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https://www.readbyqxmd.com/read/28335354/titanium-dioxide-nanoparticle-biomolecule-interactions-influence-oral-absorption
#1
Mi-Rae Jo, Jin Yu, Hyoung-Jun Kim, Jae Ho Song, Kyoung-Min Kim, Jae-Min Oh, Soo-Jin Choi
Titanium dioxide (TiO₂) nanoparticles (NPs) have been widely applied in various industrial fields, such as electronics, packaging, food, and cosmetics. Accordingly, concerns about the potential toxicity of TiO₂ NPs have increased. In order to comprehend their in vivo behavior and potential toxicity, we must evaluate the interactions between TiO₂ NPs and biomolecules, which can alter the physicochemical properties and the fate of NPs under physiological conditions. In the present study, in vivo solubility, oral absorption, tissue distribution, and excretion kinetics of food grade TiO₂ (f-TiO₂) NPs were evaluated following a single-dose oral administration to rats and were compared to those of general grade TiO₂ (g-TiO₂) NPs...
November 29, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28334479/signal-induced-release-of-guests-from-a-photolatent-metal-phenolic-supramolecular-cage-and-its-hybrid-assemblies
#2
Chiyoung Park, Beom Joo Yang, Ki Beom Jeong, Chae Bin Kim, Seunghyun Lee, Bon-Cheol Ku
The coordination chemistry of plant polyphenols and metal ions can be used for coating various substrates and for creating modular superstructures. We herein explored this chemistry for the controlled release of guests from mesoporous silica nanoparticles (MSNs). The selective adsorption of tannic acids (TAs) on MSN silica walls opens the MSN mesoporous channels without disturbing mass transport. The channel may be closed by the coordination of TA with Cu(II) ions. Upon exposure to light, photolysis of Trojan horse guests (photoacid generators, PAGs) leads to acid generation, which enables the release of payloads by decomposing the outer coordination shell consisting of TA and Cu(II) ...
March 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28333451/aerosol-formation-from-oh-oxidation-of-the-volatile-cyclic-methyl-siloxane-cvms-decamethylcyclopentasiloxane
#3
Yue Wu, Murray V Johnston
Aerosol formation from OH oxidation of decamethylcyclopentasiloxane (D5, C10H30O5Si5), a cyclic volatile methyl siloxane (cVMS) found in consumer products, was studied in a flow-through photo chamber with and without the presence of ammonium sulfate seed aerosol. For the unseeded experiments, chemical characterization with high performance mass spectrometry showed that the molecular composition changed substantially with aerosol mass loading in the 1-12 μg/m3 range. Monomers (5 Si atoms/molecule) and dimers (10 Si atoms/molecule) dominated the mass spectra of aerosols at higher mass loadings while ring opened species (neither 5 nor 10 Si atoms/molecule) dominated the mass spectra of aerosols at lower mass loadings...
March 23, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28332817/basal-plane-ligand-functionalization-on-semiconducting-2h-mos2-monolayers
#4
Qi Ding, Kyle J Czech, Yuzhou Zhao, Jianyuan Zhai, Robert J Hamers, John C Wright, Song Jin
Molybdenum disulfide (MoS2) is a two-dimensional material promising for electronic, optical, and catalytic applications. To fully harness its potential, functionalization is essential to control its properties. However, MoS2 functionalization has been mostly limited to either 1T-phase MoS2 or the edges of 2H-phase MoS2, and the chemistry of covalent functionalization on the basal plane of 2H-MoS2 is poorly understood. Here we report a facile approach to covalently functionalize chemical vapor deposition (CVD) grown 2H-MoS2 monolayers (MLs), as well as mechanically exfoliated MoS2, via thiol conjugation at sulfur vacancies on the basal plane...
March 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28332663/surface-chemistry-of-group-ib-metals-and-related-oxides
#5
REVIEW
Weixin Huang, Guanghui Sun, Tian Cao
Understanding the surface chemistry of solid catalysts is of great importance for the rational design of structures of advanced catalysts; however, long-term challenges remain due to the complex and non-uniform catalyst structures and the lack of suitable characterization techniques. Surface chemistry studies of single-crystal-based model catalysts with well-defined surface structures under ultra-high vacuum conditions have been developed as one approach, but the so-called materials gap and pressure gap are sometimes encountered when the acquired understanding is extended to the industrial reaction conditions...
