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ACS Nano

Amin Morteza Najarian, Richard L McCreery
Carbon-based molecular junctions consisting of aromatic oligomers between conducting sp(2) hybridized carbon electrodes exhibit structure dependent current densities (J) when the molecular layer thickness (d) exceeds ~5 nm. All four of the molecular structures examined exhibit an unusual, nonlinear ln J vs bias voltage (V) dependence which is not expected for conventional coherent tunneling or activated hopping mechanisms. All molecules exhibit a weak temperature dependence, with J increasing typically a factor of two over the range of 200-440 K...
February 27, 2017: ACS Nano
Hao Dong, Ling-Dong Sun, Wei Feng, Yuyang Gu, Fuyou Li, Chun-Hua Yan
Optical encoding together with color multiplexing benefits on-site detection, and enriching the components with narrow emissions from lanthanide could greatly increase the coding density. Here, we show the typical example to combine emission color and lifetime which are simultaneously integrated in a single lanthanide nanoparticle. With the multi-compartment core/shell structure, the nanoparticles can activate different emitting pathways under varied excitation. This enables the nanoparticles to generate versatile excitation orthogonalized upconversion luminescence in both emission colors and lifetimes...
February 26, 2017: ACS Nano
Lukáš Ondič, Marian Varga, Karel Hruska, Jan Fait, Peter Kapusta
Silicon vacancy (SiV) centers are optically active defects in diamond. The SiV centers, in contrast to nitrogen vacancy (NV) centers, possess narrow and efficient luminescence spectrum (centered at ≈738 nm) even at room temperature, which can be utilized for quantum photonics and sensing applications. However, most of light generated in diamond is trapped in the material due to the phenomenon of total internal reflection. In order to overcome this issue, we have prepared two-dimensional photonic crystal slabs from polycrystalline diamond thin layers with high density of SiV centers employing bottom-up growth on quartz templates...
February 26, 2017: ACS Nano
Janay Elise Kong, Qingshan Wei, Derek Tseng, Jingzi Zhang, Eric Pan, Michael Lewinski, Omai Brandt Garner, Aydogan Ozcan, Dino Di Carlo
Key challenges with point-of-care (POC) nucleic acid tests include achieving a low cost, portable form factor, and stable readout, while also retaining the same robust standards of benchtop lab-based tests. We addressed two crucial aspects of this problem, identifying a chemical additive, hydroxynapthol blue (HNB), that both stabilizes and significantly enhances intercalator-based fluorescence readout of nucleic acid concentration, and developing a cost-effective fiber optic bundle-based fluorescence microplate reader integrated onto a mobile phone...
February 24, 2017: ACS Nano
Giulia E Pacchioni, Marina Pivetta, Luca Gragnaniello, Fabio Donati, Gabriel Autes, Oleg V Yazyev, Stefano Rusponi, Harald Brune
Iron atoms adsorbed on a Cu(111) surface and buried under polyphenyl-dicarbonitrile molecules exhibit strongly spatial anisotropic Kondo features with directionally dependent Kondo temperatures and line shapes, as evidenced by scanning tunneling spectroscopy. First-principles calculations find nearly full polarization for the half-filled Fe 3dxz and 3dyz orbitals, which therefore can give rise to Kondo screening with the experimentally observed directional dependence, and distinct Kondo temperatures. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements confirm that the spin in both channels is effectively Kondo-screened...
February 24, 2017: ACS Nano
Margarita Vázquez-González, Wei-Ching Liao, Rémi Cazelles, Shan Wang, Xu Yu, Vitaly Gutkin, Itamar Willner
Cu(2+)-functionalized carbon nitride nanoparticles (Cu(2+)‒g-C3N4 NPs), ca. 200 nm, an Cu(2+)-carbon dots (Cu(2+)‒C-dots), ca. 8 nm, act as horseradish peroxidase mimicking catalyst. The nanoparticles catalyze the generation of chemiluminescence in the presence of luminol/H2O2 and catalyze the oxidation of dopamine by H2O2 to form aminochrome. The Cu(2+)‒g-C3N4 driven generation of chemiluminescence is used to develop a H2O2 sensor, and is implemented to develop a glucose detection platform and a sensor for probing glucose oxidase...
