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Matthew R Jones, Kevin L Kohlstedt, Matthew N O'Brien, Jinsong Wu, George C Schatz, Chad A Mirkin
The physical properties of matter rely fundamentally on the symmetry of constituent building blocks. This is particularly true for structures that interact with light via the collective motion of their conduction electrons (i.e., plasmonic materials), where the observation of exotic optical effects, such as negative refraction and electromagnetically induced transparency, require the coupling of modes that are only present in systems with nontrivial broken symmetries. Lithography has been the predominant fabrication technique for constructing plasmonic metamaterials, as it can be used to form patterns of arbitrary complexity, including those with broken symmetry...
August 18, 2017: Nano Letters
Carmen M González-Henríquez, Vanessa A Villegas-Opazo, Dallits H Sagredo-Oyarce, Mauricio A Sarabia-Vallejos, Claudio A Terraza
Biomimetic planar artificial membranes have been widely studied due to their multiple applications in several research fields. Their humectation and thermal response are crucial for reaching stability; these characteristics are related to the molecular organization inside the bilayer, which is affected by the aliphatic chain length, saturations, and molecule polarity, among others. Bilayer stability becomes a fundamental factor when technological devices are developed-like biosensors-based on those systems...
August 18, 2017: Biosensors
Hyungseok Kang, Yeon Tae Kim, Siuk Cheon, Gi-Ra Yi, Jeong Ho Cho
We developed a method of chemically welding silver nanowires (AgNWs) using an aqueous solution containing sodium halide salts (NaF, NaCl, NaBr, or NaI). The halide welding was performed simply by immersing the as-coated AgNW film into the sodium halide solution, and the resulting material was compared with that obtained using two typical thermal and plasmonic welding techniques. The halide welding dramatically reduced the sheet resistance of the AgNW electrode due to the strong fusion among nanowires at each junction while preserving the optical transmittance...
August 18, 2017: ACS Applied Materials & Interfaces
Binbin Zhou, Shaofei Li, Xianghu Tang, Pan Li, Xiaomin Cao, Borong Yu, Liangbao Yang, Jinhuai Liu
Intramolecular proton transfer of hypoxanthine, induced by application of a laser on the surface of a bare noble nanomaterial, was monitored in real time using surface-enhanced Raman spectroscopy (SERS). This monitoring demonstrated the dependence of the reaction on the identity of the nanomaterial and on the laser power density. The results pave the way for monitoring the proton transfer reaction in various relevant fields. In addition, we observed the presence of the proton transfer phenomenon of hypoxanthine in serum, providing a way to avoid the effect of proton transfer and hence achieve more reliable spectra of sera for clinical diagnosis...
August 18, 2017: Nanoscale
Mariano D Susman, Yishai Feldman, Tatyana A Bendikov, Alexander Vaskevich, Israel Rubinstein
Oxidation and corrosion reactions have a major effect on the application of non-noble metals. Kinetic information and simple theoretical models are often insufficient for describing such processes in metals at the nanoscale, particularly in cases involving formation of internal voids (nano Kirkendall effect, NKE) during oxidation. Here we study the kinetics of solid-state oxidation of chemically-grown copper nanoparticles (NPs) by in situ localized surface plasmon resonance (LSPR) spectroscopy during isothermal annealing in the range 110-170 °C...
August 18, 2017: Nanoscale
Mariia V Pavliuk, Arthur B Fernandes, Mohamed Abdellah, Daniel L A Fernandes, Caroline O Machado, Igor Rocha, Yocefu Hattori, Cristina Paun, Erick L Bastos, Jacinto Sá
The efficient conversion of light energy into chemical energy is key for sustainable human development. Several photocatalytic systems based on photovoltaic electrolysis have been used to produce hydrogen via water reduction. However, in such devices, light harvesting and proton reduction are carried separately, showing quantum efficiency of about 10-12%. Here, we report a nano-hybrid photocatalytic assembly that enables concomitant reductive hydrogen production and pollutant oxidation with solar-to-fuel efficiencies up to 20%...
August 17, 2017: Scientific Reports
Yang Liu, Paolo Maccarini, Gregory M Palmer, Wiguins Etienne, Yulin Zhao, Chen-Ting Lee, Xiumei Ma, Brant A Inman, Tuan Vo-Dinh
Metastatic spread is the mechanism in more than 90 percent of cancer deaths and current therapeutic options, such as systemic chemotherapy, are often ineffective. Here we provide a proof of principle for a novel two-pronged modality referred to as Synergistic Immuno Photothermal Nanotherapy (SYMPHONY) having the potential to safely eradicate both primary tumors and distant metastatic foci. Using a combination of immune-checkpoint inhibition and plasmonic gold nanostar (GNS)-mediated photothermal therapy, we were able to achieve complete eradication of primary treated tumors and distant untreated tumors in some mice implanted with the MB49 bladder cancer cells...
