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Journal of Physical Chemistry. C, Nanomaterials and Interfaces

V Vonk, N Khorshidi, A Stierle
Nickel nanoparticles supported by the yttria-stabilized zirconia (111) surface show several preferential epitaxial relationships, as revealed by in situ X-ray diffraction. The two main nanoparticle orientations are found to have their [111] direction parallel to the substrate surface normal and ∼41.3 degrees tilted from this direction. The former orientation is described by a cube-on-cube stacking at the oxide-metal interface and the latter by a so-called coherent tilt strain-relieving mechanism, which is hitherto unreported for nanoparticles in literature...
February 9, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Thomas S Blacker, WeiYue Chen, Edward Avezov, Richard J Marsh, Michael R Duchen, Clemens F Kaminski, Angus J Bain
Most fluorescent proteins exhibit multiexponential fluorescence decays, indicating a heterogeneous excited state population. FRET between fluorescent proteins should therefore involve multiple energy transfer pathways. We recently demonstrated the FRET pathways between EGFP and mCherry (mC), upon the dimerization of 3-phosphoinositide dependent protein kinase 1 (PDK1), to be highly restricted. A mechanism for FRET restriction based on a highly unfavorable κ(2) orientation factor arising from differences in donor-acceptor transition dipole moment angles in a far from coplanar and near static interaction geometry was proposed...
January 26, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Tonya M Atkins, Jeffrey H Walton, Mani P Singh, Shreyashi Ganguly, Oliver Janka, Angelique Y Louie, Susan M Kauzlarich
Water-soluble poly(allylamine) Mn(2+)-doped Si (SiMn) nanoparticles (NPs) were prepared and show promise for biologically related applications. The nanoparticles show both strong photoluminescence and good magnetic resonance contrast imaging. The morphology and average diameter were obtained through transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM); spherical crystalline Si NPs with an average diameter of 4.2 ± 0.7 nm were observed. The doping maximum obtained through this process was an average concentration of 0...
January 26, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Matthew Witman, Sanliang Ling, Andrzej Gladysiak, Kyriakos C Stylianou, Berend Smit, Ben Slater, Maciej Haranczyk
We present the in silico design of a MOF-74 analogue, hereon known as M2(DHFUMA) [M = Mg, Fe, Co, Ni, Zn], with enhanced small-molecule adsorption properties over the original M2(DOBDC) series. Constructed from 2,3-dihydroxyfumarate (DHFUMA), an aliphatic ligand which is smaller than the aromatic 2,5-dioxidobenzene-1,4-dicarboxylate (DOBDC), the M2(DHFUMA) framework has a reduced channel diameter, resulting in higher volumetric density of open metal sites and significantly improved volumetric hydrogen (H2) storage potential...
January 19, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Daniela Meroni, Leonardo Lo Presti, Giovanni Di Liberto, Michele Ceotto, Robert G Acres, Kevin C Prince, Roberto Bellani, Guido Soliveri, Silvia Ardizzone
The surface functionalization of TiO2-based materials with alkylsilanes is attractive in several cutting-edge applications, such as photovoltaics, sensors, and nanocarriers for the controlled release of bioactive molecules. (3-Aminopropyl)triethoxysilane (APTES) is able to self-assemble to form monolayers on TiO2 surfaces, but its adsorption geometry and solar-induced photodegradation pathways are not well understood. We here employ advanced experimental (XPS, NEXAFS, AFM, HR-TEM, and FT-IR) and theoretical (plane-wave DFT) tools to investigate the preferential interaction mode of APTES on anatase TiO2...
January 12, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Aristides D Zdetsis, E N Economou
It is illustrated and computationally verified by ab initio density functional theory and simple but powerful order-of-magnitude arguments, based on deformation energy ΔEdef in relation to the uncertainty principle, that the conductivity and aromaticity of graphene and graphene-based structures, such as graphene dots, antidots, and nanoribbons, are negatively interrelated for π aromatic structures, in agreement with recent experimental data. However, for σ aromaticity, the interrelation could be positive, especially for extended periodic structures...
December 29, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Danila A Barskiy, Oleg G Salnikov, Roman V Shchepin, Matthew A Feldman, Aaron M Coffey, Kirill V Kovtunov, Igor V Koptyug, Eduard Y Chekmenev
Parahydrogen-induced polarization (PHIP) is an NMR hyperpolarization technique that increases nuclear spin polarization by orders of magnitude, and it is particularly well-suited to study hydrogenation reactions. However, the use of high-field NMR spectroscopy is not always possible, especially in the context of potential industrial-scale reactor applications. On the other hand, the direct low-field NMR detection of reaction products with enhanced nuclear spin polarization is challenging due to near complete signal cancellation from nascent parahydrogen protons...
