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ACS Central Science

Chang Liu, J C Yves Le Blanc, Bradley B Schneider, Jefry Shields, James J Federico, Hui Zhang, Justin G Stroh, Gregory W Kauffman, Daniel W Kung, Michael Shapiro, Christian Ieritano, Evan Shepherdson, Mitch Verbuyst, Luke Melo, Moaraj Hasan, Dalia Naser, John S Janiszewski, W Scott Hopkins, J Larry Campbell
[This corrects the article DOI: 10.1021/acscentsci.6b00297.].
April 26, 2017: ACS Central Science
Ori Green, Tal Eilon, Nir Hananya, Sara Gutkin, Christoph R Bauer, Doron Shabat
Chemiluminescence probes are considered to be among the most sensitive diagnostic tools that provide high signal-to-noise ratio for various applications such as DNA detection and immunoassays. We have developed a new molecular methodology to design and foresee light-emission properties of turn-ON chemiluminescence dioxetane probes suitable for use under physiological conditions. The methodology is based on incorporation of a substituent on the benzoate species obtained during the chemiexcitation pathway of Schaap's adamantylidene-dioxetane probe...
April 26, 2017: ACS Central Science
Alessondra T Speidel, Daniel J Stuckey, Lesley W Chow, Laurence H Jackson, Michela Noseda, Marta Abreu Paiva, Michael D Schneider, Molly M Stevens
Retention and survival of transplanted cells are major limitations to the efficacy of regenerative medicine, with short-term paracrine signals being the principal mechanism underlying current cell therapies for heart repair. Consequently, even improvements in short-term durability may have a potential impact on cardiac cell grafting. We have developed a multimodal hydrogel-based platform comprised of a poly(ethylene glycol) network cross-linked with bioactive peptides functionalized with Gd(III) in order to monitor the localization and retention of the hydrogel in vivo by magnetic resonance imaging...
April 26, 2017: ACS Central Science
Roger R Nani, Alexander P Gorka, Tadanobu Nagaya, Tsuyoshi Yamamoto, Joseph Ivanic, Hisataka Kobayashi, Martin J Schnermann
Near-IR photocaging groups based on the heptamethine cyanine scaffold present the opportunity to visualize and then treat diseased tissue with potent bioactive molecules. Here we describe fundamental chemical studies that enable biological validation of this approach. Guided by rational design, including computational analysis, we characterize the impact of structural alterations on the cyanine uncaging reaction. A modest change to the ethylenediamine linker (N,N'-dimethyl to N,N'-diethyl) leads to a bathochromic shift in the absorbance maxima, while decreasing background hydrolysis...
April 26, 2017: ACS Central Science
Alexander J Wagner, Dmitry Yu Zubarev, Alán Aspuru-Guzik, Donna G Blackmond
Chiral pentose sugars mediate the enantioselective synthesis of amino acid precursors, with the magnitude of the chiral induction dictated by a subtle cooperativity between sugar hydroxyl groups. Ribose and lyxose give opposite chiral preferences, and theoretical calculations reveal the pseudoenantiomeric nature of transition state structures from the two sugars. Prebiotically plausible mixtures of natural d-sugars lead to enantioenrichment of natural l-amino acid precursors. Temporal monitoring and kinetic modeling of the reaction reveal an unusual dynamic kinetic resolution that shifts toward an enantioselective pathway over time, providing an amplification mechanism for the transfer of chiral information...
April 26, 2017: ACS Central Science
Scott D McCann, Jean-Philip Lumb, Bruce A Arndtsen, Shannon S Stahl
A homogeneous Cu-based catalyst system consisting of [Cu(MeCN)4]PF6, N,N'-di-tert-butylethylenediamine (DBED), and p-(N,N-dimethylamino)pyridine (DMAP) mediates efficient aerobic oxidation of alcohols. Mechanistic study of this reaction shows that the catalyst undergoes an in situ oxidative self-processing step, resulting in conversion of DBED into a nitroxyl that serves as an efficient cocatalyst for aerobic alcohol oxidation. Insights into this behavior are gained from kinetic studies, which reveal an induction period at the beginning of the reaction that correlates with the oxidative self-processing step, EPR spectroscopic analysis of the catalytic reaction mixture, which shows the buildup of the organic nitroxyl species during steady state turnover, and independent synthesis of oxygenated DBED derivatives, which are shown to serve as effective cocatalysts and eliminate the induction period in the reaction...
April 26, 2017: ACS Central Science
Qifan Zhang, Suchol Savagatrup, Paulina Kaplonek, Peter H Seeberger, Timothy M Swager
Janus emulsion assays that rely on carbohydrate-lectin binding for the detection of Escherichia coli bacteria are described. Surfactants containing mannose are self-assembled at the surface of Janus droplets to produce particles with lectin binding sites. Janus droplets orient in a vertical direction as a result of the difference in densities between the hydrocarbon and fluorocarbon solvents. Binding of lectin to mannose(s) causes agglutination and a tilted geometry. The distinct optical difference between naturally aligned and agglutinated Janus droplets produces signals that can be detected quantitatively...
