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Systems chemistry

Nobuo Kimizuka, Nobuhiro Yanai, Masa-Aki Morikawa
Self-assembly of functional molecules into ordered molecular assemblies and fulfillment of potentials unique to their nano-to-mesoscopic structures have been one of the central challenges in chemistry. This Feature Article provides an overview of recent progress in the field of molecular self-assembly with the focus on the triplet-triplet annihilation-based photon upconversion (TTA-UC) and supramolecular storage of photon energy. Based on the integration of molecular self-assembly and photon energy harvesting, triplet energy migration-based TTA-UC has been achieved in varied molecular systems...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Grace Yim, Wenliang Wang, Maulik N Thaker, Stephanie Tan, Gerard D Wright
Modification of natural product backbones is a proven strategy for the development of clinically useful antibiotics. Such modifications have traditionally been achieved through medicinal chemistry strategies or via in vitro enzymatic activities. In an orthogonal approach, engineering of biosynthetic pathways using synthetic biology techniques can generate chemical diversity. Here we report the use of a minimal teicoplanin class glycopeptide antibiotic (GPA) scaffold expressed in a production-optimized Streptomyces coelicolor strain to expand GPA chemical diversity...
September 9, 2016: ACS Infectious Diseases
Jun Chen, Jeremy E Wulff
The Diels-Alder dimerization of cyclopentadiene carboxylic acid (or ester) affords only three products out of a total of 36 possible regioisomers. In this Communication, we compare two competing conceptual models for their ability to rationalize the selective formation of these three compounds. We find that calculated ΔHf values and orbital energy levels are sufficient to describe gross reactivity for the system, but that orbital coefficient arguments (and frontier molecular orbital theory in general) do not reliably predict the regioisomeric outcome for the reaction...
October 18, 2016: Organic & Biomolecular Chemistry
Kaitlin A Doucette, Kelly N Hassell, Debbie C Crans
Improving efficacy and lowering resistance to metal-based drugs can be addressed by consideration of the coordination complex speciation and key reactions important to vanadium antidiabetic drugs or platinum anticancer drugs under biological conditions. The methods of analyses vary depending on the specific metal ion chemistry. The vanadium compounds interconvert readily, whereas the reactions of the platinum compounds are much slower and thus much easier to study. However, the vanadium species are readily differentiated due to vanadium complexes differing in color...
October 3, 2016: Journal of Inorganic Biochemistry
Keren Turjeman, Yechezkel Barenholz
BACKGROUND: Steroids are the most efficacious anti-inflammatory agents. However, their toxicities and side-effects compromise their clinical application. Various strategies and major efforts were dedicated for formulating viable liposomal glucocorticosteroids (GCs), so far none of these were approved. OBJECTIVES: To evaluate these approaches for formulating GC-delivery systems, especially liposomes, and with focus on the Barenholz Lab experience. METHODS: We developed PEGylated nano-liposomes (NSSL) remotely loaded with water-soluble amphipathic weak acid GC-prodrugs...
October 18, 2016: Journal of Drug Targeting
Xiantao Shen, Chuixiu Huang, Sudhirkumar Shinde, Kishore Kumar Jagadeesan, Simon Ekström, Emelie Fritz, Börje Sellergren
This work describes the preparation and investigation of molecularly imprinted polymer (MIP) microgels (MGs) stabilized Pickering emulsions (PE) for their ability to catalyze the formation of disulfide bonds in peptides at the O/W interface. The MIP MGs were synthesized via precipitation polymerization and a programmed initiator change strategy. The MIP MGs were characterized using DLS analysis, SEM measurement and optical microscopy analysis. The dry and wet MIP MGs showed a hydrodynamic diameter of 100 nm and 280 nm, respectively...
October 17, 2016: ACS Applied Materials & Interfaces
John Lee
The molecular mechanisms of the bioluminescence systems of the firefly, bacteria, and those utilizing imidazopyrazinone luciferins such as coelenterazine, are gradually being uncovered using modern biophysical methods such as dynamic (ns-ps) fluorescence spectroscopy, NMR, X-ray crystallography, and computational chemistry. The chemical structures of all reactants are well defined and the spatial structures of the luciferases are providing important insight into interactions within the active cavity. It is generally accepted that the firefly and coelenterazine systems, although proceeding by different chemistries, both generate a dioxetanone high energy species that undergoes decarboxylation to form directly the product in its S1 state, the bioluminescence emitter...
