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Quantum biology

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https://www.readbyqxmd.com/read/29457613/on-the-photocatalytic-cycle-of-water-splitting-with-small-manganese-oxides-and-the-roles-of-water-clusters-as-direct-sources-of-oxygen-molecules
#1
Kentaro Yamamoto, Kazuo Takatsuka
We theoretically studied the chemical principles behind the photodynamics of water splitting: 2H2 O + 4hν + M → 4H+ + 4e- + O2 + M. To comprehend this simple looking but very complicated reaction, the mechanisms of at least three crucial phenomena, among others, need to be clarified, each of which is supposed to constitute the foundation of chemistry: (i) charge separation (4H+ + 4e- ), (ii) the catalytic cycle for essentially the same reactions to be repeated by each of four photon absorptions with a catalyst M, and (iii) the generation of oxygen molecules of spin triplet...
February 19, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29453547/using-of-quantum-dots-in-biology-and-medicine
#2
Svetlana Pleskova, Elza Mikheeva, Ekaterina Gornostaeva
Quantum dots are nanoparticles, which due to their unique physical and chemical (first of all optical) properties, are promising in biology and medicine. There are many ways for quantum dots synthesis, both in the form of nanoislands self-forming on the surfaces, which can be used as single-photon emitters in electronics for storing information, and in the form of colloidal quantum dots for diagnostic and therapeutic purposes in living systems. The paper describes the main methods of quantum dots synthesis and summarizes medical and biological ways of their use...
2018: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/29453141/dft-td-dft-calculations-spectroscopic-characterizations-ftir-nmr-uv-vis-molecular-docking-and-enzyme-inhibition-study-of-7-benzoyloxycoumarin
#3
Mahboob Alam, Mohammad Jane Alam, Shaista Azaz, Mehtab Parveen, Soonheum Park, Shabbir Ahmad
The quantum chemical study, spectroscopic characterization and biological activity of the pharmaceutically active 7-benzoyloxycoumarin (2) molecule have been presented. Potential energy surface (PES) scanning has been performed to search for the most stable molecular geometry of the present compound. The stable geometry in the ground state, IR, UV-Vis absorption and NMR ( 13 C, 1 H) spectra of the title compound were theoretically obtained and compared with the experimental one. Various theoretical molecular parameters like molecular energy, atomic charges, dipole moment, thermodynamic parameters, donor-acceptor natural bond orbital (NBO) hyperconjugative interaction energies, frontier molecular orbitals energies, HOMO-LUMO gap, molecular electrostatic potential, chemical reactivity descriptors, molecular polarizability and non-linear optical (NLO) properties are presented...
February 8, 2018: Computational Biology and Chemistry
https://www.readbyqxmd.com/read/29451567/stable-small-specific-low-valency-quantum-dots-for-single-molecule-imaging
#4
Jungmin Lee, Xinyi Feng, Ou Chen, Moungi G Bawendi, Jun Huang
We have developed a strategy for synthesizing immediately activable, water-soluble, compact (∼10-12 nm hydrodynamic diameter) quantum dots with a small number of stable and controllable conjugation handles for long distance delivery and subsequent biomolecule conjugation. Upon covalent conjugation with engineered monovalent streptavidin, the sample results in a population consisting of low-valency quantum dots. Alternatively, we have synthesized quantum dots with a small number of biotin molecules that can self-assemble with engineered divalent streptavidin via high-affinity biotin-streptavidin interactions...
February 16, 2018: Nanoscale
https://www.readbyqxmd.com/read/29448649/a-self-assembly-fluorescence-sensing-platform-for-glutathione-detection-based-on-eco-friendly-quantum-dots-and-mno%C3%A2-nanosheets
#5
Qiyong Cai, Lin Zhang, Xin Geng, Jia Ge, Zhaohui Li
Glutathione (GSH), a thiol-containing tripeptide, has a pivotal role in maintaining the normally physiological environment in biology. Here, we report a novel self-assembly fluorescence resonance energy transfer (FRET) sensing platform for GSH detection by using the environment-friendly Cu:Zn-In-S/ZnS quantum dots (QDs) and MnO2 nanosheets. In this assay, fluorescence of Cu:Zn- In-S/ZnS QDs could be quenched by MnO2 nanosheets based on FRET. Upon the addition of GSH, MnO2 nanosheets were reduced into Mn2+ ions because of the rapid redox reaction, and consequently the fluorescence of QDs was recovered...
