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George F Reiter, Aniruddha Deb, Yoshiharu Sakurai, Masayoshi Itou, Alexander I Kolesnikov
X-ray Compton scattering measurements of the electron momentum distribution in water confined in both single walled and double walled carbon nanotubes (SWNT and DWNT), as a function of temperature and confinement size, presented here, together with earlier measurements of the proton momentum distribution in the same systems, using neutron Compton scattering, provide a coherent picture of an anomalous state of water that exists because of nano-confinement. This state cannot be described by the weakly interacting molecule picture...
October 17, 2016: Journal of Physical Chemistry Letters
Griet Depotter, Jean-Hubert Olivier, Mary G Glesner, Pravas Deria, Yusong Bai, George Bullard, Amar S Kumbhar, Michael J Therien, Koen Clays
We report the first-order hyperpolarizabilities (βHRS values) of individualized, length-sorted (700 ± 50 nm long) (6,5) SWNTs and corresponding polymer-wrapped (6,5) SWNT superstructures. These SWNT-based nanohybrids feature semiconducting polymers that wrap the SWNT surface in an exclusive left-handed helical fashion. Manipulation of the polymer electronic structures in these well-defined nanoscale objects provides a new avenue to modulate the magnitude of βHRS at long wavelength (1280 nm).
October 6, 2016: Chemical Communications: Chem Comm
Yoko Matsuzawa, Yuko Takada, Hirokuni Jintoku, Hideyuki Kihara, Masaru Yoshida
We describe the application of photodetachable and recyclable dispersants for SWNTs in the fabrication of photo-patterned SWNT thin films. Because the adsorption and desorption of the dispersants on the SWNT surfaces affect not only their dispersibility in water but also their solubility, SWNT photo-patterns were obtained on glass substrates in only three steps, i.e. casting the SWNT/dispersants solution, UV-light exposure of the casted SWNT/dispersants films through a photomask, and subsequent rinsing with neutral water...
October 10, 2016: ACS Applied Materials & Interfaces
Yutaka Maeda, Shun Minami, Yuya Takehana, Jing-Shuang Dang, Shun Aota, Kazunari Matsuda, Yuhei Miyauchi, Michio Yamada, Mitsuaki Suzuki, Rui-Sheng Zhao, Xiang Zhao, Shigeru Nagase
Single-walled carbon nanotubes (SWNTs) were subjected to alkylation using alkyl bromide and alkyl dibromide, and the photoluminescence (PL) properties of the resulting alkylated SWNTs were characterized. Two new PL peaks were observed along with the intrinsic PL peak at 976 nm when alkyl bromide was used (SWNT-Bu: ∼1095 and 1230 nm, SWNT-Bn: 1104 and 1197 nm). In contrast, the use of α,α'-dibromo-o-xylene as an alkyl dibromide primarily resulted in only one new PL peak, which was observed at 1231 nm. The results revealed that the Stokes shift of the new peaks was strongly influenced by the addition patterns of the substituents...
September 29, 2016: Nanoscale
Keigo Otsuka, Taiki Inoue, Yuki Shimomura, Shohei Chiashi, Shigeo Maruyama
We observe field emission between nanogaps and voltage-driven gap extension of single-walled carbon nanotubes (SWNTs) on substrates during the electrical breakdown process. Experimental results show that the gap size is dependent on the applied voltage and humidity, which indicates high controllability of the gap size by appropriate adjustment of these parameters in accordance with the application. We propose a mechanism for the gap formation during electrical breakdown as follows. After small gaps are formed by Joule heating-induced oxidation, SWNTs on the anode side are electrochemically etched due to physically-adsorbed water from the air and the enhanced electric field at the SWNT tips...
September 15, 2016: Nanoscale
Xiaoyuan Liang, Wenting Shang, Chongwei Chi, Chaoting Zeng, Kun Wang, Chihua Fang, Qingshan Chen, Huiyu Liu, Yingfang Fan, Jie Tian
Recently, photothermal therapy (PTT) has become viewed as an ideal auxiliary therapeutic treatment for cancers. However, the development of safe, convenient, and highly effective photothermal agents remains a great challenge. In this study, we prepared single-walled carbon nanotubes (SWNTs) for PTT against breast tumors under the guidance of infrared fluorescent cyanines. Tumors were accurately located using near-infrared imaging (NIR) and then exposed to laser irradiation. Both the in vivo and in vitro results showed that the SWNTs have high stability and low cytotoxicity...