December 29, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Daniele Selli, Cristiana Di Valentin
In biomedical applications, TiO2 nanoparticles are generally coated with polymers to prevent agglomeration, improve biocompatibility, and reduce cytotoxicity. Although the synthesis processes of such composite compounds are well established, there is still a substantial lack of information on the nature of the interaction between the titania surface and the organic macromolecules. In this work, the adsorption of polyethylene glycol (PEG) on the TiO2 (101) anatase surface is modeled by means of dispersion-corrected density functional theory (DFT-D2) calculations...
December 29, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Silvio Pipolo, Stefano Corni
The optical properties of molecules close to plasmonic nanostructures greatly differ from their isolated molecule counterparts. To theoretically investigate such systems from a quantum-chemistry perspective, one has to take into account that the plasmonic nanostructure (e.g., a metal nanoparticle-NP) is often too large to be treated atomistically. Therefore, a multiscale description, where the molecule is treated by an ab initio approach and the metal NP by a lower level description, is needed. Here we present an extension of one such multiscale model [Corni, S...
December 22, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Nicole L Ritzert, Thomas P Moffat
The interaction between electrodeposition of Ni and electrolyte breakdown, namely the hydrogen evolution reaction (HER) via H3O(+) and H2O reduction, was investigated under well-defined mass transport conditions using ultramicroelectrodes (UME's) coupled with optical imaging, generation/collection scanning electrochemical microscopy (G/C-SECM), and preliminary microscale pH measurements. For 5 mmol/L NiCl2 + 0.1 mol/L NaCl, pH 3.0, electrolytes, the voltammetric current at modest overpotentials, i.e., between -0...
December 8, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Andrea Zen, Loïc M Roch, Stephen J Cox, Xiao Liang Hu, Sandro Sorella, Dario Alfè, Angelos Michaelides
Clay minerals are ubiquitous in nature, and the manner in which they interact with their surroundings has important industrial and environmental implications. Consequently, a molecular-level understanding of the adsorption of molecules on clay surfaces is crucial. In this regard computer simulations play an important role, yet the accuracy of widely used empirical force fields (FF) and density functional theory (DFT) exchange-correlation functionals is often unclear in adsorption systems dominated by weak interactions...
November 23, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Ailin Wang, Y Randika Perera, Mackenzie B Davidson, Nicholas C Fitzkee
Gold nanoparticle- (AuNP-) protein conjugates are potentially useful in a broad array of diagnostic and therapeutic applications, but the physical basis of the simultaneous adsorption of multiple proteins onto AuNP surfaces remains poorly understood. Here, we investigate the contribution of electrostatic interactions to protein-AuNP binding by studying the pH-dependent binding behavior of two proteins, GB3 and ubiquitin. For both proteins, binding to 15-nm citrate-coated AuNPs closely tracks with the predicted net charge using standard pKa values, and a dramatic reduction in binding is observed when lysine residues are chemically methylated...
October 27, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Natalie A Belsey, David J H Cant, Caterina Minelli, Joyce R Araujo, Bernd Bock, Philipp Brüner, David G Castner, Giacomo Ceccone, Jonathan D P Counsell, Paul M Dietrich, Mark H Engelhard, Sarah Fearn, Carlos E Galhardo, Henryk Kalbe, Jeong Won Kim, Luis Lartundo-Rojas, Henry S Luftman, Tim S Nunney, Johannes Pseiner, Emily F Smith, Valentina Spampinato, Jacobus M Sturm, Andrew G Thomas, Jon P W Treacy, Lothar Veith, Michael Wagstaffe, Hai Wang, Meiling Wang, Yung-Chen Wang, Wolfgang Werner, Li Yang, Alexander G Shard
We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS...
October 27, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Battulga Munkhbat, Johannes Ziegler, Hannes Pöhl, Christian Wörister, Dmitry Sivun, Markus C Scharber, Thomas A Klar, Calin Hrelescu
Here, we report that hybrid multilayered plasmonic nanostars can be universally used as feedback agents for coherent random lasing in polar or nonpolar solutions containing gain material. We show that silver-enhancement of gold nanostars reduces the pumping threshold for coherent random lasing substantially for both a typical dye (R6G) and a typical fluorescent polymer (MEH-PPV). Further, we reveal that the lasing intensity and pumping threshold of random lasers based on silver-enhanced gold nanostars are not influenced by the silica coating, in contrast to gold nanostar-based random lasers, where silica-coated gold nanostars support only amplified spontaneous emission but no coherent random lasing...