March 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29448376/matrix-product-algorithm-for-stochastic-dynamics-on-networks-applied-to-nonequilibrium-glauber-dynamics
#6
Thomas Barthel, Caterina De Bacco, Silvio Franz
We introduce and apply an efficient method for the precise simulation of stochastic dynamical processes on locally treelike graphs. Networks with cycles are treated in the framework of the cavity method. Such models correspond, for example, to spin-glass systems, Boolean networks, neural networks, or other technological, biological, and social networks. Building upon ideas from quantum many-body theory, our approach is based on a matrix product approximation of the so-called edge messages-conditional probabilities of vertex variable trajectories...
January 2018: Physical Review. E
https://www.readbyqxmd.com/read/29444056/high-resolution-multiphoton-microscopy-with-a-low-power-continuous-wave-laser-pump
#7
Xiang-Dong Chen, Shen Li, Bo Du, Yang Dong, Ze-Hao Wang, Guang-Can Guo, Fang-Wen Sun
Multiphoton microscopy (MPM) has been widely used for three-dimensional biological imaging. Here, based on the photon-induced charge state conversion process, we demonstrated a low-power high-resolution MPM with a nitrogen vacancy (NV) center in diamond. Continuous wave green and orange lasers were used to pump and detect the two-photon charge state conversion, respectively. The power of the laser for multiphoton excitation was 40 μW. Both the axial and lateral resolutions were improved approximately 1.5 times compared with confocal microscopy...
February 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29442930/fluorescence-stability-of-mercaptopropionic-acid-capped-cadmium-telluride-quantum-dots-in-various-biochemical-buffers
#8
Vivek Borse, Adisha Kashikar, Rohit Srivastava
Quantum dots are the semiconductor nanocrystals having unique optical and electronic properties. Quantum dots are category of fluorescent labels utilized for biological tagging, biosensing, bioassays, bioimaging and in vivo imaging as they exhibit very small size, signal brightness, photostability, tuning of light emission range, longer photoluminescence decay time as compared to organic dyes. In this work, we have synthesized and characterized mercaptopropionic acid capped cadmium telluride quantum dots (MPA-CdTe QDs) using hydrothermal method...
April 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29442619/one-step-hydrothermal-approach-to-synthesis-carbon-dots-from-d-sorbitol-for-detection-of-iron-iii-and-cell-imaging
#9
Junqiu Zhang, Juping Yan, Yingte Wang, Yong Zhang
A facile and economic approach to synthesis highly fluorescence carbon dots (CDs) via one-step hydrothermal treatment of D-sorbitol was presented. The as-synthesized CDs were characterized by good water solubility, well monodispersion, and excellent biocompatibility. Spherical CDs had a particle size about 5 nm and exhibited a quantum yield of 8.85% at excitation wavelength of 360 nm. In addition, the CDs can serve as fluorescent probe for sensitive and selective detection of Fe3+ ions with the detection limit of 1...
July 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29439575/density-dependent-formulation-of-dispersion-repulsion-interactions-in-hybrid-qm-mm-models
#10
Carles Curutchet, Lorenzo Cupellini, Jacob Kongsted, Stefano Corni, Luca Frediani, Arnfinn Hykkerud Steindal, Ciro Achille Guido, Giovanni Scalmani, Benedetta Mennucci
Mixed QM/MM models are widely used to explore the structure, reactivity and electronic properties of complex chemical systems. Whereas such models typically include electrostatics, and potentially polarization in so-called electrostatic and polarizable embedding approaches, respectively, non-electrostatic dispersion and repulsion interactions are instead commonly described through classical potentials despite their quantum mechanical origin. Here we present an extension of the Tkatchenko-Scheffler semiempirical van der Waals (vdWTS) scheme aimed at describing dispersion and repulsion interactions between quantum and classical regions within a QM/MM polarizable embedding framework...