March 23, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28332662/can-all-bulk-phase-reactions-be-accelerated-in-microdroplets
#6
Shibdas Banerjee, Elumalai Gnanamani, Xin Yan, Richard N Zare
Recent studies have shown that microdroplet reactions are markedly accelerated compared to the corresponding bulk-phase reactions. This raises the question whether all reactions can be sped up by this means. We present a counter example, and we show that the reaction mechanism in microdroplets can differ sharply from that in bulk, especially because of the distinct microdroplet surface environment. This analysis helps to guide us how to choose and control reactions in microdroplets and provides a possible perspective on utilizing microdroplet chemistry to scale up synthesis...
March 23, 2017: Analyst
https://www.readbyqxmd.com/read/28328212/cu-ii-based-paramagnetic-probe-to-study-rna-protein-interactions-by-nmr
#7
Leah M Seebald, Christopher M DeMott, Srivathsan Ranganathan, Papa Nii Asare Okai, Anastasia Glazunova, Alan Chen, Alexander Shekhtman, Maksim Royzen
Paramagnetic NMR techniques allow for studying three-dimensional structures of RNA-protein complexes. In particular, paramagnetic relaxation enhancement (PRE) data can provide valuable information about long-range distances between different structural components. For PRE NMR experiments, oligonucleotides are typically spin-labeled using nitroxide reagents. The current work describes an alternative approach involving a Cu(II) cyclen-based probe that can be covalently attached to an RNA strand in the vicinity of the protein's binding site using "click" chemistry...
March 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28328191/enhancing-tumor-penetration-of-nanomedicines
#8
Qingxue Sun, Tarun Ojha, Fabian Kiessling, Twan Lammers, Yang Shi
Tumor-targeted nanomedicines have been extensively applied to alter the drawbacks and enhance the efficacy of chemotherapeutics. Despite the large number of preclinical nanomedicine studies showing initial success, their therapeutic benefit in the clinic has been rather modest, which is partially due to the inefficient tumor penetration caused by tumor microenvironment (high density of cells and extracellular matrix, increased interstitial fluid pressure). Furthermore, tumor penetration of nanomedicines is significantly influenced by physicochemical characteristics such as size, surface chemistry and shape...
March 22, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28327771/the-roles-of-surface-chemistry-dissolution-rate-and-delivered-dose-in-the-cytotoxicity-of-copper-nanoparticles
#9
Miao Shi, Karen L de Mesy Bentley, Goutam Palui, Hedi Mattoussi, Alison Elder, Hong Yang
The understanding of nanoparticle (NP) cytotoxicity is challenging because of incomplete information about physicochemical changes particles undergo once they come into contact with biological fluids. It is therefore essential to characterize changes in NP properties to better understand their biological fate and effects in mammalian cells. In this paper, we present a study on the effect of particle surface oxidation and dissolution rates of Cu NPs. Particle dissolution, cell-associated Cu doses, and oxidative stress responses in A549 luciferase reporter cells were examined for Cu NPs modified with mercaptocarboxylic acids with different carbon chain lengths and a thiotic acid appended-PEG ligand (TA)...
March 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28327733/surface-chemistry-of-propanal-2-propenol-and-1-propanol-on-ru-001
#10
Dominic A Esan, Michael Trenary
Adsorption and thermal chemistry of propanal, 2-propenol, and 1-propanol on Ru(001) were studied using temperature programmed reaction spectroscopy (TPRS) and reflection absorption infrared spectroscopy (RAIRS). The results show that each molecule adsorbs molecularly at 90 K and displays the same spectral features as observed for the corresponding liquids after 1.0 L exposures. 2-Propenol was found to molecularly desorb at 200 K, dehydrate to yield propene around 130 K, isomerize to propanal at 180 K, and hydrogenate to 1-propanol at 220 K...
