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https://www.readbyqxmd.com/read/28817145/coherent-electronic-and-nuclear-dynamics-in-a-rhodamine-heterodimer-dna-supramolecular-complex
#1
M Cipolloni, B Fresch, I Occhiuto, P Rukin, K G Komarova, A Cecconello, I Willner, R D Levine, F Remacle, E Collini
Elucidating the role of quantum coherences in energy migration within biological and artificial multichromophoric antenna systems is the subject of an intense debate. It is also a practical matter because of the decisive implications for understanding the biological processes and engineering artificial materials for solar energy harvesting. A supramolecular rhodamine heterodimer on a DNA scaffold was suitably engineered to mimic the basic donor-acceptor unit of light-harvesting antennas. Ultrafast 2D electronic spectroscopic measurements allowed identifying clear features attributable to a coherent superposition of dimer electronic and vibrational states contributing to the coherent electronic charge beating between the donor and the acceptor...
August 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28814630/inverted-region-electron-transfer-as-a-mechanism-for-enhancing-photosynthetic-solar-energy-conversion-efficiency
#2
Hiroki Makita, Gary Hastings
In all photosynthetic organisms, light energy is used to drive electrons from a donor chlorophyll species via a series of acceptors across a biological membrane. These light-induced electron-transfer processes display a remarkably high quantum efficiency, indicating a near-complete inhibition of unproductive charge recombination reactions. It has been suggested that unproductive charge recombination could be inhibited if the reaction occurs in the so-called inverted region. However, inverted-region electron transfer has never been demonstrated in any native photosynthetic system...
August 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28808262/generation-of-broadband-ultraviolet-frequency-entangled-photons-using-cavity-quantum-plasmonics
#3
Hisaki Oka
Application of quantum entangled photons is now extending to various fields in physics, chemistry and biology. In particular, in terms of application to molecular science, broadband ultraviolet frequency-entangled photons are desired because molecules inducing photochemical reactions of interest often have electronic transition energies in the ultraviolet region. Recent standard method for generating such entangled photons is a chirped quasi-phase-matching method, however this method is not suitable for the generation of ultraviolet frequency-entangled photons because it requires down-conversion of a photon with a wavelength shorter than ultraviolet into an entangled photon pair...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28806697/photoelectron-spectra-and-biological-activity-of-cinnamic-acid-derivatives-revisited
#4
Igor Novak, Leo Klasinc, Sean P McGlynn
The electronic structures of several derivatives of cinnamic acid have been studied by UV photoelectron spectroscopy (UPS) and Green's function quantum chemical calculations. The spectra reveal the presence of dimers in the gas phase for p-coumaric and ferulic acids. The electronic structure analysis has been related to the biological properties of these compounds through the analysis of some structure-activity relationships (SAR).
August 10, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28802828/photolyase-dynamics-and-electron-transfer-mechanisms-of-dna-repair
#5
REVIEW
Meng Zhang, Lijuan Wang, Dongping Zhong
Photolyase, a flavoenzyme containing flavin adenine dinucleotide (FAD) molecule as a catalytic cofactor, repairs UV-induced DNA damage of cyclobutane pyrimidine dimer (CPD) and pyrimidine-pyrimidone (6-4) photoproduct using blue light. The FAD cofactor, conserved in the whole protein superfamily of photolyase/cryptochromes, adopts a unique folded configuration at the active site that plays a critical functional role in DNA repair. Here, we review our comprehensive characterization of the dynamics of flavin cofactor and its repair photocycles by different classes of photolyases on the most fundamental level...
August 9, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28801823/quantification-of-light-screening-by-anthocyanins-in-leaves-of-berberis-thunbergii
#6
Lars Nichelmann, Wolfgang Bilger
Up to 40% of incident light was screened in red Berberis leaves in vivo by anthocyanins, resulting also in up to 40% reduction of light-limited photosynthesis. The biological function of anthocyanins in leaves has been strongly discussed, but the hypothesis of a screening function is favored by most authors. For an evaluation of the function as photoprotective pigments, a quantification of their screening of the mesophyll is important. Here, chlorophyll fluorescence excitation of leaves of a red and a green variety of Berberis thunbergii was used to estimate the extent of screening by anthocyanins at 545 nm and over the whole photosynthetically active wavelength range...
