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Quantum biology

Huaping Peng, Danwei Lin, Pan Liu, Yanhong Wu, Shanhong Li, Yun Lei, Wei Chen, Yuanzhong Chen, Xinhua Lin, Xinghua Xia, Ailin Liu
This report outlines a rapid and highly sensitive colorimetric sensing platform based on a novel water-soluble WOx quantum dots (QDs) as enzymatic mimics. The WOx QDs, synthesized by a green hydrothermal method, were proven to possess excellent intrinsic peroxidase-like activity. The peroxidase substrate, 2, 2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) could be catalyzed oxidation by WOx QDs quickly in the present of H2O2 to form a green color. Due to its excellent properties such as excellent water-solublity, good biocompatibility, easy preparation, and high stability, the proposed system showed typical Michaelis-Menten kinetics and high affinity for ABTS and H2O2, indicating WOx QDs can be used as satisfactory peroxidase mimics...
November 1, 2017: Analytica Chimica Acta
Przemysław Krawczyk, Beata Jędrzejewska, Piotr Cysewski, Tomasz Janek
In this study, a new oxazolone derivative 4-{N,N-bis[2-phenyl-4-benzylidene-1,3-oxazol-5(4H)-one]amino}benzaldehyde (PB3) was synthesized and investigated as a fluorescent dye. The spectroscopic properties in different solvents were thoroughly studied. The experimental data were supported by quantum-chemical calculations using density functional theory. Measurements and theoretical calculations showed that the PB3 dye is characterized by non-monotonic solvatochromism, a strongly polar charge transfer excited state, a large Stokes' shift, a high fluorescence quantum yield and a high fluorescence lifetime...
October 18, 2017: Organic & Biomolecular Chemistry
Souichi Sakamoto, Yoshitaka Tanimura
We theoretically investigate an exciton-coupled electron transfer (XCET) process that is conversion of an exciton into a charge transfer state. This conversion happens in an exciton transfer (XT) process, and the electron moves away in an electron transfer(ET) process in multiple environments (baths). This XCET process plays an essential role in the harvesting of solar energy in biological and photovoltaic materials. We develop a practical theoretical model to study the efficiency of XCET process that occurs either in consecutive or concerted processes under the influence of non-Markovian baths...
October 17, 2017: Journal of Physical Chemistry Letters
Tomáš Slanina, Pradeep Shrestha, Eduardo Palao, Dnyaneshwar Kand, Julie A Peterson, Andrew S Dutton, Naama Rubinstein, Roy Weinstain, Arthur H Winter, Petr Klán
A detailed investigation of the photophysical parameters and photochemical reactivity of meso-methyl BODIPY photoremovable protecting groups was accomplished through systematic variation of the leaving group (LG) and core substituents as well as substitutions at boron. Efficiencies of the LG release were evaluated using both steady-state and transient absorption spectroscopies as well as computational analyses to identify the optimal structural features. We find that the quantum yields for photorelease with this photocage are highly sensitive to substituent effects...
October 17, 2017: Journal of the American Chemical Society
Kamal Fahmy Mohamed Atta, Tamer Mohamed Ibrahim, Omaima Osman Mahmoud Farahat, Tareq Qasem Al-Shargabi, Mohamed Gaber Marei, Adnan Ahmed Bekhit, El Sayed Helmy El Ashry
AIM: A new series of pyrazolo[1,5-c]pyrimidines were synthesized by different hybridization strategies. METHODOLOGY: All structures were confirmed by IR, (1)H, (13)C, (1)H-(13)C heteronuclear multiple-quantum correlation (HMQC) spectra and microanalysis. They were evaluated for their in vitro antileishmanial activity against miltefosine and amphotericin B deoxycholate as reference drugs. RESULTS: The most active compounds 2a and 9a demonstrated superior potencies to miltefosine by ten- and six-fold, respectively, for the promastigote form, and by 5...
October 13, 2017: Future Medicinal Chemistry
Stepan Stehlik, Marian Varga, Pavla Štenclová, Lukáš Ondič, Martin Ledinsky, Jiří Pangrác, Ondrej Vanek, Jan Lipov, Alexander Kromka, Bohuslav Rezek
Color centers in diamond have shown excellent potential for applications in quantum information processing, photonics, and biology. Here we report chemical vapor deposition (CVD) growth of as thin as 5-6 nm nanocrystalline diamond (NCD) films with photoluminescence (PL) from silicon-vacancy (SiV) centers at 739 nm. Instead of conventional 4-6 nm detonation nanodiamonds (DNDs) we prepared and employed hydrogenated 2 nm DNDs (zeta potential +36 mV) to form extremely dense (~ 1.3 × 1013 cm-2), thin (2 ± 1 nm) and smooth (RMS roughness < 0...