March 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28327664/bioactive-silicon-nitride-a-new-therapeutic-material-for-osteoarthropathy
#11
Giuseppe Pezzotti, Elia Marin, Tetsuya Adachi, Alfredo Rondinella, Francesco Boschetto, Wenliang Zhu, Nobuhiko Sugano, Ryan M Bock, Bryan McEntire, Sonny B Bal
While the reciprocity between bioceramics and living cells is complex, it is principally governed by the implant's surface chemistry. Consequently, a deeper understanding of the chemical interactions of bioceramics with living tissue could ultimately lead to new therapeutic strategies. However, the physical and chemical principles that govern these interactions remain unclear. The intricacies of this biological synergy are explored within this paper by examining the peculiar surface chemistry of a relatively new bioceramic, silicon nitride (Si3N4)...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28327642/surface-chemistry-of-rare-earth-oxide-surfaces-at-ambient-conditions-reactions-with-water-and-hydrocarbons
#12
Elçin Külah, Laurent Marot, Roland Steiner, Andriy Romanyuk, Thomas A Jung, Aneliia Wäckerlin, Ernst Meyer
Rare-earth (RE) oxide surfaces are of significant importance for catalysis and were recently reported to possess intrinsic hydrophobicity. The surface chemistry of these oxides in the low temperature regime, however, remains to a large extent unexplored. The reactions occurring at RE surfaces at room temperature (RT) in real air environment, in particular, in presence of polycyclic aromatic hydrocarbons (PAHs), were not addressed until now. Discovering these reactions would shed light onto intermediate steps occurring in automotive exhaust catalysts before reaching the final high operational temperature and full conversion of organics...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28327297/first-proof-of-bismuth-oxide-nanoparticles-as-efficient-radiosensitisers-on-highly-radioresistant-cancer-cells
#13
Callum Stewart, Konstantin Konstantinov, Sally McKinnon, Susanna Guatelli, Michael Lerch, Anatoly Rosenfeld, Moeava Tehei, Stéphanie Corde
This study provides the first proof of the novel application of bismuth oxide as a radiosensitiser. It was shown that on the highly radioresistant 9L gliosarcoma cell line, bismuth oxide nanoparticles sensitise to both kilovoltage (kVp) or megavoltage (MV) X-rays radiation. 9L cells were exposed to a concentration of 50μg.mL(-1) of nanoparticle before irradiation at 125kVp and 10MV. Sensitisation enhancement ratios of 1.48 and 1.25 for 125kVp and 10MV were obtained in vitro, respectively. The radiation enhancement of the nanoparticles is postulated to be a combination of the high Z nature of the bismuth (Z=83), and the surface chemistry...
November 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/28323482/constraints-on-the-early-terrestrial-surface-uv-environment-relevant-to-prebiotic-chemistry
#14
Sukrit Ranjan, Dimitar D Sasselov
The UV environment is a key boundary condition to abiogenesis. However, considerable uncertainty exists as to planetary conditions and hence surface UV at abiogenesis. Here, we present two-stream multilayer clear-sky calculations of the UV surface radiance on Earth at 3.9 Ga to constrain the UV surface fluence as a function of albedo, solar zenith angle (SZA), and atmospheric composition. Variation in albedo and latitude (through SZA) can affect maximum photoreaction rates by a factor of >10.4; for the same atmosphere, photoreactions can proceed an order of magnitude faster at the equator of a snowball Earth than at the poles of a warmer world...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28323413/designing-morphology-in-epitaxial-silicon-nanowires-the-role-of-gold-surface-chemistry-and-phosphorus-doping
#15
Seokhyoung Kim, David J Hill, Christopher W Pinion, Joseph D Christesen, James R McBride, James F Cahoon
Vertically-aligned semiconductor nanowires (NWs) have many potential applications for NW-based technologies, ranging from solar cells to intracellular sensors. Aligned NWs can be fabricated by top-down etching of planar wafers or synthesized from the bottom-up using the vapor-liquid-solid (VLS) mechanism to induce epitaxial growth on lattice-matched substrates. The VLS process permits the modulation of dopants along the NW growth axis, which, if combined with dopant-dependent wet-chemical etching, can be used to encode precise morphology...