August 11, 2017: Planta
https://www.readbyqxmd.com/read/28799001/switch-on-fluorescent-strategy-based-on-crystal-violet-functionalized-cdte-quantum-dots-for-detecting-l-cysteine-and-glutathione-in-water-and-urine
#7
Zhen Sheng, Ligang Chen
The concentration of L-cysteine (Cys) and glutathione (GSH) is closely related to the critical risk of various diseases. In our study, a new rapid method for the determination of Cys and GSH in water and urine samples has been developed using a fluorescent probe technique, which was based on crystal violet (CV)-functionalized CdTe quantum dots (QDs). The original QDs emitted fluorescence light, which was turned off upon adding CV. This conjugation of CV and QDs could be attributed to electrostatic interaction between COO(-) of mercaptopropionic acid (MPA) on the surface of QDs and N(+) of CV in aqueous solution...
August 10, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28798868/facile-synthesis-of-nano-sized-cufe2s3-morphology-and-diverse-functional-tuning-and-crystal-growth-mechanism-exploring
#8
Xiao Zhang, Huan Zhao, Yuda Zhu, You Yang, Dongli Jiang, Xiaoqin Chen, Jing Sun, Jiaoming Luo, Bing Cai, Hongsong Fan
Ternary chalcogenide compounds are such promising and have been used for much practical applications. As a sort of these compounds, cubanite (CuFe2S3) possess some unique properties which can be used in different fields. In our study, we developed a facile one pot synthesis of CuFe2S3 nanocrystals (NCs) at a low reaction temperature, and achieved a morphology and phase composition tuning of the NCs through changing a variety of precursors and surfactants, meanwhile improved their magnetism and optical properties...
August 2017: Regenerative Biomaterials
https://www.readbyqxmd.com/read/28791337/beam-profile-compensated-quantum-yield-measurements-of-upconverting-nanoparticles
#9
Monirehalsadat Mousavi, Björn Thomasson, Meng Li, Marco Kraft, Christian Würth, Ute Resch-Genger, Stefan Andersson-Engels
The quantum yield is a critically important parameter in the development of lanthanide-based upconverting nanoparticles (UCNPs) for use as novel contrast agents in biological imaging and optical reporters in assays. The present work focuses on the influence of the beam profile in measuring the quantum yield (ϕ) of nonscattering dispersions of nonlinear upconverting probes, by establishing a relation between ϕ and excitation light power density from a rate equation analysis. A resulting 60% correction in the measured ϕ due to the beam profile utilized for excitation underlines the significance of the beam profile in such measurements, and its impact when comparing results from different setups and groups across the world...
August 9, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28783304/post-polymerization-c-h-borylation-of-donor-acceptor-materials-gives-highly-efficient-solid-state-near-infrared-emitters-for-nir-oleds-and-effective-biological-imaging
#10
Daniel L Crossley, Laura Urbano, Robert Neumann, Struan Bourke, Jennifer Jones, Lea Ann Dailey, Mark A Green, Martin Humphries, Simon M King, Michael L Turner, Michael J Ingleson
Post-polymerization modification of the donor-acceptor polymer, poly(9,9-dioctylfluorene-alt-benzothiadiazole), PF8-BT by electrophilic C-H borylation is a simple method to introduce controllable quantities of near-infrared (NIR) emitting chromophore units into the backbone of a conjugated polymer. The highly stable borylated unit possesses a significantly lower LUMO energy than the pristine polymer resulting in a reduction in the band-gap of the polymer by up to 0.63 eV and a red shift in emission of more than 150 nm...
