron field-effect transistors with specially designed low-resistance gate and excellent source/drain contact, and therefore significantly improved fmax. The fabrication was assisted by the advanced 8-inch CMOS back-end-of-line technology. A 200-nm-gate-length GFET achieves fT/fmax = 35.4/50 GHz. All GFET samples with gate lengths ranging from 200 nm to 400 nm possess fmax 31–41% higher than fT, closely resembling Si n-channel MOSFETs at comparable technology nodes. These results re-strengthen the promise of graphene field-effect transistors in next generation semiconductor electronics.