February 24, 2017: ACS Nano
Linhan Lin, Xiaolei Peng, Xiaoling Wei, Zhangming Mao, Chong Xie, Yuebing Zheng
Optical manipulation of biological cells and nanoparticles is significantly important in life sciences, early disease diagnosis, and nanomanufacturing. However, low-power and versatile all-optical manipulation has remained elusive. Herein, we have achieved light-directed versatile thermophoretic manipulation of biological cells at an optical power 100~1000 times lower than optical tweezers. By harnessing the permittivity gradient in the electric double layer of the charged surface of the cell membrane, we succeed at the low-power trapping of suspended biological cells within a light-controlled temperature gradient field...
February 23, 2017: ACS Nano
Yooun Heo, Songbai Hu, Pankaj Sharma, Kwang Eun Kim, Byung-Kweon Jang, Claudio Cazorla, Chan-Ho Yang, Jan Seidel
In this study, we report the effect of doping in morphotropic BiFeO3 (BFO) thin films on mechanical properties, revealing variations in the elasticity across the competing phases and their boundaries. Spectroscopic force-distance (F-D) curves and force mapping images by AFM are used to characterize the structure and elastic properties of three BFO thin film materials (pure-BFO, Ca-doped BFO, La-doped BFO). We show that softening behaviour is observed in isovalent La-doped BFO, whereas hardening is seen in aliovalent Ca-doped BFO...
February 22, 2017: ACS Nano
Kian Fan Chung, Joanna Seiffert, Shu Chen, Ioannis G Theodorou, Angela Erin Goode, Bey Fen Leo, Catriona M McGilvery, Farhana Hussain, Coen Wiegman, Christos Rossios, Jie Zhu, Jicheng Gong, Farid Tariq, Vladimir Yufit, Alexander J Monteith, Teruo Hashimoto, Jeremy N Skepper, Mary P Ryan, Junfeng Jim Zhang, Teresa D Tetley, Alexandra E Porter
There is a potential for silver nanowires (AgNWs) to be inhaled but there is little information on their health effects and their chemical transformation inside the lungs in vivo. We studied the effects of short (S-AgNWs; 1.5µm) and long (L-AgNWs; 10 µm) nanowires instilled into the lungs of Sprague-Dawley rats. S- and L-AgNWs were phagocytosed and degraded by macrophages; there was no frustrated phagocytosis. Interestingly, both AgNWs were internalized in alveolar Type II epithelial cells (ATII), with precipitation of Ag2S on their surface as secondary Ag2S nanoparticles...
February 21, 2017: ACS Nano
Lan Nguyen, Hannu-Pekka Komsa, Ekaterina Khestanova, Reza J Kashtiban, Jonathan J P Peters, Sean Lawlor, Ana M Sanchez, Jeremy Sloan, Roman Vladislavovich Gorbachev, Irina V Grigorieva, Arkady V Krasheninnikov, Sarah J Haigh
We have investigated the structure of atomic defects within monolayer NbSe2 encapsulated in graphene by combining atomic-resolution transmission electron microscope (TEM) imaging, density functional theory (DFT) calculations and strain mapping using geometric phase analysis (GPA). We demonstrate the presence of stable Nb and Se monovacancies in monolayer material and reveal that Se monovacancies are the most frequently observed defect, consistent with DFT calculations of their formation energy. We reveal that the presence of adventitious impurities in the surroundings stabilises significant quantities of impurity substituted Se divacancies in the lattice...