August 7, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28782953/revealing-the-local-proton-network-through-three-dimensional-13-c-1-h-double-quantum-1-h-single-quantum-and-1-h-double-quantum-13-c-1-h-single-quantum-correlations-fast-mas-solid-state-nmr-spectroscopy-at-natural-abundance
#11
Michal Malon, Manoj Kumar Pandey, Yusuke Nishiyama
1H double quantum (DQ)/1H single quantum (SQ) correlation solid-state NMR spectroscopy is widely used to obtain internuclear 1H-1H proximities, especially at fast magic angle spinning (MAS) rate > 60 kHz. However, 1H signals are not well-resolved due to intense 1H-1H homonuclear dipolar interactions even at the attainable maximum MAS frequencies of ~100 kHz to date and/or under 1H-1H homonuclear dipolar decoupling irradiations. Here we introduce novel three-dimensional (3D) experiments to resolve the 1H DQ/1H SQ correlation peaks using the additional 13C dimension...
August 7, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28782896/cesium-lead-halide-perovskite-quantum-dots-as-a-photoluminescence-probe-for-metal-ions
#12
Xuexi Sheng, Ying Liu, Yu Wang, Yafei Li, Xun Wang, Xinping Wang, Zhihui Dai, Jianchun Bao, Xiangxing Xu
Perovskite structured CsPbX3 (X = Cl, Br or I) quantum dots (QDs) have attracted great attention in the past few years for appealing application potentials in photovoltaic and optoelectronic devices. In this report, the CsPbX3 QDs are shown to perform as a new probe for metal ions with high sensitivity, high selectivity and instant response by the quenching or enhancing of the photoluminescence (PL). Through experimental and calculation efforts, the probing mechanisms are investigated. A wide probing window for Cu(2+) and Yb(3+) ions ranging from 2 × 10(-9) to 2 × 10(-6) m is exhibited for CsPbBr3 QDs...
August 7, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28777502/carbon-nanomaterials-in-biological-studies-and-biomedicine
#13
REVIEW
Nagappa L Teradal, Raz Jelinek
The "carbon nano-world" has made over the past few decades huge contributions in diverse scientific disciplines and technological advances. While dramatic advances have been widely publicized in using carbon nanomaterials such as fullerenes, carbon nanotubes, and graphene in materials sciences, nano-electronics, and photonics, their contributions to biology and biomedicine have been noteworthy as well. This Review focuses on the use of carbon nanotubes (CNTs), graphene, and carbon quantum dots [encompassing graphene quantum dots (GQDs) and carbon dots (C-dots)] in biologically oriented materials and applications...
August 4, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28773010/synthesis-of-au-np-mos%C3%A2-quantum-dots-core-shell-nanocomposites-for-sers-bio-analysis-and-label-free-bio-imaging
#14
Xixi Fei, Zhiming Liu, Yuqing Hou, Yi Li, Guangcun Yang, Chengkang Su, Zhen Wang, Huiqing Zhong, Zhengfei Zhuang, Zhouyi Guo
In this work, we report a facile method using MoS₂ quantum dots (QDs) as reducers to directly react with HAuCl₄ for the synthesis of Au nanoparticle@MoS₂ quantum dots (Au NP@MoS₂ QDs) core@shell nanocomposites with an ultrathin shell of ca. 1 nm. The prepared Au NP@MoS₂ QDs reveal high surface enhanced Raman scattering (SERS) performance regarding sensitivity as well as the satisfactory SERS reproducibility and stability. The limit of detection of the hybrids for crystal violet can reach 0.5 nM with a reasonable linear response range from 0...
June 13, 2017: Materials
https://www.readbyqxmd.com/read/28770907/two-photon-absorption-in-a-series-of-2-6-disubstituted-bodipy-dyes
#15
Leonardo W T Barros, Thiago A S Cardoso, Angela Bihlmeier, Danny Wagner, Dominik K Kölmel, Anna Hörner, Stefan Bräse, Carlos H Brito Cruz, Lazaro A Padilha
We report on the two-photon absorption spectra of a series of 2,6-disubstituted BODIPY dyes. Depending on the substituents, we observe increasing two-photon absorption cross sections with values up to 350 GM compared to 70 GM in the unsubstituted dye. Quantum chemical calculations are performed to assign the absorption bands and to understand the factors controlling the size of the two-photon absorption cross section. Both the maximum of the two-photon absorption band as well as the red-shift of the whole spectrum correlate with the ability of the substituents to extend the π-electron system of the dye...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28768099/a-multi-dimensional-b-spline-method-for-accurate-modeling-sugar-puckering-in-qm-mm-simulations
#16
Ming Huang, Thakshila Dissanayake, Erich Kuechler, Brian K Radak, Tai-Sung Lee, Timothy J Giese, Darrin M York
The computational efficiency of approximate quantum mechanical methods allows their use for the construction of multi-dimensional reaction free energy profiles. It has recently been demonstrated that quantum models based on the neglect of diatomic differential overlap (NNDO) approximation have difficulty modeling deoxyribose and ribose sugar ring puckers, and thus limit their predictive value in the study of RNA and DNA systems. A method has been introduced in our previous work to improve the description of the sugar puckering conformational landscape that uses a multi-dimensional B-spline correction map (BMAP correction) for systems involving intrinsically coupled the torsion angles...