October 17, 2016: Photochemistry and Photobiology
Mengzhe Guo, Dengyang Yin, Jie Han, Cheng Guo, Xiao Li, Liyan Zhang, Yan Du, Haibo Wang, Daoquan Tang
RATIONALE: Mass spectrometry has been developed as one of the common tools for the analysis of the organometallic systems in the gas phase over decades. The study of the fragmentation of organics-metal complexes has attracted much attention since the interesting dissociation pathways exhibited by these compounds are usually different from the protonated analogues. METHODS: In this work, iohexol complexed with different dications such as Mg(2+) , Cu(2+) , and Zn(2+) have been investigated by ESI tandem mass spectrometry...
October 17, 2016: Rapid Communications in Mass Spectrometry: RCM
Alberto Giacomello, Lothar Schimmele, Siegfried Dietrich, Mykola Tasinkevych
A liquid droplet placed on a geometrically textured surface may take on a "suspended" state, in which the liquid wets only the top of the surface structure, while the remaining geometrical features are occupied by vapor. This superhydrophobic Cassie-Baxter state is characterized by its composite interface which is intrinsically fragile and, if subjected to certain external perturbations, may collapse into the fully wet, so-called Wenzel state. Restoring the superhydrophobic Cassie-Baxter state requires a supply of free energy to the system in order to again nucleate the vapor...
October 17, 2016: Soft Matter
B Lucendo-Villarin, H Rashidi, K Cameron, D C Hay
Pluripotent stem cell derived liver cells (hepatocytes) represent a promising alternative to primary tissue for biological and clinical applications. To date, most hepatocyte maintenance and differentiation systems have relied upon the use of animal derived components. This serves as a significant barrier to large scale production and application of stem cell derived hepatocytes. Recently, the use of defined biologics has overcome those limitations in two-dimensional monolayer culture. In order to improve the cell phenotype further, three-dimensional culture systems have been employed to better mimic the in vivo situation, drawing upon materials chemistry, engineering and biology...
May 28, 2016: Journal of Materials Chemistry. B, Materials for Biology and Medicine
Kanjiro Miyata
In recent decades, nucleic acid therapeutics have been attracting much attention because of their potential as treatments for various diseases that require high target specificity. Nevertheless, the number of approved nucleic acid drugs is very limited due to substantially poor bioavailability, thereby generating the need for nucleic acid delivery carriers. A variety of delivery formulations have been reported so far. This review particularly describes polymer-based delivery carriers for systemic administration, highlighting the potential of biological environment-responsive chemistry for overcoming the biological barriers to nucleic acid delivery...
October 17, 2016: Drug Discoveries & Therapeutics
Luis M De Leon-Rodriguez, Yacine Hemar, Guang Mo, Alok K Mitra, Jillian Cornish, Margaret A Brimble
We report the synthesis and characterization of multifunctional peptides comprised of a hydrogel forming β-sheet peptide segment and a matrix metalloproteinase 2 substrate containing a propargylglycinyl linker that is further derivatized with a RGD peptide sequence via "click" chemistry. In contrast to currently known systems, these multifunctional peptides formed gels that are stiffer than those formed by their respective precursors. All the peptides showed reversible thermoresponsive properties, which render them as suitable lead systems for a variety of possible biomedical applications...
October 12, 2016: Acta Biomaterialia
Jovana Trifunović, Vladan Borčić, Momir Mikov
Some biological properties of bile acids and their oxo derivatives have not been sufficiently investigated, although the interest for bile acids as signaling molecules is rising. The aim of this work was to evaluate physico-chemical parametar b (slope) that represents lipophilicity of the examined molecules and to investigate interactions of bile acids with carbonic anhydrase I, II, androgen receptor and CYP450s. 13 candidates were investigated using normal phase thin layer chromatography in two solvent systems...