February 14, 2017: ACS Nano
Loredana Protesescu, Sergii Yakunin, Sudhir Kumar, Janine Bär, Federica Bertolotti, Norberto Masciocchi, Antonietta Guagliardi, Matthias Grotevent, Ivan Shorubalko, Maryna I Bodnarchuk, Chih-Jen Shih, Maksym V Kovalenko
Colloidal nanocrystals (NCs) of APbX3-type lead halide perovskites [A=Cs+, CH3NH3+ (methylammonium or MA+) or CH(NH2)2+ (formamidinium or FA+); X=Cl-, Br-, I-] have recently emerged as highly versatile photonic sources for applications ranging from simple photoluminescence down-conversion (e.g., for display backlighting) to light emitting diodes. From the perspective of spectral coverage, a formidable challenge facing the use of these materials is how to obtain stable emissions in the red and infrared spectral regions covered by the iodide-based compositions...
February 23, 2017: ACS Nano
Yiran Zheng, Li Tang, Llian Mabardi, Sudha Kumari, Darrell J Irvine
Adoptive cell therapy (ACT) has achieved striking efficacy in B-cell leukemias, but less success treating other cancers, in part due to the rapid loss of ACT T-cell effector function in vivo due to immunosuppression in solid tumors. Transforming growth factor-β (TGF-β) signaling is an important mechanism of immune suppression in the tumor microenvironment, but systemic inhibition of TGF-β is toxic. Here we evaluated the potential of targeting a small molecule inhibitor of TGF-β to ACT T-cells using PEGylated immunoliposomes...
February 23, 2017: ACS Nano
Youngsin Park, Yooseok Kim, Chang Woo Myung, Robert Anthony Taylor, Christopher C S Chan, Benjamin P L Reid, Tim J Puchtler, Robin J Nicholas, Laishram Tomba Singh, Geunsik Lee, Chan-Cuk Hwang, Chong-Yun Park, Kwang S Kim
Despite having outstanding electrical properties, graphene is unsuitable for optical devices because of its zero band gap. Here, we report two-dimensional excitonic photoluminescence (PL) from graphene grown on a Cu(111) surface, which shows an unexpected and remarkably sharp strong emission near 3.16 eV (full-width at half-maximum ≤ 3meV) and multiple emissions around 3.18 eV. As temperature increases, these emissions blue-shift, displaying the characteristic negative thermal coefficient of graphene. The observed PL originates from the significantly suppressed dispersion of excited electrons in graphene caused by hybridization of graphene π and Cu d orbitals of the 1st and 2nd Cu layers at a shifted saddle point 0...
February 23, 2017: ACS Nano
Lichao Sun, Qingfeng Zhang, Guangfang Grace Li, Esteban Villarreal, Xiaoqi Fu, Hui Wang
Kinetically controlled, seed-mediated coreduction provides a robust and versatile synthetic approach to multimetallic nanoparticles with precisely controlled geometries and compositions. Here we demonstrate that single-crystalline cylindrical Au nanorods selectively transform into a series of structurally distinct Au@Au-Pd alloy core-shell bimetallic nanorods with exotic multifaceted geometries enclosed by specific types of facets upon seed-mediated Au-Pd coreduction under diffusion controlled conditions. By adjusting several key synthetic parameters, such as the Pd/Au precursor ratio, the reducing agent concentration, the capping surfactant concentration, and foreign metal ion additives, we have been able to simultaneously fine-tailor the atomic-level surface structures and fine-tune the compositional stoichiometries of the multifaceted Au-Pd bimetallic nanorods...
February 23, 2017: ACS Nano
Chi-Shiang Ke, Chia-Chia Fang, Jia-Ying Yan, Po-Jung Tseng, Joseph R Pyle, Chuan-Pin Chen, Shu-Yi Lin, Jixin Chen, Xuanjun Zhang, Yang-Hsiang Chan
This article describes the design and synthesis of donor-bridge-acceptor-based semiconducting polymer dots (Pdots) that exhibit narrow-band emissions, ultrahigh brightness, and large Stokes shifts in the near-infrared (NIR) region. We systematically investigated the effect of π-bridges on the fluorescence quantum yields of the donor-bridge-acceptor-based Pdots. The Pdots could be excited by a 488 or 532 nm laser and have a high fluorescence quantum yield of 33% with a Stokes shift of more than 200 nm. The emission full width at half-maximum of the Pdots can be as narrow as 29 nm, about 2...