August 2, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28765875/quantum-dot-pmhc-multimers-vs-phycoerythrin-pmhc-tetramers-for-identification-of-hla-a-0201-restricted-phbv-core-antigen18-27-specific-t-cells
#17
Jianmeng Zhu, Yong Huang, Jing Su, Jian He, Yating Yu, Yongxiang Zhao, Xiaoling Lu
Detection of human leukocyte antigens-A2-restricted p-hepatitis B virus (HBV) core antigen‑specific cytotoxic T lymphocytes (CTLs) is important in the study of HBV immunopathogenesis and vaccine design. Currently, major histocompatibility complex (MHC) class I/peptide‑(p) MHCI tetramers are considered the optimal tools to detect antigen‑specific CTLs. However, the MHC‑tetramer technique also has certain drawbacks and is under continuous development. The quantum dot (QD) bioconjugates nanotechnology with its unique inorganic‑biological properties has been developing fast...
August 1, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28759855/computational-investigations-of-trans%C3%A2-platinum-ii-oxime-complexes-used-as-anticancer-drug
#18
Koray Sayin, Duran Karakaş
Some platinum oxime complexes are optimized at HF/CEP-31G level which has been reported as the best level for these type complexes in the gas phase. IR spectrum is calculated and the new scale factor is derived. NMR spectrum is calculated at the same level of theory and examined in detail. Quantum chemical parameters which have been mainly used are investigated and their formulas are given in detail. Additionally, selected quantum chemical parameters of studied complexes are calculated. New theoretical IC50% formulas are derived and biological activity rankings of mentioned complexes are investigated...
July 21, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28756257/quantum-mechanical-and-spectroscopic-ft-ir-ft-raman-study-nbo-analysis-homo-lumo-first-order-hyperpolarizability-and-molecular-docking-study-of-methyl-3r-3-2-methylphenoxy-3-phenylpropyl-amine-by-density-functional-method
#19
Tintu K Kuruvilla, Johanan Christian Prasana, S Muthu, Jacob George, Sheril Ann Mathew
Quantum chemical techniques such as density functional theory (DFT) have become a powerful tool in the investigation of the molecular structure and vibrational spectrum and are finding increasing use in application related to biological systems. The Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) techniques are employed to characterize the title compound. The vibrational frequencies were obtained by DFT/B3LYP calculations with 6-31G(d,p) and 6-311++G(d,p) as basis sets. The geometry of the title compound was optimized...
July 21, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28749132/universal-ratiometric-photoelectrochemical-bioassay-with-target-nucleotide-transduction-amplification-and-electron-transfer-tunneling-distance-regulation-strategies-for-ultrasensitive-determination-of-microrna-in-cells
#20
Ying-Ning Zheng, Wen-Bin Liang, Cheng-Yi Xiong, Ying Zhuo, Ya-Qin Chai, Ruo Yuan
A universal ratiometric photoelectrochemical (PEC) bioassay, which could be readily expanded for ultrasensitive determination of various targets in complex biological matrixes, was established by coupling a target-nucleotide transduction-amplification with DNA nanomachine mediated electron-transfer tunneling distance regulation strategies. With the help of target-nucleotide transduction-amplification strategy, the one input target signal could be transducted to corresponding multiple output DNA signals by nucleotide specific recognition technology, simultaneously leading to an efficient signal amplification for target...
August 11, 2017: Analytical Chemistry
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