September 30, 2016: Cancer Letters
Chompoonut Rungnim, Thanyada Rungrotmongkol, Rungtiva P Poo-Arporn
In the present study, we describe here the pH condition activating doxorubicin (DOX) anticancer drugs loading and release over single-wall carbon nanotube (SWNT) non-covalently wrapped with chitosan (CS). The possibility of drug displacement on DOX/CS/SWNT nanocarrier was investigated using molecular dynamics simulations. The drug loading and release were monitored via displacement analysis and binding energy calculations. The simulated results clearly showed that the drugs well interacted with the CS/SWNT at physiological pH (pH 7...
September 21, 2016: Journal of Molecular Graphics & Modelling
David R Barbero, Samuel D Stranks
Carbon nanotubes have a variety of remarkable electronic and mechanical properties that, in principle, lend them to promising optoelectronic applications. However, the field has been plagued by heterogeneity in the distributions of synthesized tubes and uncontrolled bundling, both of which have prevented nanotubes from reaching their full potential. Here, a variety of recently demonstrated solution-processing avenues is presented, which may combat these challenges through manipulation of nanoscale structures...
September 16, 2016: Advanced Materials
Vasanth S Murali, Ruhung Wang, Carole A Mikoryak, Paul Pantano, Rockford K Draper
Single-walled carbon nanotubes (SWNTs) are used in the near infrared (NIR)-mediated thermal ablation of tumor cells because they efficiently convert absorbed NIR light into heat. Despite the therapeutic potential of SWNTs, there have been no published studies that directly quantify how many SWNTs need be associated with a cell to achieve a desired efficiency of killing, or what is the most efficient subcellular location of SWNTs for killing cells. Herein we measured dose response curves for the efficiency of killing correlated to the measured amounts of folate-targeted SWNTs that were either on the surface or within the vacuolar compartment of normal rat kidney cells...
October 21, 2016: Nanotechnology
Qi Wang, Chunya Wang, Mingchao Zhang, Muqiang Jian, Yingying Zhang
Silkworm silk is gaining significant attention from both the textile industry and research society because of its outstanding mechanical properties and lustrous appearance. The possibility of creating tougher silks attracts particular research interest. Carbon nanotubes and graphene are widely studied for their use as reinforcement. In this work, we report mechanically enhanced silk directly collected by feeding Bombyx mori larval silkworms with single-walled carbon nanotubes (SWNTs) and graphene. We found that parts of the fed carbon nanomaterials were incorporated into the as-spun silk fibers, whereas the others went into the excrement of silkworms...
October 12, 2016: Nano Letters
Myungsu Jang, Somin Kim, Haneul Jeong, Sang-Yong Ju
Sorted single-walled carbon nanotubes (SWNTs) are of paramount importance for their utilization in high-end optoelectronic applications. Sodium cholate (SC)-based density gradient ultracentrifugation (DGU) has been instrumental in isolating small diameter (d t) SWNTs. Here, we show that SWNTs wrapped by flavin mononucleotide (FMN) as a dispersing agent are sorted in DGU, and show sorting order reversal behavior, departing from prototypical SC-SWNT trends. Larger d t SWNTs are sorted in lower density (ρ), and buoyant ρ distribution of FMN-SWNT ranges from 1...
October 14, 2016: Nanotechnology
Felix F Bergler, Sabine Stahl, Annika Goy, Friedrich Schöppler, Tobias Hertel
The interaction of sodium cholate (NaC) with (6,5) single-wall carbon nanotubes (SWNTs) is investigated using photoluminescence spectroscopy. Dilution of SWNT-NaC suspensions is accompanied by changes in the exciton PL quantum yield and peak emission energy. An abrupt change of the exciton emission peak energy at NaC concentrations between 10 and 14 mM indicates strongly cooperative formation of a micellar phase on (6,5) SWNT surfaces with a Hill coefficient of nH = 65 ± 6. This is in contrast to the formation of free NaC micelles with aggregation numbers of only about 4 and suggests that the cooperativity of NaC micelle formation on nanotube surfaces is strongly substrate-enhanced...
September 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
He Zhao, Yu Chao, Jingjing Liu, Jie Huang, Jian Pan, Wanliang Guo, Jizhi Wu, Mao Sheng, Kai Yang, Jian Wang, Zhuang Liu
Single-walled carbon nanotubes (SWNTs) with various unique properties have attracted great attention in cancer theranostics. Herein, SWNTs are coated with a shell of polydopamine (PDA), which is further modified by polyethylene glycol (PEG). The PDA shell in the obtained SWNT@PDA-PEG could chelate Mn(2+), which together with metallic nanoparticulate impurities anchored on SWNTs offer enhanced both T1 and T2 contrasts under magnetic resonance (MR) imaging. Meanwhile, also utilizing the PDA shell, radionuclide (131)I could be easily labeled onto SWNT@PDA-PEG, enabling nuclear imaging and radioisotope cancer therapy...
