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https://www.readbyqxmd.com/read/28731691/singlet-oxygen-photophysics-in-liquid-solvents-converging-on-a-unified-picture
#1
Mikkel Bregnhøj, Michael Westberg, Boris F Minaev, Peter R Ogilby
Singlet oxygen, O2(a(1)Δg), the lowest excited electronic state of molecular oxygen, is an omnipresent part of life on earth. It is readily formed through a variety of chemical and photochemical processes, and its unique reactions are important not just as a tool in chemical syntheses but also in processes that range from polymer degradation to signaling in biological cells. For these reasons, O2(a(1)Δg) has been the subject of intense activity in a broad distribution of scientific fields for the past ∼50 years...
July 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28728978/anticancer-drug-loaded-quantum-dots-engineered-polymeric-nanoparticles-diagnosis-therapy-combined-approach
#2
D Belletti, G Riva, M Luppi, G Tosi, F Forni, M A Vandelli, B Ruozi, F Pederzoli
Primary Effusion Lymphoma (PEL) is an HHV-8-related non Hodgkin lymphoma localized in body cavities (as pleural, peritoneal and pericardial) presenting lymphomatous effusion that, until now, lack of an effective therapy. Curcumin was reported to display pro-apoptotic effect via the inhibition of the JAK/STAT pathway, that is overexpressed in PEL cells, as consequence of virus infection. The administration of curcumin is severely restricted by its physicochemical properties, mainly its low solubility in biological fluid and consequently low bioavailability...
July 17, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28726387/aryl-substituted-ruthenium-ii-complexes-a-strategy-for-enhanced-photocleavage-and-efficient-dna-binding
#3
Felipe Diógenes Abreu, Tercio de F Paulo, Marcelo H Gehlen, Rômulo A Ando, Luiz G F Lopes, Ana Cláudia S Gondim, Mayron A Vasconcelos, Edson H Teixeira, Eduardo Henrique Silva Sousa, Idalina Maria Moreira de Carvalho
Ruthenium polypyridine complexes have shown promise as agents for photodynamic therapy (PDT) and tools for molecular biology (chromophore-assisted light inactivation). To accomplish these tasks, it is important to have at least target selectivity and great reactive oxygen species (ROS) photogeneration: two properties that are not easily found in the same molecule. To prepare such new agents, we synthesized two new ruthenium complexes that combine an efficient DNA binding moiety (dppz ligand) together with naphthyl-modified (1) and anthracenyl-modified (2) bipyridine as a strong ROS generator bound to a ruthenium complex...
July 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28721419/highly-fluorescent-hyperbranched-bodipy-based-conjugated-polymer-dots-for-cellular-imaging
#4
Rongxin Du, Shuang Cui, Zezhou Sun, Ming Liu, Yong Zhang, Qiong Wu, Changfeng Wu, Fengyun Guo, Liancheng Zhao
The first hyperbranched BODIPY-based conjugated polymer dots (Pdots) were reported. The Pdots showed quantum yields of as high as 22%, which is 40% higher than their linear counterparts. The Pdots were successfully applied in cell-labelling applications. These results demonstrated that hyperbranched polymers are a very promising material for biological imaging and applications.
July 19, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28718770/benchmarking-gate-geant4-for-sup-16-sup-o-ion-beam-therapy
#5
Andreas Franz Resch, Hermann Fuchs, Dietmar Georg
Oxygen (<sup>16</sup>O) ions are a potential alternative to carbon ions in ion beam therapy. Their enhanced linear energy transfer indicates a higher relative biological effectiveness and a reduced oxygen enhancement ratio. Due to the limited availability of <sup>16</sup>O ion beams, Monte Carlo (MC) transport codes are important research tools to investigate their potential. The purpose of this study was to validate GATE/Geant4 for <sup>16</sup>O ion beam therapy on experimental data from literature...
July 18, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28715606/enzymatic-mechanisms-of-biological-magnetic-sensitivity
#6
Ulyana G Letuta, Vitaly L Berdinskiy, Chikako Udagawa, Yoshifumi Tanimoto
Primary biological magnetoreceptors in living organisms is one of the main research problems in magnetobiology. Intracellular enzymatic reactions accompanied by electron transfer have been shown to be receptors of magnetic fields, and spin-dependent ion-radical processes can be a universal mechanism of biological magnetosensitivity. Magnetic interactions in intermediate ion-radical pairs, such as Zeeman and hyperfine (HFI) interactions, in accordance with proposed strict quantum mechanical theory, can determine magnetic-field dependencies of reactions that produce biologically important molecules needed for cell growth...
July 17, 2017: Bioelectromagnetics
https://www.readbyqxmd.com/read/28711053/representations-in-neural-network-based-empirical-potentials
#7
Ekin D Cubuk, Brad D Malone, Berk Onat, Amos Waterland, Efthimios Kaxiras
Many structural and mechanical properties of crystals, glasses, and biological macromolecules can be modeled from the local interactions between atoms. These interactions ultimately derive from the quantum nature of electrons, which can be prohibitively expensive to simulate. Machine learning has the potential to revolutionize materials modeling due to its ability to efficiently approximate complex functions. For example, neural networks can be trained to reproduce results of density functional theory calculations at a much lower cost...