February 23, 2017: ACS Nano
Jian Wang, Ruochen Fang, Jue Hou, Huacheng Zhang, Ye Tian, Huanting Wang, Lei Jiang
Many biological ion channels controlled by biochemical reactions have autonomous and periodic gating functions, which play important roles in continuous mass transport and signal transmission of living systems. Inspired by these functional biological ion channel systems, here we report an artificial self-oscillating nanochannel system that can autonomously and periodically control its gating process under constant conditions. The system is constructed by integrating a chemical oscillator, consisting of BrO3-, Fe(CN)64-, H+, and SO32-, into a synthetic proton-sensitive nanochannel modified with C-quadruplex (C4) DNA motors...
February 22, 2017: ACS Nano
Rubul Mout, Gulen Yesilbag Tonga, Li-Sheng Wang, Moumita Ray, Trinava Roy, Vincent M Rotello
Hierarchical organization of macromolecules through self-assembly is a prominent feature in biological systems. Synthetic fabrication of such structures provides materials with emergent functions. Here we report the fabrication of self-assembled superstructures through co-engineering of recombinant proteins and nanoparticles. These structures feature a highly-sophisticated level of multi-layered hierarchical organization of the components: individual proteins and nanoparticles co-assemble to form discrete assemblies that collapse to form granules, which then further self-organize to generate superstructures of hundreds of nanometer size...
February 22, 2017: ACS Nano
Mattias Borg, Heinz Schmid, Johannes Gooth, Marta D Rossell, Davide Cutaia, Moritz Knoedler, Nicolas Bologna, Stephan Wirths, Kirsten E Moselund, Heike Riel
GaSb nanostructures integrated on Si substrates are of high interest for p-type transistors and mid-IR photodetectors. Here, we investigate the MOCVD growth and properties of GaSb nanostructures monolithically integrated onto silicon-on-insulator wafers using template-assisted selective epitaxy. A high degree of morphological control allows for GaSb nanostructures with critical dimensions down to 20 nm. Detailed investigation of growth parameters reveals that the GaSb growth rate is governed by the desorption processes of an Sb surface, and in turn is insensitive to changes in material transport efficiency...
February 22, 2017: ACS Nano
Jinglei Chen, Guanyong Wang, Yanan Tang, Hao Tian, Jinpeng Xu, Xianqi Dai, Hu Xu, Jinfeng Jia, Wingkin Ho, Maohai Xie
Monolayer (ML) transition-metal dichalcogenides exist in different phases, such as hexagonal (2H) and monoclinic (1T') structures. They show very different properties: semiconducting for 2H-MoTe2 and semi-metallic for 1T'-MoTe2. The formation energy difference between 2H and 1T' phase MoTe2 is small, so there is a high chance to tune the structures of MoTe2 and thereby to bring in applications of phase-change electronics. In this paper, we report growth of both 2H- and 1T'-MoTe2 ML by molecular-beam epitaxy (MBE) and demonstrate its tenability by changing the conditions of MBE...
February 22, 2017: ACS Nano
Grant J Stec, Adam Lauchner, Yao Cui, Peter Nordlander, Naomi J Halas
Polycyclic aromatic hydrocarbon (PAH) molecules, the hydrogen-terminated, subnanometer scale version of graphene, support plasmon resonances with the addition or removal of a single electron. Typically colorless when neutral, they are transformed into vivid optical absorbers in either their positively or negatively charged states. Here we demonstrate a low-voltage, multistate electrochromic device based on PAH plasmon resonances that can be reversibly switched between nearly colorless (0 V), olive (+4 V), and royal blue (-3...
February 22, 2017: ACS Nano
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