August 17, 2017: Scientific Reports
Panagiotis K Chrysanthopoulos, Prashant Mujumdar, Lucy A Woods, Olan Dolezal, Bin Ren, Thomas S Peat, Sally-Ann Poulsen
The discovery of a new zinc binding chemotype from screening a non-biased fragment library is reported. Using the orthogonal fragment screening methods of native state mass spectrometry and surface plasmon resonance a 3-unsubstituted-2,4-oxazolidinedione fragment was found to have low micromolar binding affinity to the zinc metalloenzyme carbonic anhydrase II (CA II). This affinity approached that of fragment sized primary benzene sulfonamides, the classical zinc binding group found in most CA II inhibitors...
August 17, 2017: Journal of Medicinal Chemistry
Aftab Ahmed, Matthew Pelton, Jeffrey R Guest
Measurements of acoustic vibrations in nanoparticles provide a unique opportunity to study mechanical phenomena at nanometer length scales and picosecond time scales. Vibrations in noble-metal nanoparticles have attracted particular attention, because they couple to plasmon resonances in the nanoparticles, leading to strong modulation of optical absorption and scattering. There are three mechanisms that transduce the mechanical oscillations into changes in the plasmon resonance: (1) changes in the nanoparticle geometry, (2) changes in electron density due to changes in the nanoparticle volume, and (3) changes in the interband transition energies due to compression / expansion of the nanoparticle (deformation potential)...
August 17, 2017: ACS Nano
Gaoxing Su, Huaqiao Jiang, Hongyan Zhu, Jing-Jing Lv, Guohai Yang, Bing Yan, Jun-Jie Zhu
Plasmonic Au-Pd nanostructures have drawn significant attention for use in heterogeneous catalysis. In this study, palladium nanodendrite-tipped gold nanorods (PdND-T-AuNRs) were subjected to a facile fabrication under mild reaction conditions. The palladium amounts on the two tips were tunable. In the preparation of PdND-T-AuNRs, dense capped AuNRs, a low reaction temperature, and suitable stabilizing agents were identified as critical reaction parameters for controlling palladium nanodendrites deposited on both ends of AuNRs...
August 17, 2017: Nanoscale
E Tiguntseva, A Chebykin, A Ishteev, R Haroldson, B Balachandran, E Ushakova, F Komissarenko, H Wang, V Milichko, A Tsypkin, D Zuev, W Hu, S Makarov, A Zakhidov
Recently, hybrid halide perovskites have emerged as one of the most promising types of materials for thin-film photovoltaic and light-emitting devices because of their low-cost and potential for high efficiency. Further boosting their performance without detrimentally increasing the complexity of the architecture is critically important for commercialization. Despite a number of plasmonic nanoparticle based designs having been proposed for solar cell improvement, inherent optical losses of the nanoparticles reduce photoluminescence from perovskites...
August 17, 2017: Nanoscale
Antonio A García, Lina S Franco, Miguel A Pirez-Gomez, José L Pech-Pacheco, Jorge F Mendez-Galvan, Carlos Machain-Williams, Lourdes Talavera-Aguilar, José H Espinosa-Carrillo, Miriam M Duarte-Villaseñor, Christian Be-Ortiz, Luz E Espinosa-de Los Monteros, Ariel Castillo-Pacheco, Julian E Garcina-Rejon
Antibody detection and accurate diagnosis of tropical diseases is essential to help prevent the spread of disease. However, most detection methods lack cost-effectiveness and field portability, which are essential features for achieving diagnosis in a timely manner. To address this, 3D-printed oblate spheroid sample chambers were fabricated to measure green light scattering of gold nanoparticles using an optical caustic focus to detect antibodies. Scattering signals of 20-200 nm gold nanoparticles using a green laser were compared to green light emitting diode (LED) light source signals and to Mie theory...
August 17, 2017: Diagnostics
Zahra Torbatian, Reza Asgari
We explore the collective electronic excitations of bilayer molybdenum disulfide (MoS2 ) using the density functional theory together with the random phase approximation. The many-body dielectric function and electron energy-loss spectra are calculated using an ab initio based model involving material-realistic physical properties. The electron energy-loss function of bilayer MoS2 system is found to be sensitive to either electron or hole doping and it is owing to the fact that the Kohn-Sham band dispersions are not symmetric for energies above and below the zero Fermi level...
August 17, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Zhen Guo, Lianqun Zhou, Yuguo Tang, Lin Li, Zhiqi Zhang, Hongbo Yang, Hanbin Ma, Arokia Nathan, Dongxu Zhao
Surface/interface charge carrier generation, diffusion and recombination/transport modulation are especially important in the construction of photodetectors with high-efficiency in the field of nanoscience. In the paper, a kind of ultraviolet (UV) detector is designed based on ZnO nanostructures considering photon-trapping, surface plasmonic resonance (SPR), piezophototronic effect, interface carrier trapping/transport control and collection. Through carefully optimized surface/interface carrier transport modulation, the designed device with detectivity as high as of 1...