July 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28709375/examining-the-roles-of-emulsion-droplet-size-and-surfactant-in-the-interfacial-instability-based-fabrication-process-of-micellar-nanocrystals
#8
Yuxiang Sun, Ling Mei, Ning Han, Xinyi Ding, Caihao Yu, Wenjuan Yang, Gang Ruan
The interfacial instability process is an emerging general method to fabricate nanocrystal-encapsulated micelles (also called micellar nanocrystals) for biological detection, imaging, and therapy. The present work utilized fluorescent semiconductor nanocrystals (quantum dots or QDs) as the model nanocrystals to investigate the interfacial instability-based fabrication process of nanocrystal-encapsulated micelles. Our experimental results suggest intricate and intertwined roles of the emulsion droplet size and the surfactant poly (vinyl alcohol) (PVA) used in the fabrication process of QD-encapsulated poly (styrene-b-ethylene glycol) (PS-PEG) micelles...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28708324/ferrichrome-has-found-its-match-biomimetic-analogs-with-diversified-activity-map-discrete-microbial-targets
#9
Jenny Besserglick, Evgenia Olshvang, Agnieszka Szebesczyk, Joseph Englander, Dana Levinson, Yitzhak Hadar, Elzbieta Gumienna-Kontecka, Abraham Shanzer
Siderophores provide an established platform for studying molecular recognition principles in biological systems. Herein we describe the preparation of ferrichrome biomimetic analogs varying in length and polarity of the amino acid chain separating between the tripodal scaffold and the pendent FeIII chelating hydroxamic acid groups. Spectroscopic and potentiometric titrations determined their iron affinity to be within the range of efficient chelators. Microbial growth promotion and iron uptake studies were conducted on E...
July 14, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28699321/indolizine-squaraines-nir-fluorescent-materials-with-molecular-engineered-stokes-shifts
#10
Louis Edward McNamara, Tana A Rill, Aron J Huckaba, Vigneshraja Ganeshraj Ganeshraj, Jacqueline Gayton, Rachael A Nelson, Emily Anne Sharpe, Amala Dass, Nathan I Hammer, Jared Heath Delcamp
The development of deep red and near infrared emissive materials with high quantum yields is an important challenge. Several classes of squaraine dyes have demonstrated high quantum yields, but require significantly red-shifted absorptions to access the NIR window. Additionally, squaraine dyes have typically shown narrow Stokes shifts, which limits their use in living biological imaging applications due to dye emission interference with the light source. Through the incorporation of indolizine heterocycles we have synthesized novel indolizine squaraine dyes with increased Stokes shifts (>50 nm increase) and absorptions substantially further into the NIR region than an indoline squaraine benchmark (726 nm versus 659 nm absorption maxima)...
July 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28692933/contrast-enhancement-of-nanomaterials-using-phase-plate-stem
#11
Hiroki Minoda, Takayuki Tamai, Yuya Ohmori, Hirofumi Iijima
Visualizing materials composed of light elements is difficult, and the development of an imaging method that enhances the phase contrast of such materials has been of much interest. In this study, we demonstrate phase-plate scanning transmission electron microscopy (P-STEM), which we developed recently, and its application to nanomaterials. An amorphous carbon film with a small hole in its center was used to control the phase of incident electron waves, and the phase-contrast transfer function (PCTF) was modified from sine-type to cosine-type...
July 4, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28692869/%C3%AE-order-spectrophotokinetic-characterisation-and-quantification-of-trans-cis-oxyresveratrol-reactivity-photodegradation-and-actinometry
#12
Mounir Maafi, Mohammed Ahmed Al-Qarni
A new Φ-order kinetic method was proposed in this study for the investigation of trans-cis photoisomerization reaction of Oxyresveratrol (ORVT) subjected to non-isosbestic irradiation. In ethanolic media, it has been proven that forward (ΦA→B(λirr)) and reverse (ΦB→A(λirr)) reaction quantum yields were dependent on the monochromatic irradiation wavelength according to sigmoid patterns over the spectral ranges of their electronic absorption (260-360nm). An 11.4- and 6.6-fold increases were recorded for ΦB→A(λirr) and ΦA→B(λirr), respectively...
July 2, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28688060/community-based-study-recruitment-of-american-indian-cigarette-smokers-and-electronic-cigarette-users
#13
Dana Mowls Carroll, Lacy S Brame, Lancer D Stephens, Theodore L Wagener, Janis E Campbell, Laura A Beebe
Data on the effectiveness of strategies for the recruitment of American Indians (AIs) into research is needed. This study describes and compares methods for identifying and recruiting AI tobacco users into a pilot study. Community-based strategies were used to recruit smokers (n = 35), e-cigarette users (n = 28), and dual users (n = 32) of AI descent. Recruitment was considered proactive if study staff contacted the individual at a pow wow, health fair, or vape shop and participation on-site or reactive if the individual contacted the study staff and participation occurred later...
