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Nathaniel E Kallmyer, Joseph Musielwicz, Joel Sutter, Nigel Forest Reuel
Hydrolytic enzymes are a topic of continual study and improvement due to their industrial impact and biological implications; however, the ability to measure the activity of these enzymes, especially in high-throughput assays, is limited to an established, few enzymes and often involves the measurement of secondary byproducts or the design of a complex degradation probe. Herein, a versatile single-walled carbon nanotube (SWNT)-based biosensor that is straightforward to produce and measure is described. The hydrolytic enzyme substrate is rendered as an amphiphilic polymer which is then used to solubilize the hydrophobic nanotubes...
March 20, 2018: Analytical Chemistry
Yo Han Kwon, Krysten Minnici, Jung Jin Park, Sujin R Lee, Guoyan Zhang, Esther S Takeuchi, Kenneth J Takeuchi, Amy C Marschilok, Elsa Reichmanis
Conjugated polymers possessing polar functionalities were shown to effectively anchor single-walled carbon nanotubes (SWNTs) to the surface of high-capacity anode materials, and enable the formation of electrical networks. Specifically, poly[3-(potassium-4-butanoate) thiophene] (PPBT) served as a bridge between SWNT networks and various anode materials, including monodispersed Fe3O4 spheres (sFe3O4), and silicon nanoparticles (Si NPs). The PPBT π‒conjugated backbone and carboxylate (COO‒) substituted alkyl side chains, respectively, attracted the SWNT π‒electron surface and chemically interacted with active material surface hydroxyl (‒OH) species to form a carboxylate bond...
March 10, 2018: Journal of the American Chemical Society
Darya Alizadeh, Ethan E White, Teresa C Sanchez, Shunan Liu, Leying Zhang, Behnam Badie, Jacob M Berlin
Even when treated with aggressive current therapies, patients with glioblastoma usually survive less than two years and exhibit a high rate of recurrence. CpG is an oligonucleotide that activates the innate immune system via TLR9 activation. Injection of CpG into glioblastoma tumors showed promise as an immunotherapy in mouse models but proved disappointing in human trials. One aspect of glioma that is not addressed by CpG therapy alone is the highly invasive nature of glioma cells, which is associated with resistance to radiation and chemotherapy...
March 10, 2018: Bioconjugate Chemistry
Felix J Berger, Thomas M Higgins, Marcel Rother, Arko Graf, Yuriy Zakharko, Sybille Allard, Maik Matthiesen, Jan M Gotthardt, Ullrich Scherf, Jana Zaumseil
Dense layers of semiconducting single-walled carbon nanotubes (SWNTs) serve as electrochromic materials in the near-infrared with high optical density and high conductivity. Electrochromic cells with tunable notch filter properties instead of broadband absorption are created via highly selective dispersion of specific semiconducting SWNTs through polymer-wrapping followed by deposition of thick films by aerosol-jet printing. A simple planar geometry with spray-coated mixed SWNTs as the counter electrode renders transparent metal oxides redundant and facilitates complete bleaching within a few seconds through iongel electrolytes with high ionic conductivities...
March 9, 2018: ACS Applied Materials & Interfaces
Tongfang Xiao, Yanan Jiang, Wenliang Ji, Lanqun Mao
The unique electronic and chemical structures of carbon nanotubes (CNTs) have well enabled their applications in electrochemistry and electroanalytical chemistry, however, the difficulty in reproducibly confining CNTs onto substrate electrode, particularly onto microelectrodes, still remains to be addressed. In this study, we develop a method to reproducibly confine single-walled carbon nanotubes (SWNTs) onto carbon fiber microelectrodes (CFEs) with electrophoretic deposition (EPD) for in vivo measurement of ascorbate...
March 8, 2018: Analytical Chemistry
Siyu Liu, Jian Zhang, Jean Pierre Nshimiyimana, Xiannian Chi, Xiao Hu, Pei Wu, Jia Liu, Gongtang Wang, Lianfeng Sun
In this work, we report an effective technique of fabricating ultraclean individual suspended single-walled carbon nanotube (SWNT) transistors. The surface tension of molten silver is utilized to suspend an individual SWNT between a pair of Pd electrodes during annealing treatment. This approach avoids the usage and the residues of organic resist attached to SWNTs, resulting ultraclean SWNT devices. And the resistance per micrometer of suspended SWNTs is found to be smaller than that of non-suspended SWNTs, indicating the effect of the substrate on the electrical properties of SWNTs...
February 14, 2018: Nanotechnology
David G Calatayud, Haobo Ge, Navaratnarajah Kuganathan, Vincenzo Mirabello, Robert M J Jacobs, Nicholas H Rees, Craig T Stoppiello, Andrei N Khlobystov, Rex M Tyrrell, Enrico Da Como, Sofia I Pascu
The encapsulation of CdSe nanocrystals within single-walled carbon nanotube (SWNT) cavities of varying dimensions at elevated temperatures under strictly air-tight conditions is described for the first time. The structures of CdSe nanocrystals under confinement inside SWNTs was established in a comprehensive study, combining both experimental and DFT theoretical investigations. The calculated binding energies show that all considered polymorphs [(3:3), (4:4), and (4:2)] may be obtained experimentally. The most thermodynamically stable structure (3:3) is directly compared to the experimentally observed CdSe structures inside carbon nanotubes...
February 2018: ChemistryOpen
Dewu Lin, Shuchen Zhang, Zhe Zheng, Wenping Hu, Jin Zhang
Direct growth of chirality-controlled single-walled carbon nanotubes (SWNTs) with metal catalyst free strategy, like cloning or epitaxial growth, has suffered from the low efficiency. The underlying problem is the activation of seed edge. Here an unexpectedly efficient microwave-assisted pathway to regenerate SWNTs from carbon fragments on SiO2 /Si substrate is demonstrated via Raman spectroscopy and atomic force microscope (AFM) characterization. In this attempt, microwave irradiation provides fast heating to remove polar groups bonded to carbon nanotubes and reduce the spontaneous closure of tubes' open ends...
February 12, 2018: Small
Il Jeon, Yutaka Matsuo, Shigeo Maruyama
Photovoltaics, more generally known as solar cells, are made from semiconducting materials that convert light into electricity. Solar cells have received much attention in recent years due to their promise as clean and efficient light-harvesting devices. Single-walled carbon nanotubes (SWNTs) could play a crucial role in these devices and have been the subject of much research, which continues to this day. SWNTs are known to outperform multi-walled carbon nanotubes (MWNTs) at low densities, because of the difference in their optical transmittance for the same current density, which is the most important parameter in comparing SWNTs and MWNTs...
January 22, 2018: Topics in Current Chemistry (Journal)
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 single-stranded DNA-wrapped SWNTs suspended in aqueous solutions manipulated by insulator-based dielectrophoresis (iDEP)...
December 19, 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 28, 2017: ACS Nano
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