February 13, 2018: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/29438102/gold-carbon-dots-for-the-intracellular-imaging-of-cancer-derived-exosomes
#11
Xiaoyue Jiang, Shenfei Zong, Chen Chen, Yizhi Zhang, Zhuyuan Wang, Yiping Cui
As a novel fluorescent nanomaterial, gold-carbon quantum dots (GCDs) possess high biocompatibility and can be easily synthesized by a microwave-assisted method. Owing to their small sizes and unique optical properties, GCDs can be applied to imaging of biological targets, such as cells, exosomes and other organelles. In this study, GCDs were used for fluorescence imaging of exosomes. Tumor-specific antibodies are attached to the GCDs, forming exosome specific nanoprobes. The nanoprobes can label exosomes via immuno-reactions and thus facilitate fluorescent imaging of exosomes...
February 13, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29432899/non-canonical-dna-structures-comparative-quantum-mechanical-study
#12
Stanislav S Bachurin, Mikhail E Kletskii, Oleg N Burov, Sergey V Kurbatov
A study of relative thermodynamic stability of non-canonical DNA structures (triplexes, G-quadruplexes, i-motifs) for the first time was conducted on the basis of quantum chemical DFT/B3LYP/6-31++G (d) calculations. Results of the calculations completely reproduce the experimental data on stability of G-quadruplexes comparatively Watson-Crick B-DNA. It was discovered that combinations of non-canonical DNA structures were energetically more favorable than separated nitrogenous bases. Supramolecular complexes of the non-canonical DNA structures (NSs) can be considered as a biological drug targets in gene regulation (for example in tumor therapy), in contrast to previous works, where NSs were studied independently...
February 8, 2018: Biophysical Chemistry
https://www.readbyqxmd.com/read/29432781/pleiotropy-the-physiologic-basis-for-biologic-fields
#13
REVIEW
John S Torday
Biologic organisms act like fields. Hypothetically, pleiotropy results from the systematic re-purposing of genes over the course of the evolutionary history of the organism as pre-adaptations or exaptations. Mechanistically, pleiotropic genes are selected for during the process of evolution with reference to the First Principles of Physiology (FPP). Under stress conditions, pleiotropic genes will act as a functional network to cohesively maintain allostasis. There are strong homologies between Quantum Mechanics and the FPP...
February 9, 2018: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/29424521/deep-eutectic-solvent-assisted-preparation-of-nitrogen-chloride-doped-carbon-dots-for-intracellular-biological-sensing-and-live-cell-imaging
#14
Ning Wang, An-Qi Zheng, Xun Liu, Junjie Chen, Ting Yang, Ming-Li Chen, Jian-Hua Wang
A novel approach for the preparation of dual-functional carbon dots, i.e., nitrogen and chloride doped carbon dots, shortly as N/Cl-CDs, is developed with the assistance of a choline chloride-glycerine deep eutectic solvent (DES). The carbon source is provided by urea and the DES serves as a solvent for controlling the preparation of CDs in the absence of water. The dual-element doped carbon dots are oxygen-rich with hydroxyl and amine groups. They exhibit an average particle size of ca. 3.88 nm, and give rise to strong and pH-sensitive fluorescent emission at λex/λem=340/430 nm with a quantum yield of 16...
February 9, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29424250/graphene-based-nanocomposites-synthesis-and-their-theranostic-applications
#15
Asadullah Madni, Sobia Noreen, Irsah Maqbool, Faizza Rehman, Amna Batool, Prince Muhammad Kashif, Mubashar Rehman, Nayab Tahir, Muhammad Imran Khan
Graphene, the mother of all carbon materials has unlocked a new era of biomedical nanomaterials due to its exceptional biocompatibility, physicochemical and mechanical properties. It is a single atom thick, nanosized, 2-dimensional structure and provides high surface area with adjustable surface chemistry to form hybrids. The present article provides a comprehensive review of ever-expanding application of graphene nanomaterials with different inorganic and organic materials in drug delivery and theranostics...