October 14, 2016: Biomedical Chromatography: BMC
Kyoji Tsuchikama, Zhiqiang An
The antibody-drug conjugate (ADC), a humanized or human monoclonal antibody conjugated with highly cytotoxic small molecules (payloads) through chemical linkers, is a novel therapeutic format and has great potential to make a paradigm shift in cancer chemotherapy. This new antibody-based molecular platform enables selective delivery of a potent cytotoxic payload to target cancer cells, resulting in improved efficacy, reduced systemic toxicity, and preferable pharmacokinetics (PK)/pharmacodynamics (PD) and biodistribution compared to traditional chemotherapy...
October 14, 2016: Protein & Cell
Natalie C Sadler, Hans C Bernstein, Matthew R Melnicki, Moiz A Charania, Eric A Hill, Lindsey N Anderson, Matthew E Monroe, Richard D Smith, Alexander S Beliaev, Aaron T Wright
: Photobiologically synthesized hydrogen (H2) gas is carbon-neutral to produce and clean to combust, making it an ideal biofuel. Cyanothece sp. ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H2 production, a highly perplexing phenomenon because H2 evolving enzymes are O2-sensitive. We employed a systems-level in vivo chemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox, and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity...
October 14, 2016: Applied and Environmental Microbiology
Tanit Haddad, Samantha Noel, Benoît Liberelle, Rouwayda El Ayoubi, Abdellah Ajji, Gregory De Crescenzo
In an effort to design biomaterials that may promote repair of the central nervous system, 3-dimensional scaffolds made of electrospun poly lactic acid nanofibers with interconnected pores were fabricated. These scaffolds were functionalized with polyallylamine to introduce amine groups by wet chemistry. Experimental conditions of the amination protocol were thoroughly studied and selected to introduce a high amount of amine group while preserving the mechanical and structural properties of the scaffold. Subsequent covalent grafting of epidermal growth factor was then performed to further tailor these aminated structures...
October 14, 2016: Biomatter
Eugene Stephane Mananga, Bingwen Hu
The importance of the average Hamiltonian theory and its antecedent the Magnus expansion are discussed. The investigation of its convergence in different situations is very important. In this paper, we introduced a well-established approach to minimize the zeroth order average Hamiltonian for modified composite pulse sequence in quadrupolar spectroscopy of spin-1. We designed two modified composite pulse sequences constructed by modifying the timing sequence in the original composite pulse sequences17. We tested various configurations of times associated with the free evolution of spin system in the modified composite pulses...
October 14, 2016: Journal of Physical Chemistry. A
Sasanka Dalapati, Cheng Gu, Donglin Jiang
Enormous research efforts are focusing on the design and synthesis of advanced luminescent systems, owing to their diverse capability in scientific studies and technological developments. In particular, fluorescence systems based on aggregation-induced emission (AIE) have emerged to show great potential for sensing, bio-imaging, and optoelectronic applications. Among them, integrating AIE mechanisms to design porous polymers is unique because it enables the combination of porosity and luminescence activity in one molecular skeleton for functional design...
October 14, 2016: Small
Joseph A Wright, Jamie N T Peck, Stephen P Cottrell, Aušra Jablonskytė, Vasily S Oganesyan, Christopher J Pickett, Upali A Jayasooriya
The chemistry of metal hydrides is implicated in a range of catalytic processes at metal centers. Gaining insight into the formation of such sites by protonation and/or electronation is therefore of significant value in fully exploiting the potential of such systems. Here, we show that the muonium radical (Mu(.) ), used as a low isotopic mass analogue of hydrogen, can be exploited to probe the early stages of hydride formation at metal centers. Mu(.) undergoes the same chemical reactions as H(.) and can be directly observed due to its short lifetime (in the microseconds) and unique breakdown signature...
October 14, 2016: Angewandte Chemie
Vitaly K Koltover
There are two generally known concepts in biology of aging. Accordingly to the first one, there is a program of aging. The alternative concept advocates that aging proceeds stochastically. In this area of research, free radical-theory of aging, which was put forward by Denham Harman in fifties of XXth century, has determined the most heuristic line. The goal of this review is to demonstrate how the aging program and the aging stochastics are united on the basis of the systems theory of reliability. On this basis, universal features of aging, such as the exponential growth of mortality rate with time and correlation of longevity with the species-specific resting metabolism, are naturally explained...
October 9, 2016: Current Aging Science
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