October 13, 2017: ACS Applied Materials & Interfaces
Varun K A Sreenivasan, Wan Aizuddin W Razali, Kai Zhang, Rashmi R Pillai, Avishkar Saini, Denitza Denkova, Marina Santiago, Hannah Brown, Jeremy Thompson, Mark Connor, Ewa M Goldys, Andrei V Zvyagin
At the forefront of development of fluorescent probes for biological imaging applications are enhancements aimed at increasing their brightness, contrast, and photostability, especially towards demanding applications of single molecule detection. In comparison with existing probes, nanorubies exhibit unlimited photostability and a long emission lifetime (3.7 ms), which enable continuous imaging at single-particle sensitivity in highly scattering and fluorescent biological specimens. However, their wide application as fluorescence probes has so far been hindered by the absence of facile methods for scaled-up high volume production and molecularly-specific targeting...
October 12, 2017: ACS Applied Materials & Interfaces
Xin Shang, Rui Lai, Xi Song, Hui Li, Wei Niu, Jiantao Guo
The 1,3-dipolar cycloaddition reaction between an alkene and a tetrazole represents one elegant and rare example of fluorophore-forming bioorthogonal chemistry. This is an attractive reaction for imaging applications in live cells that requires less intensive washing steps and/or needs spatiotemporal resolutions. In the present work, as an effort to improve the fluorogenic property of the alkene-tetrazole reaction, an aromatic alkene (styrene) was investigated as the dipolarophile. Over 30-fold improvement in quantum yield of the reaction product was achieved in aqueous solution...
October 12, 2017: Bioconjugate Chemistry
Reza Sahraei, Ehsan Soheyli, Zahra Faraji, Mohammad Soleiman-Beigi
We report here a one pot, mild and low cost aqueous-based synthetic route for preparation of colloidally stable and highly luminescent dual-doped Ag,Ni:ZnCdS/ZnS core/shell quantum dots (QDs). The pure dopant emission of the Ni-doped core/shell quantum dots was found to be highly effected at the presence of second dopant ion (Ag+). Results showed that the PL emission intensity increases while its peak position experiences an obvious blue shift with increasing the content of Ag+ ions. Regarding the optical observations, we simply provide a scheme for absorption-recombination processes of the carriers through impurity centers...
October 11, 2017: Nanotechnology
Paula Quintero-Ronderos, Eric Mercier, Michiko Fukuda, Ronald González, Carlos Fernando Suárez, Manuel Alfonso Patarroyo, Daniel Vaiman, Jean-Christophe Gris, Paul Laissue
Recurrent pregnancy loss is a frequently occurring human infertility-related disease affecting ~1% of women. It has been estimated that the cause remains unexplained in >50% cases which strongly suggests that genetic factors may contribute towards the phenotype. Concerning its molecular aetiology numerous studies have had limited success in identifying the disease's genetic causes. This might have been due to the fact that hundreds of genes are involved in each physiological step necessary for guaranteeing reproductive success in mammals...
2017: PloS One
Yi-Ting Chen, Arati G Kolhatkar, Oussama Zenasni, Shoujun Xu, T Randall Lee
Magnetic particles are widely used as signal labels in a variety of biological sensing applications, such as molecular detection and related strategies that rely on ligand-receptor binding. In this review, we explore the fundamental concepts involved in designing magnetic particles for biosensing applications and the techniques used to detect them. First, we briefly describe the magnetic properties that are important for bio-sensing applications and highlight the associated key parameters (such as the starting materials, size, functionalization methods, and bio-conjugation strategies)...
October 10, 2017: Sensors
Sajan Singh, Pratick Samanta, Rajiv Srivastava, Andriy Horechyy, Uta Reuter, Manfred Stamm, Hsin-Lung Chen, Bhanu Nandan
We investigate the self-assembly of a cylinder-forming polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) mixed with trioctylphosphine oxide (TOPO) capped cadmium selenide (CdSe) quantum dots (QDs). The QDs were found to be enthalpically compatible with the P4VP chains via ligand displacement of TOPO from the QD surface. However, the QDs were found to localize preferentially at the PS/P4VP interphase plausibly to gain translational entropy in order to further lower the energetics of the self-assembled structure...
October 18, 2017: Physical Chemistry Chemical Physics: PCCP
Guangfu Feng, Chao Luo, Haibo Yi, Lin Yuan, Bin Lin, Xingyu Luo, Xiaoxiao Hu, Honghui Wang, Chunyang Lei, Zhou Nie, Shouzhuo Yao
Red fluorescent proteins (RFPs) have emerged as valuable biological markers for biomolecule imaging in living systems. Developing artificial fluorogenic systems that mimic RFPs remains an unmet challenge. Here, we describe the design and synthesis of six new chromophores analogous to the chromophores in RFPs. We demonstrate, for the first time, that encapsulating RFP chromophore analogues in canonical DNA G-quadruplexes (G4) can activate bright fluorescence spanning red and far-red spectral regions (Em = 583-668 nm) that nearly match the entire RFP palette...