February 9, 2018: Journal of Drug Targeting
https://www.readbyqxmd.com/read/29423487/the-emergence-of-aqueous-chemiluminescence-new-promising-class-of-phenoxy-1-2-dioxetane-luminophores
#16
Samer Gnaim, Ori Green, Doron Shabat
The majority of known chemiluminescent compounds produce light through oxidation-dependent mechanisms. The unique notion of triggering chemiluminescence by a chemical reaction other than oxidation was first introduced by Schaap in 1987 with the development of chemically and enzymatically activated phenoxy-dioxetanes. Such dioxetanes are distinctive among chemiluminescent molecules since the oxidized high-energy species, the dioxetane, is stable for years at room temperature. Light emission is selectively activated by deprotection of the phenol-protecting group...
February 9, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29422126/highly-selective-and-sensitive-fluorescence-sensing-of-nanomolar-zn2-ions-in-aqueous-medium-using-calix-4-arene-passivated-carbon-quantum-dots-based-on-fluorescence-enhancement-real-time-monitoring-and-intracellular-investigation
#17
Harpreet Kaur, Pushap Raj, Hemant Sharma, Meenakshi Verma, Narinder Singh, Navneet Kaur
Carbon Quantum Dots (CDs) owing to its unique photophysical properties have attracted immense consideration of the researchers in last decade to explore its applications in the fields of bio-imaging and sensing. In the present work, we have developed a novel CDs functionalized with Calix[4]arene derivative by hydrothermal route to detect biologically pertinent Zn2+ ions. Surface modification of CDs enhances fluorescence efficiency apart from introducing active surface sites broadening its sensor capabilities...
June 7, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29420948/double-labelling-of-intracellular-mitochondria-and-nucleolus-using-thiophene-pyridium-salt-with-high-quantum-yield-as-biosensor-and-its-application-in-stimulated-emission-depletion-nanoscopy
#18
Xiaohe Tian, Hui Wang, Qiong Zhang, Mingzhu Zhang, Yingzhong Zhu, Yan Chen, Jieying Wu, Yupeng Tian
Probe for dual-site target distinct subcellular compartments from cytosol and nucleus is an attractive approach, however, which was scarcely reported. Herein, a series of small-molecular thiophene pyridium salt derivatives (MitoNuc1-4) possessing water-soluble, high quantum yield and two-photon activity were rationally designed, and their structures were crystallographic confirmed. Systematic photophysical and biological imaging property investigations were carried out for them. It was found that MitoNuc1-4 exhibit two-photon absorption properties in the near infrared region, and MitoNuc1 has membrane permeability and cationic nature, rendering it to be double labelling of mitochondria and nucleolus in living cells with superb photo-stability and non-invasiveness...
May 30, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29420080/calcium-ion-cyclotron-resonance-in-dissipative-water-structures
#19
Alexander Pazur
Weak magnetic and electromagnetic fields affect physiological processes in animals, plants, and microorganisms. Ion cyclotron resonance (ICR) is discussed as one of the sensitive mechanisms, which enable perception of the geomagnetic field and its orientation. Numerous biological effects are observed involving several small ions, showing windows of predicted frequencies and intensities. The pioneering work of Guiliano Preparata and Emilio Del Giudice using quantum electrodynamics showed that spontaneously originating coherent regions in water facilitate ICR effects at incoherent water phase boundaries...
February 8, 2018: Electromagnetic Biology and Medicine
https://www.readbyqxmd.com/read/29419299/acid-dissociation-equilibrium-and-singlet-molecular-oxygen-quantum-yield-of-acetylated-6-8-dithioguanosine-in-aqueous-buffer-solution
#20
Shoma Miyata, Mina Hoshino, Tasuku Isozaki, Takeshi Yamada, Hideyuki Sugimura, Yao Zhong Xu, Tadashi Suzuki
2',3',5'-Tri-O-acetyl-6,8-dithioguanosine (taDTGuo) is a modified nucleoside of drug 6-thioguanine and further developed as a potential photochemotherapeutic agent due to its desirable properties of photosensitivity to UVA light and singlet molecular oxygen generation. The photochemical characteristics of taDTGuo under biological conditions (namely in aqueous solution) were intensively investigated by the steady-state absorption and emission, time-resolved near-infrared emission measurements, and quantum chemical calculations...
February 8, 2018: Journal of Physical Chemistry. B
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