October 20, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
C J Powell, W S M Werner, A G Shard, D G Castner
We evaluated two methods for determining shell thicknesses of core-shell nanoparticles (NPs) by X-ray photoelectron spectroscopy (XPS). One of these methods had been developed for determining thicknesses of films on a planar substrate while the other was developed specifically for NPs. Our evaluations were based on simulated Cu 2p3/2 spectra from Cu-core/Cu-shell NPs with a wide range of core diameters and shell thicknesses. Copper was chosen for our tests because elastic-scattering effects for Cu 2p3/2 photoelectrons excited by Al Kα X-rays are known to be strong...
October 6, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Bernhard C Bayer, David A Bosworth, F Benjamin Michaelis, Raoul Blume, Gerlinde Habler, Rainer Abart, Robert S Weatherup, Piran R Kidambi, Jeremy J Baumberg, Axel Knop-Gericke, Robert Schloegl, Carsten Baehtz, Zoe H Barber, Jannik C Meyer, Stephan Hofmann
Nanocomposite thin films comprised of metastable metal carbides in a carbon matrix have a wide variety of applications ranging from hard coatings to magnetics and energy storage and conversion. While their deposition using nonequilibrium techniques is established, the understanding of the dynamic evolution of such metastable nanocomposites under thermal equilibrium conditions at elevated temperatures during processing and during device operation remains limited. Here, we investigate sputter-deposited nanocomposites of metastable nickel carbide (Ni3C) nanocrystals in an amorphous carbon (a-C) matrix during thermal postdeposition processing via complementary in situ X-ray diffractometry, in situ Raman spectroscopy, and in situ X-ray photoelectron spectroscopy...
October 6, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Kayla S B Culver, Yu Jin Shin, Matthew W Rotz, Thomas J Meade, Mark C Hersam, Teri W Odom
Gold nanostars functionalized with Gd(III) have shown significant promise as contrast agents for magnetic resonance imaging (MRI) because of their anisotropic, branched shape. However, the size and shape polydispersity of as-synthesized gold nanostars have precluded efforts to develop a rigorous relationship between the gold nanostar structure (e.g., number of branches) and relaxivity of surface-bound Gd(III). This paper describes the use of a centrifugal separation method that can produce structurally refined populations of gold nanostars and is compatible with Gd(III) functionalization...
September 29, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Marina Gühlke, Zsuzsanna Heiner, Janina Kneipp
A thiol-modified carotene, 7'-apo-7'-(4-mercaptomethylphenyl)-β-carotene, was used to obtain nonresonant surface-enhanced Raman scattering (SERS) spectra of carotene at an excitation wavelength of 1064 nm, which were compared with resonant SERS spectra at an excitation wavelength of 532 nm. These spectra and surface-enhanced hyper-Raman scattering (SEHRS) spectra of the functionalized carotene were compared with the spectra of nonmodified β-carotene. Using SERS, normal Raman, and SEHRS spectra, all obtained for the resonant case, the interaction of the carotene molecules with silver nanoparticles, as well as the influence of the resonance enhancement and the SERS enhancement on the spectra, were investigated...
September 22, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Matthew R Bailey, R Scott Martin, Zachary D Schultz
The strength of the analyte-substrate interaction is a key component when evaluating the observed enhancements in surface-enhanced Raman scattering (SERS) detection. By performing Raman and electrochemical measurements on a series of neurotransmitters, including dopamine, serotonin, norepinephrine, and epinephrine, as well as catechol as it allows us to examine the diol moiety without the side chains present, we were able to correlate surface chemistry with the measured SERS signal and examine the oxidation mechanism of each analyte...
September 22, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Xin Zhao, M H Alizadeh, Björn M Reinhard
Hybrid structures containing plasmonic and photonic components can enhance light-matter interaction through both photonic and plasmonic modes and potentially their interactions. In this article, we systematically investigate the optical properties of nanoparticle-tipped silicon nanowires (NPTWs) and characterize their ability to enhance the fluorescence signal of two cyanine dyes (Cy3 and Cy5) selectively bound to the gold tip. Although both gold and silicon components contribute to the fluorescence signal enhancement, the experimentally observed strong morphology dependence of the fluorescence emission enhancement is demonstrated to depend on tunable leaky modes of the silicon nanowires...
September 22, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
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