July 7, 2017: Journal of Community Health
https://www.readbyqxmd.com/read/28685463/in-vivo-epr-resolution-enhancement-using-techniques-known-from-quantum-computing-spin-technology
#14
Robabeh Rahimi, Howard J Halpern, Takeji Takui
A crucial issue with in vivo biological/medical EPR is its low signal-to-noise ratio, giving rise to the low spectroscopic resolution. We propose quantum hyperpolarization techniques based on 'Heat Bath Algorithmic Cooling', allowing possible approaches for improving the resolution in magnetic resonance spectroscopy and imaging.
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28677653/fret-mediated-long-range-wavelength-transformation-by-photoconvertible-fluorescent-proteins-as-an-efficient-mechanism-to-generate-orange-red-light-in-symbiotic-deep-water-corals
#15
Elena Bollati, Daniel Plimmer, Cecilia D'Angelo, Jörg Wiedenmann
Photoconvertible fluorescent proteins (pcRFPs) are a group of fluorophores that undergo an irreversible green-to-red shift in emission colour upon irradiation with near-ultraviolet (near-UV) light. Despite their wide application in biotechnology, the high-level expression of pcRFPs in mesophotic and depth-generalist coral species currently lacks a biological explanation. Additionally, reduced penetration of near-UV wavelengths in water poses the question whether light-driven photoconversion is relevant in the mesophotic zone, or whether a different mechanism is involved in the post-translational pigment modification in vivo...
July 4, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28675443/rapid-and-accurate-assessment-of-gpcr-ligand-interactions-using-the-fragment-molecular-orbital-based-density-functional-tight-binding-method
#16
Inaki Morao, Dmitri G Fedorov, Roger Robinson, Michelle Southey, Andrea Townsend-Nicholson, Mike J Bodkin, Alexander Heifetz
The reliable and precise evaluation of receptor-ligand interactions and pair-interaction energy is an essential element of rational drug design. While quantum mechanical (QM) methods have been a promising means by which to achieve this, traditional QM is not applicable for large biological systems due to its high computational cost. Here, the fragment molecular orbital (FMO) method has been used to accelerate QM calculations, and by combining FMO with the density-functional tight-binding (DFTB) method we are able to decrease computational cost 1000 times, achieving results in seconds, instead of hours...
July 4, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/28674011/elucidating-reaction-mechanisms-on-quantum-computers
#17
Markus Reiher, Nathan Wiebe, Krysta M Svore, Dave Wecker, Matthias Troyer
With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations...
July 3, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28672691/the-relationship-between-the-length-of-surface-ligand-and-effects-of-cdte-quantum-dots-on-the-physiological-functions-of-isolated-mitochondria
#18
Xun Xiang, Can Wu, Bo-Rui Zhang, Tao Gao, Jie Zhao, Long Ma, Feng-Lei Jiang, Yi Liu
The potential toxicity of Quantum dots (QDs) should be assessed comprehensively for their fast spreading applications. Many studies have shown the toxicity of QDs is associated with their surface ligands. In this work, two analog ligands with one carbon difference, 2-mercaptoacetic acid (TGA) and 3-mercaptopropionic acid (MPA) were used as coating materials in the syntheses of two types of CdTe QDs with similar physicochemical properties. Then the biological effects of QDs on isolated mitochondria were studied...
June 21, 2017: Chemosphere
https://www.readbyqxmd.com/read/28672183/an-instrumental-approach-to-combining-confocal-microspectroscopy-and-3d-scanning-probe-nanotomography
#19
Konstantin E Mochalov, Anton A Chistyakov, Daria O Solovyeva, Alexey V Mezin, Vladimir A Oleinikov, Ivan S Vaskan, Michael Molinari, Igor I Agapov, Igor Nabiev, Anton E Efimov
In the past decade correlative microscopy, which combines the potentials of different types of high-resolution microscopies with a variety of optical microspectroscopy techniques, has been attracting increasing attention in material science and biological research. One of outstanding solutions in this area is the combination of scanning probe microscopy (SPM), which provides data on not only the topography, but also the spatial distribution of a wide range of physical properties (elasticity, conductivity, etc...
June 21, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28663772/proton-environments-in-biomimetic-calcium-phosphates-formed-from-mesoporous-bioactive-cao-sio2-p2o5-glasses-in-vitro-insights-from-solid-state-nmr
#20
Renny Mathew, Claudia Turdean-Ionescu, Yang Yu, Baltzar Stevensson, Isabel Izquierdo-Barba, Ana García, Daniel Arcos, María Vallet-Regí, Mattias Edén
When exposed to body fluids, mesoporous bioactive glasses (MBGs) of the CaO-SiO2-P2O5 system develop a bone-bonding surface layer that initially consists of amorphous calcium phosphate (ACP), which transforms into hydroxy-carbonate apatite (HCA) with a very similar composition as bone/dentin mineral. Information from various (1)H-based solid-state nuclear magnetic resonance (NMR) experiments was combined to elucidate the evolution of the proton speciations both at the MBG surface and within each ACP/HCA constituent of the biomimetic phosphate layer formed when each of three MBGs with distinct Ca, Si, and P contents was immersed in a simulated body fluid (SBF) for variable periods between 15 min and 30 days...
June 22, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
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