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Linda Grabill, Andreas Riemann
A study of π-π interactions between a (7,7) single-walled carbon nanotube (SWNT) and three different aromatic amino acids (AAA), namely L-Tyrosine (Tyr), L-Tryptophan (Trp), and L-Phenylalanine (Phe) was conducted with a Molecular Mechanics (MM) approach. For each of the amino acids we investigated the behavior of six different conformers. We examined the impact of the so-called edge effects by testing the parameters of the built-in switching function in MM. We found the optimal SWNT length to be approximately 80Å for the size of the molecules in our conformational studies...
January 12, 2018: Journal of Physical Chemistry. A
Yusong Bai, Jean-Hubert Olivier, George Bullard, Chaoren Liu, Michael J Therien
The trion, a three-body charge-exciton bound state, offers unique opportunities to simultaneously manipulate charge, spin, and excitation in one-dimensional single-walled carbon nanotubes (SWNTs) at room temperature. Effective exploitation of trion quasi-particles requires fundamental insight into their creation and decay dynamics. Such knowledge, however, remains elusive for SWNT trion states, due to the electronic and morphological heterogeneity of commonly interrogated SWNT samples, and the fact that transient spectroscopic signals uniquely associated with the trion state have not been identified...
January 8, 2018: Proceedings of the National Academy of Sciences of the United States of America
Mohammadali Sheikholeslam, Scott D Wheeler, Keely G Duke, Mungo Marsden, Mark Pritzker, P Chen
The use of hybrid self-assembling peptide (EFK8)-carbon nanotube (SWNT) hydrogels for tissue engineering and in vitro 3D cancer spheroid formation is reported. These hybrid hydrogels are shown to enhance the attachment, spreading, proliferation and movement of NIH-3T3 cells relative to that observed using EFK8-only hydrogels. After five days, ∼30% more cells are counted when the hydrogel contains SWNTs. Also, 3D encapsulation of these cells when injected in hydrogels does not adversely affect their behavior...
December 14, 2017: Acta Biomaterialia
A Jeantet, Y Chassagneux, T Claude, J S Lauret, C Voisin
At cryogenic temperatures, the photoluminescence (PL) spectrum of nano-emitters may still be significantly broadened due to interactions with the environment. The interplay of spectral diffusion (SD) and phonon broadening in this context is still a debated issue. Singlewall carbon nanotubes (SWNTs) are a particularly relevant system to address this topic as they show intense spectral diffusion and undergo a high exciton-phonon coupling due to their one-dimensional geometry. Here, we investigate the correlations between the spectral diffusion of the main line and that of the wings in SWNTs quantitatively and demonstrate that the photoluminescence spectrum undergoes spectral jumps as a whole, without distortions...
December 15, 2017: Nanoscale
Tyler Guin, Benjamin A Kowalski, Rahul Rao, Anesia D Auguste, Christopher A Grabowski, Pamela Lloyd, Vincent P Tondiglia, Benji Maruyama, Richard A Vaia, Timothy J White
Liquid crystal elastomers (LCE) exhibit distinctive anisotropic mechanical, thermal, and optical properties. The director orientation within an LCE can be spatially localized into voxels (3-dimensional pixels) via photoalignment surfaces. Here, we prepare nanocomposites in which both the orientation of the LCE and single walled carbon nanotube (SWNT) are locally and arbitrarily oriented in discrete volume elements (voxels). The addition of SWNTs increases the stiffness of the LCE in the orientation direction, yielding a material with a 5:1 directional modulus contrast...
December 14, 2017: ACS Applied Materials & Interfaces
Qiang Zhang, Nan Wei, Patrik Laiho, Esko I Kauppinen
Transparent conducting films (TCFs) are critical components of many optoelectronic devices that pervade modern technology. Due to their excellent optoelectronic properties and flexibility, single-walled carbon nanotube (SWNT) films are regarded as an important alternative to doped metal oxides or brittle and expensive ceramic materials. Compared with liquid-phase processing, the dry floating catalyst chemical vapor deposition (FCCVD) method without dispersion of carbon nanotubes (CNTs) in solution is more direct and simpler...
November 27, 2017: Topics in Current Chemistry (Journal)
Shusuke Oura, Masahiro Ito, Yoshikazu Homma, Kazuo Umemura
In this study, we investigated the interaction of base sequence-assigned single-stranded DNA (ssDNA) molecules with the surfaces of single-walled carbon nanotube (SWNT)-thymine (T30)/cytosine (C30) hybrids (T30/C30-SWNT), by measuring the modulation of near-infrared (NIR) photoluminescence (PL). Significant PL shifts were observed when T30/C30-SWNTs were reacted with 30-mers of adenine (A30)/guanine (G30). In contrast, when non-complementary ssDNA was used, no significant energy shift was observed in the PL modulation except when T30-SWNTs were reacted with G30...