September 13, 2017: Nucleic Acids Research
Hamish G Hiscock, Henrik Mouritsen, David E Manolopoulos, P J Hore
The radical-pair mechanism has been put forward as the basis of the magnetic compass sense of migratory birds. Some of the strongest supporting evidence has come from behavioral experiments in which birds exposed to weak time-dependent magnetic fields lose their ability to orient in the geomagnetic field. However, conflicting results and skepticism about the requirement for abnormally long quantum coherence lifetimes have cast a shroud of uncertainty over these potentially pivotal studies. Using a recently developed computational approach, we explore the effects of various radiofrequency magnetic fields on biologically plausible radicals within the theoretical framework of radical-pair magnetoreception...
October 3, 2017: Biophysical Journal
Paulo R Bueno, Flávio C Bedatty Fernandes, Jason J Davis
The application of nanoscale capacitance as a transduction of molecular recognition relevant to molecular diagnostics is demonstrated. The energy-related signal relates directly to the electron occupation of quantized states present in readily fabricated molecular junctions such as those presented by redox switchable self-assembled molecular monolayers, reduced graphene oxide or redox-active graphene composite films, assembled on standard metallic or micro-fabricated electrodes. Sensor design is thus based on the response of a confined and resolved electronic density of states to target binding and the associated change in interfacial chemical potential...
October 19, 2017: Nanoscale
Yi Zou, Fang Wang, Yan Wang, Qirui Sun, Yue Hu, Yuezhen Li, Wen Liu, Wenjie Guo, Zhangjian Huang, Yihua Zhang, Qiang Xu, Yisheng Lai
Indoleamine-2,3-dioxygenase-1 (IDO1) is an attractive target for cancer immunotherapy. Herein, a series of novel imidazoleisoindole derivatives were prepared and evaluated for their ability to inhibit IDO1. Among these, derivative 11r was the most active compound with nanomolar potency in the Hela cell-based assay, while showed negligible cellular toxicity. UV-visible spectra study demonstrated that compounds 11p and 11r bound to IDO1 and coordinated with the heme iron. Furthermore, they could significantly promote T cell proliferation, increase IFN-γ production, and reduce the numbers of Foxp3(+) regulatory T cells...
September 18, 2017: European Journal of Medicinal Chemistry
Meghna A Manae, Anirban Hazra
Substituted thymines, where oxygen is replaced by sulfur or selenium, affect a variety of functions in biological systems and are prospective phototherapeutic agents. In this study, we show that an interplay between two types of delocalization, one due to conjugation and the other owing to the varying size of the substituted atom, leads to distinct absorption spectra and electrophilic sites in substituted thymines. This result is supported by ab initio quantum chemical calculations and a simple particle-in-a-box model...
October 11, 2017: Journal of Physical Chemistry. A
Minoru Yamaji, Shin-Ichiro Kato, Kazuhiro Tomonari, Michitaka Mamiya, Kenta Goto, Hideki Okamoto, Yosuke Nakamura, Fumito Tani
Small molecules having intense luminescence properties are required to promote biological and organic material applications. We prepared five types of benzamides having pyridine, pyridazine, pyrazine, and pyrimidine rings and successfully converted them into three types of the difluoroboronated complexes, Py@BAs, as novel blue fluorophores. Py@BA having a pyridine moiety (2-Py@BA) showed no fluorescence in solution, whereas Py@BAs of pyridazine and pyrazine moieties (2,3-Py@BA and 2,5-Py@BA, respectively) emitted blue fluorescence with quantum yields of ca...
September 26, 2017: Inorganic Chemistry
Sarah Schmidt, Isabella Tavernaro, Christian Cavelius, Eva Weber, Alexander Kümper, Carmen Schmitz, Jana Fleddermann, Annette Kraegeloh
In this study, a novel approach for preparation of green fluorescent protein (GFP)-doped silica nanoparticles with a narrow size distribution is presented. GFP was chosen as a model protein due to its autofluorescence. Protein-doped nanoparticles have a high application potential in the field of intracellular protein delivery. In addition, fluorescently labelled particles can be used for bioimaging. The size of these protein-doped nanoparticles was adjusted from 15 to 35 nm using a multistep synthesis process, comprising the particle core synthesis followed by shell regrowth steps...
September 25, 2017: Nanoscale Research Letters
K N Houk, Fang Liu
Computational chemistry and biochemistry began with Isaac Newton's classical mechanics in the 17th century and the establishment of quantum mechanics in the 1920s. Enabled by extraordinary advances in computers, in the last half century, this field has become a robust partner with experiment. The challenges facing computational chemists and biochemists, the Holy Grails of the field, are described. These include the development of a highly accurate density functional, ideally one that has universal chemical accuracy, and accurate polarizable force fields, as well as methods to handle efficiently the massive number of computations that must be performed for molecular dynamics and for the computation of flexible systems such as proteins...
March 21, 2017: Accounts of Chemical Research
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