April 26, 2017: ACS Central Science
Hanna M Key, Paweł Dydio, Zhennan Liu, Jennifer Y-E Rha, Andrew Nazarenko, Vida Seyedkazemi, Douglas S Clark, John F Hartwig
Enzymes catalyze organic transformations with exquisite levels of selectivity, including chemoselectivity, stereoselectivity, and substrate selectivity, but the types of reactions catalyzed by enzymes are more limited than those of chemical catalysts. Thus, the convergence of chemical catalysis and biocatalysis can enable enzymatic systems to catalyze abiological reactions with high selectivity. Recently, we disclosed artificial enzymes constructed from the apo form of heme proteins and iridium porphyrins that catalyze the insertion of carbenes into a C-H bond...
April 26, 2017: ACS Central Science
Yonggang Yao, Fengjuan Chen, Anmin Nie, Steven D Lacey, Rohit Jiji Jacob, Shaomao Xu, Zhennan Huang, Kun Fu, Jiaqi Dai, Lourdes Salamanca-Riba, Michael R Zachariah, Reza Shahbazian-Yassar, Liangbing Hu
Nanoparticles (NPs) dispersed within a conductive host are essential for a range of applications including electrochemical energy storage, catalysis, and energetic devices. However, manufacturing high quality NPs in an efficient manner remains a challenge, especially due to agglomeration during assembly processes. Here we report a rapid thermal shock method to in situ synthesize well-dispersed NPs on a conductive fiber matrix using metal precursor salts. The temperature of the carbon nanofibers (CNFs) coated with metal salts was ramped from room temperature to ∼2000 K in 5 ms, which corresponds to a rate of 400,000 K/s...
April 26, 2017: ACS Central Science
Han Altae-Tran, Bharath Ramsundar, Aneesh S Pappu, Vijay Pande
Recent advances in machine learning have made significant contributions to drug discovery. Deep neural networks in particular have been demonstrated to provide significant boosts in predictive power when inferring the properties and activities of small-molecule compounds (Ma, J. et al. J. Chem. Inf. MODEL: 2015, 55, 263-274). However, the applicability of these techniques has been limited by the requirement for large amounts of training data. In this work, we demonstrate how one-shot learning can be used to significantly lower the amounts of data required to make meaningful predictions in drug discovery applications...
April 26, 2017: ACS Central Science
Chen Xu, Arthur Han, Scott C Virgil, Sarah E Reisman
(+)-Ryanodine is a natural product modulator of ryanodine receptors, important intracellular calcium ion channels that play a critical role in signal transduction leading to muscle movement and synaptic transmission. Chemical derivatization of (+)-ryanodine has demonstrated that certain peripheral structural modifications can alter its pharmacology, and that the pyrrole-2-carboxylate ester is critical for high affinity binding to ryanodine receptors. However, the structural variation of available ryanodine analogues has been limited by the challenge of site-specific functionalization of semisynthetic intermediates, such as (+)-ryanodol...
April 26, 2017: ACS Central Science
Benjamín Sánchez-Lengeling, Alán Aspuru-Guzik
No abstract text is available yet for this article.
April 26, 2017: ACS Central Science
Mikhail O Konev, Elizabeth R Jarvo
No abstract text is available yet for this article.
April 26, 2017: ACS Central Science
Alexander R Lippert
No abstract text is available yet for this article.
April 26, 2017: ACS Central Science
Evan W Miller
No abstract text is available yet for this article.
April 26, 2017: ACS Central Science
Deirdre Lockwood
No abstract text is available yet for this article.
April 26, 2017: ACS Central Science
Mark Peplow
No abstract text is available yet for this article.
April 26, 2017: ACS Central Science
Cristina Nevado
No abstract text is available yet for this article.
April 26, 2017: ACS Central Science
Yanyan Xu, Anna Seelig, Simon Bernèche
ATP-binding cassette (ABC) transporters use the energy of ATP binding and hydrolysis to move a large variety of compounds across biological membranes. P-glycoprotein, involved in multidrug resistance, is the most investigated eukaryotic family member. Although a large number of biochemical and structural approaches have provided important information, the conformational dynamics underlying the coupling between ATP binding/hydrolysis and allocrite transport remains elusive. To tackle this issue, we performed molecular dynamic simulations for different nucleotide occupancy states of Sav1866, a prokaryotic P-glycoprotein homologue...
March 22, 2017: ACS Central Science
Florian Allouche, Giuseppe Lapadula, Georges Siddiqi, Wayne W Lukens, Olivier Maury, Boris Le Guennic, Fabrice Pointillart, Jan Dreiser, Victor Mougel, Olivier Cador, Christophe Copéret
Achieving magnetic remanence at single isolated metal sites dispersed at the surface of a solid matrix has been envisioned as a key step toward information storage and processing in the smallest unit of matter. Here, we show that isolated Dy(III) sites distributed at the surface of silica nanoparticles, prepared with a simple and scalable two-step process, show magnetic remanence and display a hysteresis loop open at liquid (4)He temperature, in contrast to the molecular precursor which does not display any magnetic memory...
March 22, 2017: ACS Central Science
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