November 20, 2017: European Biophysics Journal: EBJ
Xueling Ren, Jing Lin, Xuefang Wang, Xiao Liu, Erjuan Meng, Rui Zhang, Yanxiao Sang, Zhenzhong Zhang
The efficacy of RNA interference (RNAi)-based cancer gene therapy is limited by its unexpected side effects, thus necessitating a strategy to precisely trigger conditional gene knockdown. In this study, we engineered a novel photoactivatable RNAi system, named as polyetherimide-modified single-wall carbon nanotube (PEI-SWNT)/pHSP-shT, that enables optogenetic control of targeted gene suppression in tumor cells. PEI-SWNT/pHSP-shT comprises a stimulus-responsive nanocarrier (PEI-SWNT), and an Hsp70B'-promoter-driven RNAi vector (pHSP-shT)...
2017: International Journal of Nanomedicine
Mohammad Towshif Rabbani, Christoph F Schmidt, Alexandra Ros
Single-walled carbon nanotubes (SWNTs) offer unique electrical and optical properties. Common synthesis processes yield SWNTs with large length polydispersity (several tens of nanometers up to centimeters) and heterogeneous electrical and optical properties. Applications often require suitable selection and purification. Dielectrophoresis is one manipulation method for separating SWNTs based on dielectric properties and geometry. Here, we present a study of surfactant and ssDNA wrapped SWNTs suspended in aqueous solutions manipulated by insulator-based dielectrophoresis (iDEP)...
November 13, 2017: Analytical Chemistry
Xiaokai Li, Marina Mariano, Lyndsey McMillon-Brown, Jing-Shun Huang, Matthew Y Sfeir, Mark A Reed, Yeonwoong Jung, André D Taylor
Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g., preparation of SWNT thin films and SWNT/Si p-n junctions). The flexible SWNT/Si solar cells present an intrinsic efficiency ≈7.5% without any additional light-trapping structures. By using these solar cells as model systems, the charge transport mechanisms at the SWNT/Si interface are investigated using femtosecond transient absorption...
November 10, 2017: Small
Keigo Otsuka, Taiki Inoue, Etsuo Maeda, Reo Kometani, Shohei Chiashi, Shigeo Maruyama
Ballistic transport and sub-10 nm channel lengths have been achieved in transistors containing one single-walled carbon nanotube (SWNT). To fill the gap between single-tube transistors and high-performance logic circuits for the replacement of silicon, large-area, high-density, and purely semiconducting (s-) SWNT arrays are highly desired. Here we demonstrate the fabrication of multiple transistors along a purely semiconducting SWNT array via an on-chip purification method. Water- and polymer-assisted burning from site-controlled nanogaps is developed for the reliable full-length removal of metallic SWNTs with the damage to s-SWNTs minimized even in high-density arrays...
November 13, 2017: ACS Nano
Yu Ishibashi, Masahiro Ito, Yoshikazu Homma, Kazuo Umemura
We measured the optical responses of single-walled carbon nanotubes (SWNTs) after adding Japanese green tea or catechin. SWNTs were covered with DNA in aqueous solution, and tea or catechin solution was added to the DNA-SWNT suspension. The antioxidant effects of tea and catechin were detected as changes in the near-infrared (NIR) absorption (ABS) and NIR-photoluminescence (PL) spectra of the SWNTs. Commercial Japanese tea, diluted 100 times and containing 15μg/mL catechin, was sufficient for recovering NIR-ABS and NIR-PL spectra when the DNA-SWNT suspension was pre-treated with 0...
October 18, 2017: Colloids and Surfaces. B, Biointerfaces
Satoshi Yasuda, Takahiro Yoshii, Shohei Chiashi, Shigeo Maruyama, Kei Murakoshi
Local surface plasmon resonance (LSPR)-induced oxidation of semiconducting and metallic single-walled nanotubes (SWNTs) on the nanometer scale was investigated using surface-enhanced Raman scattering (SERS) measurements. An isolated SWNT was supported on a well-defined Au nanodimer structure that possesses an LSPR field at the nanogap under light irradiation, and highly intense SERS spectra of the SWNT at the gap region were measured. SERS analysis under O2-saturated solutions and the addition of reactive oxygen species inhibitors demonstrated that condensed singlet oxygen ((1)O2), which is one of the reactive oxygen species, was efficiently generated from a semiconducting SWNT at the nanogap by the LSPR field and led to the local oxidation of the tube...