2016: Theranostics
Matthew L Moser, Guanghui Li, Mingguang Chen, Elena Bekyarova, Mikhail E Itkis, Robert C Haddon
Optical properties of electrochromic materials can be controlled by the application of an electric field allowing recent development of new applications such as smart windows technology for indoor climate control and energy conservation. We report the fabrication of a single-walled nanotube (SWNT) thin film based electro-optical modulator controlled by ionic liquid polarization in which the active electrochromic layer is made of a film of semiconducting (SC-) SWNTs and the counter-electrode is composed of a film of metallic (MT-) SWNTs...
September 14, 2016: Nano Letters
Darryl Fong, William J Bodnaryk, Nicole A Rice, Sokunthearath Saem, Jose M Moran-Mirabal, Alex Adronov
The separation and isolation of semiconducting and metallic single-walled carbon nanotubes (SWNTs) on a large scale remains a barrier to many commercial applications. Selective extraction of semiconducting SWNTs by wrapping and dispersion with conjugated polymers has been demonstrated to be effective, but the structural parameters of conjugated polymers that dictate selectivity are poorly understood. Here, we report nanotube dispersions with a poly(fluorene-co-pyridine) copolymer and its cationic methylated derivative, and show that electron-deficient conjugated π-systems bias the dispersion selectivity toward metallic SWNTs...
October 4, 2016: Chemistry: a European Journal
Patrick R Unwin, Aleix G Güell, Guohui Zhang
Carbon materials have a long history of use as electrodes in electrochemistry, from (bio)electroanalysis to applications in energy technologies, such as batteries and fuel cells. With the advent of new forms of nanocarbon, particularly, carbon nanotubes and graphene, carbon electrode materials have taken on even greater significance for electrochemical studies, both in their own right and as components and supports in an array of functional composites. With the increasing prominence of carbon nanomaterials in electrochemistry comes a need to critically evaluate the experimental framework from which a microscopic understanding of electrochemical processes is best developed...
September 20, 2016: Accounts of Chemical Research
Mira Jang, Jongtaek Lee, Teahee Park, Junyoung Lee, Jonghee Yang, Whikun Yi
We fabricated the etched Si substrate having the pyramidal pattern size from 0.5 to 4.2 μm by changing the texturing process parameters, i.e., KOH concentration, etching time, and temperature. Single walled carbon nanotubes (SWNTs) were then synthesized on the etched Si substrates with different pyramidal pattern by chemical vapor deposition. We investigated the optical and electronic properties of SWNT film grown on the etched Si substrates of different morphology by using scanning electron microscopy, Raman spectroscopy and conducting probe atomic force microscopy...
March 2016: Journal of Nanoscience and Nanotechnology
Bramhe N Sachin, Hwangbo Seon Ae, Min Cheol Chu
We demonstrate the use of novel type of sonication method, focused sonication, with added advantages over bath and probe type of sonication for the dispersion of single walled carbon nanotubes (SWNT). Di-chloro benzene was used as the solvent for dispersion of SWNT. Results from focused sonication and bath sonication were compared and found that focused sonication results in better dispersion. Also Raman spectroscopy was analysed to ascertain if focused sonication causes any damage to the tubes and it was found that there was no damage to the SWNT...
March 2016: Journal of Nanoscience and Nanotechnology
Alejandro López-Moreno, Belén Nieto-Ortega, Maria Moffa, Alberto de Juan, M Mar Bernal, Juan P Fernández-Blázquez, Juan J Vilatela, Dario Pisignano, Emilio M Pérez
In this work, we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine SWNTs, mechanically interlocked derivatives of SWNTs (MINTs), and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200% were observed for the polystyrene-MINT samples with an optimized loading of just 0.01 wt %, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence...
August 23, 2016: ACS Nano
Ngoc Bui, Eric R Meshot, Sangil Kim, José Peña, Phillip W Gibson, Kuang Jen Wu, Francesco Fornasiero
A flexible membrane with sub-5 nm single-walled carbon nanotube (SWNT) pores is developed by F. Fornasiero and co-workers, as described on page 5871, for application as a key component of protective, yet breathable fabrics. The SWNTs are shown to enable exceptionally fast transport of water vapor under a concentration driving force. Thus, membranes having SWNTs as moisture-conductive pores feature outstanding breathability and provide a high degree of protection from biological threats by size exclusion.
July 2016: Advanced Materials
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