August 17, 2017: ACS Applied Materials & Interfaces
Maroua Ben Haddada, David Hu, Michèle Salmain, Lu Zhang, Chen Peng, Yi Wang, Bo Liedberg, Souhir Boujday
We describe the engineering of stable gold nanoparticle (AuNP) bioconjugates for the detection of staphylococcal enterotoxin A (SEA) using localized surface plasmon resonance (LSPR). Two types of AuNP bioconjugates were prepared by covalently attaching anti-SEA antibody (Ab) or SEA to AuNPs. This was achieved by reacting Traut's reagent with lysine residues of both proteins to generate thiol groups that bind to gold atoms on the AuNP surface. These bioconjugates were characterized in-depth by absorption spectroscopy, cryo-transmission electron microscopy, dynamic light scattering, and zeta potential measurements...
August 16, 2017: Analytical and Bioanalytical Chemistry
Sergey S Kharintsev, Anton Kharitonov, Semion Saikin, Alexander M Alekseev, Sergei G Kazarian
We consider a nonlinear mechanism of localized light inelastic scattering within nano-patterned plasmonic and Raman-active titanium nitride (TiN) thin films exposed to continuous-wave (cw) modest-power laser light. Owing to the strong third-order nonlinear interaction between optically excited broadband surface plasmons and localized Stokes and anti-Stokes waves, both stimulated and inverse Raman effects can be observed. We provide experimental evidences for coherent amplification of the localized Raman signals using a planar square shaped refractory antenna...
August 16, 2017: Nano Letters
Zhuangqiang Gao, Haihang Ye, Dianyong Tang, Jing Tao, Sanaz Habibi, Adrienne Minerick, Dianping Tang, Xiaohu Xia
Au nanoparticles (AuNPs) as signal reporters have been utilized in colorimetric in vitro diagnostics (IVDs) for decades. Nevertheless, it remains a grand challenge to substantially enhance the detection sensitivity of AuNP-based IVDs as confined by the inherent plasmonics of AuNPs. In this work, we circumvent this confinement by developing unique dual-functional AuNPs that were engineered by coating conventional AuNPs with ultrathin Pt skins of sub-10 atomic layers (i.e., Au@Pt NPs). The Au@Pt NPs retain the plasmonic activity of initial AuNPs while possessing ultrahigh catalytic activity enabled by Pt skins...
August 18, 2017: Nano Letters
Yun Lu, Feng Qiao, Yue Li, Xiao-Hong Sang, Cong-Ran Li, Jian-Dong Jiang, Xin-Yi Yang, Xue-Fu You
Ferredoxins are iron-sulfur protein that mediate electron transfer in cytochrome P450 mono-oxygenase (CYP)-related catalytic reactions in a wide variety of organisms. Rv1786 is a putative ferredoxin, encoded by a gene located downstream of the gene encoding CYP143A1 in the Mycobacterium tuberculosis genome. However, the structure and function of Rv1786 have remained unclear. Here, the recombinant Mtb Rv1786 was expressed, purified as a His-tagged form and characterized with [3Fe-4S] clusters as its cofactors using a series of measurements including SDS-PAGE, western blot, UV/Visible, MALDI-TOF/TOF-MS, and electron paramagnetic resonance spectroscopic analysis...
August 15, 2017: Applied Microbiology and Biotechnology
Somayeh Jafarinejad, Mahmoud Ghazi-Khansari, Forough Ghasemi, Pezhman Sasanpour, M Reza Hormozi-Nezhad
Catecholamine neurotransmitters, generally including dopamine (DA), epinephrine (EP) and norepinephrine (NE) are known as substantial indicators of various neurological diseases. Simultaneous detection of these compounds and their metabolites is highly recommended in early clinical diagnosis. To this aim, in the present contribution, a high performance colorimetric sensor array has been proposed for the detection and discrimination of catecholamines based on their reducing ability to deposit silver on the surface of gold nanorods (AuNRs)...
August 15, 2017: Scientific Reports
Matthias Wurdack, Nils Lundt, Martin Klaas, Vasilij Baumann, Alexey V Kavokin, Sven Höfling, Christian Schneider
Strong light matter coupling between excitons and microcavity photons, as described in the framework of cavity quantum electrodynamics, leads to the hybridization of light and matter excitations. The regime of collective strong coupling arises, when various excitations from different host media are strongly coupled to the same optical resonance. This leads to a well-controllable admixture of various matter components in three hybrid polariton modes. Here, we study a cavity device with four embedded GaAs quantum wells hosting excitons that are spectrally matched to the A-valley exciton resonance of a MoSe2 monolayer...
August 15, 2017: Nature Communications
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