November 8, 2017: ACS Applied Materials & Interfaces
Zhaoyao Zhan, Rongzhou Lin, Van-Thai Tran, Jianing An, Yuefan Wei, Hejun Du, Tuan Tran, Wenqiang Lu
A wearable and flexible pressure sensor is essential to the realization of personalized medicine through continuously monitoring an individual's state of health and also the development of a highly intelligent robot. A flexible, wearable pressure sensor is fabricated based on novel single-wall carbon nanotube /tissue paper through a low-cost and scalable approach. The flexible, wearable sensor showed superior performance with concurrence of several merits, including high sensitivity for a broad pressure range and an ultralow energy consumption level of 10-6 W...
November 1, 2017: ACS Applied Materials & Interfaces
Yuichiro Kunai, Albert Tianxiang Liu, Anton L Cottrill, Volodymyr B Koman, Pingwei Liu, Daichi Kozawa, Xun Gong, Michael S Strano
The concept of electrical energy generation based on asymmetric chemical doping of single-walled carbon nanotube (SWNT) papers is presented. We explore 27 small, organic, electron-acceptor molecules that are shown to tune the output open-circuit voltage (VOC) across three types of pristine SWNT papers with varying (n,m) chirality distributions. A considerable enhancement in the observed VOC, from 80 to 440 mV, is observed for SWNT/molecule acceptor pairs that have molecular volume below 120 Å(3) and lowest unoccupied molecular orbital (LUMO) energies centered around -0...
October 20, 2017: Journal of the American Chemical Society
Juan Yang, Daqi Zhang, Yuecong Hu, Chenmaya Xia, Sida Sun, Yan Li
The chirality (n,m) determines all structures and properties of a single-walled carbon nanotube (SWNT), therefore, accurate and convenient (n,m) assignments are vital in nanotube-related science and technology. Previously, a so-called Kataura plot that protracts the excitonic transition energies (Eii's) of SWNTs with various (n,m) with respect to the tube diameter (dt) has been widely utilized by researchers in the nanotube community for all (n,m)-related studies. However, the facts that both Eii and the calculated dt are subject to interactions with the environments make it inconvenient to accurately determine the (n,m) under complex environments...
October 24, 2017: ACS Nano
Fajun Xiao, Can Liu, Kaihui Liu, Wuyun Shang, Weiren Zhu, Jianlin Zhao
We propose and demonstrate an approach for tailoring the Raman response of an individual single-walled carbon nanotube (SWNT) by employing the optical vortex as the excitation. Specifically, we observe the blueshifts of radial breathing mode and G mode when the topological charge of the vortex beam is increased from 0 to 5. Further theoretical analysis yields that the optical absorption and the corresponding laser heating effect of SWNT are inversely proportional to the topological charge of the optical vortex...
July 1, 2017: Optics Letters
David R Barbero, Nicolas Boulanger
Self-assembled percolated networks play an important role in many advanced electronic materials and devices. In nanocarbon composites, decreasing the percolation threshold ϕc is of paramount importance to reduce nanotube bundling, minimize material resources and costs, and enhance charge transport. Here we demonstrate that three-dimensional nanoconfinement in single-wall carbon nanotube/polymer nanocomposites produces a strong reduction in ϕc, reaching the lowest value ever reported in this system of ϕc ≈ 1...
October 24, 2017: ACS Nano
Guanghui Li, Mohammad Suja, Mingguang Chen, Elena Bekyarova, Robert C Haddon, Jianlin Liu, Mikhail E Itkis
Ultraviolet (UV) photodetectors based on heterojunctions of conventional (Ge, Si, and GaAs) and wide bandgap semiconductors have been recently demonstrated, but achieving high UV sensitivity and visible-blind photodetection still remains a challenge. Here, we utilized a semitransparent film of p-type semiconducting single-walled carbon nanotubes (SC-SWNTs) with an energy gap of 0.68 ± 0.07 eV in combination with a molecular beam epitaxy grown n-ZnO layer to build a vertical p-SC-SWNT/n-ZnO heterojunction-based UV photodetector...
October 5, 2017: ACS Applied Materials & Interfaces
C T Stoppiello, J Biskupek, Z Y Li, G A Rance, A Botos, R M Fogarty, R A Bourne, J Yuan, K R J Lovelock, P Thompson, M W Fay, U Kaiser, T W Chamberlain, A N Khlobystov
The preparation of inorganic nanomaterials with a desired structure and specific properties requires the ability to strictly control their size, shape and composition. A series of chemical reactions with platinum compounds carried out within the 1.5 nm wide channel of single-walled carbon nanotubes (SWNTs) have demonstrated the ability of SWNTs to act as both a very effective reaction vessel and a template for the formation of nanocrystals of platinum di-iodide and platinum di-sulphide, materials that are difficult to synthesise in the form of nanoparticles by traditional synthetic methods...
October 5, 2017: Nanoscale
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