March 21, 2017: ACS Nano
https://www.readbyqxmd.com/read/28322560/subphthalocyanines-axially-substituted-with-a-tetracyanobuta-1-3-diene-aniline-moiety-synthesis-structure-and-physicochemical-properties
#16
Kim A Winterfeld, Giulia Lavarda, Julia Guilleme, Michael Sekita, Dirk M Guldi, Tomas Torres, Giovanni Bottari
A 1,1,4,4-tetracyanobuta-1,3-diene (TCBD)-aniline moiety has been introduced, for the first time, at the axial position of two subphthalocyanines (SubPcs) peripherally substituted with hydrogen (H12SubPc) or fluorine atoms (F12SubPc). Single-crystal X-ray analysis of both SubPc-TCBD-aniline systems showed that each conjugate is a racemic mixture of two atropisomers resulting from the almost orthogonal geometry adopted by the axial TCBD unit, which were separated by chiral HPLC. Remarkably, the single-crystal X-ray structure of one atropisomer of each SubPc-TCBD-aniline conjugate has been solved allowing to unambiguously assign the atropisomers' absolute configuration, something, to the best of our knowledge, unprecedented in TCBD-based conjugates...
March 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28322472/molecular-chemistry-and-engineering-of-boron-modified-polyorganosilazanes-as-new-processable-and-functional-sibcn-precursors
#17
Samuel Bernard, Antoine Viard, Diane Fonblanc, Marion Schmidt, Abhijeet Lale, Chrystelle Salameh, Anne Soleilhavoup, Mélanie Wynn, Philippe Champagne, Sophie Cerneaux, Florence Babonneau, Georges Chollon, Fabrice Rossignol, Christel Gervais
A series of boron-modified polyorganosilazanes was synthesized from a poly(vinylmethyl-co-methyl)silazane and controlled borane dimethyl sulfide amounts. The role of the chemistry behind their syntheses has been studied in details by solid-state NMR, FT-IR and elemental analyses. Then, the intimate relationship between the chemistry and the processability of these polymers was discussed. Polymers with low boron contents display the appropriate requirements for facile processing in solution such as impregnation of host carbon materials resulting in the design of mesoporous monoliths with high specific surface area after pyrolysis...
March 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28322388/understanding-surface-site-structures-and-properties-by-first-principles-calculations-an-experimental-point-of-view
#18
Aleix Comas-Vives, Kim Larmier, Christophe Copéret
The characterization of the active sites in heterogeneous catalysts is highly challenging and hinders the rational development and design of better catalysts. One approach to achieve this goal is Surface Organometallic Chemistry (SOMC), which allows generation of well-defined active sites characterized at the molecular level using spectroscopic methods. Due to many advances in the field and the increase of computational power, Computational Chemistry (CompChem) plays a key role in providing an atomistic understanding of these systems and the nature of the active sites...
March 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28322139/heparin-tailored-biopolymeric-nanocarriers-in-site-specific-delivery-a-systematic-review
#19
Ashish Garg, Rajeev Sharma, Vikas Pandey, Vaibhav Patel, Awesh K Yadav
The combination of nanocarriers and biological molecules is of intense interest because of the synergistic properties offered by such newly synthesized composites. Heparin conjugated to nanomaterials has recently been investigated for its beneficial chemical and biological properties and its capacity to improve the biocompatibility of nanocarriers, increasing their performance in various biological applications. A variety of recent research combines heparin and nanomaterials for a myriad of uses. For example, heparin has been conjugated to the surface of magnetic and metallic nanoparticles, biodegradable and nondegradable synthetic polymers, nanocomposites, dendrimers, and the like...
2017: Critical Reviews in Therapeutic Drug Carrier Systems
https://www.readbyqxmd.com/read/28320909/theoretical-and-computational-studies-of-non-equilibrium-and-non-statistical-dynamics-in-the-gas-phase-in-the-condensed-phase-and-at-interfaces
#20
Riccardo Spezia, Emilio Martínez-Nuñez, Saulo Vazquez, William L Hase
In this Introduction, we show the basic problems of non-statistical and non-equilibrium phenomena related to the papers collected in this themed issue. Over the past few years, significant advances in both computing power and development of theories have allowed the study of larger systems, increasing the time length of simulations and improving the quality of potential energy surfaces. In particular, the possibility of using quantum chemistry to calculate energies and forces 'on the fly' has paved the way to directly study chemical reactions...
April 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
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