Prediction Markets for Paper Evaluations

Title:

Phagocytosis-inspired behaviour in synthetic protocell communities of compartmentalized colloidal objects

Authors:

Rodríguez-Arco, L, Li, M & Mann, S

Year:

2017

Journal:

Nature Materials

Weblink:

http://dx.doi.org/10.1038/nmat4916

Abstract:

The spontaneous assembly of micro-compartmentalized colloidal objects capable of controlled interactions offers a step towards rudimentary forms of collective behaviour in communities of artificial cell-like entities (synthetic protocells). Here we report a primitive form of artificial phagocytosis in a binary community of synthetic protocells in which multiple silica colloidosomes are selectively ingested by self-propelled magnetic Pickering emulsion (MPE) droplets comprising particle-free fatty acid-stabilized apertures. Engulfment of the colloidosomes enables selective delivery and release of water-soluble payloads, and can be coupled to enzyme activity within the MPE droplets. Our results highlight opportunities for the development of new materials based on consortia of colloidal objects, and provide a novel microscale engineering approach to inducing higher-order behaviour in mixed populations of synthetic protocells.

Citations:

29

Citations per year:

15.0

Title:

Combining photochemistry and catalysis: rapid access to sp3 – rich polyheterocycles from simple pyrroles

Authors:

Blackham, EE, Knowles, JP, Burgess, J & Booker-Milburn, KI

Year:

2016

Journal:

Chemical Science

Weblink:

http://dx.doi.org/10.1039/c5sc04062k

Abstract:

Use of FEP flow reactor technology allows access to gram quantities of photochemically-generated tricyclic aziridines. These undergo a range of novel palladium-catalyzed ring-opening and cycloaddition reactions, likely driven by their inherent strain, allowing incorporation of further functionality by fusing additional heterocyclic rings onto these already complex polycyclic cores. This rapid, 2-step access to complex sp3 – rich heterocycles should be of interest to those in the fields of drug discovery and natural product synthesis.

Citations:

18

Citations per year:

5.4

Title:

Rapid and safe ASAP acquisition with EXACT NMR

Authors:

Ndukwe, IE, Shchukina, A, Kazimierczuk, K & Butts, CP

Year:

2016

Journal:

Chemical Communications

Weblink:

http://dx.doi.org/10.1039/c6cc07140f

Abstract:

The dangerously high power levels required for fast ASAP-HSQC and ASAP-HMQC experiments are mitigated by employing EXACT NMR. The utility of this technique is demonstrated by application of the EXACT ASAP-HSQC to chemical reaction monitoring, accelerating data acquisition by up to 2 orders of magnitude – providing evidence of it's value in fast quantitative NMR processes.

Citations:

11

Citations per year:

4.0

Title:

Cooperative Lewis Pairs Based on Late Transition Metals: Activation of Small Molecules by Platinum(0) and B(C6F5)3

Authors:

Forrest, SJK, Clifton, J, Fey, N, Pringle, PG, Sparkes, HA & Wass, DF

Year:

2015

Journal:

Angewandte Chemie

Weblink:

http://dx.doi.org/10.1002/anie.201409872

Abstract:

A Lewis basic platinum(0)–CO complex supported by a diphosphine ligand and B(C6F5)3 act cooperatively, in a manner reminiscent of a frustrated Lewis pair, to activate small molecules such as hydrogen, CO2, and ethene. This cooperative Lewis pair facilitates the coupling of CO and ethene in a new way.

Citations:

21

Citations per year:

4.8

Title:

Lactose as a “Trojan Horse” for Quantum Dot Cell Transport

Authors:

Benito-Alifonso, D, Tremel, S, Hou, B, Lockyear, H, Mantell, J, Fermin, DJ, Verkade, P, Berry, M & Galan, MC

Year:

2014

Journal:

Angewandte Chemie

Weblink:

http://dx.doi.org/10.1002/anie.201307232

Abstract:

A series of glycan‐coated quantum dots were prepared to probe the effect of glycan presentation in intracellular localization in HeLa and SV40 epithelial cells. We show that glycan density mostly impacts on cell toxicity, whereas glycan type affects the cell uptake and intracellular localization. Moreover, we show that lactose can act as a “Trojan horse” on bi‐functionalized QDs to help intracellular delivery of other non‐internalizable glycan moieties and largely avoid the endosomal/lysosomal degradative pathway.

Citations:

33

Citations per year:

6.0

Title:

Measurements and Predictions of Binary Component Aerosol Particle Viscosity

Authors:

Song, YC, Haddrell, A, Bzdek, B, Reid, J, Bannan, T, Topping, D, Percival, CJ & Cai, C

Year:

2016

Journal:

The Journal of Physical Chemistry A

Weblink:

http://dx.doi.org/10.1021/acs.jpca.6b07835

Abstract:

Organic aerosol particles are known to often absorb/desorb water continuously with change in gas phase relative humidity (RH) without crystallization. Indeed, the prevalence of metastable ultraviscous liquid or amorphous phases in aerosol is well-established with solutes often far exceeding bulk phase solubility limits. Particles are expected to become increasingly viscous with drying, a consequence of the plasticizing effect of water. We report here measurements of the variation in aerosol particle viscosity with RH (equal to condensed phase water activity) for a range of organic solutes including alcohols (diols to hexols), saccharides (mono-, di-, and tri-), and carboxylic acids (di-, tri-, and mixtures). Particle viscosities are measured over a wide range (10–3 to 1010 Pa s) using aerosol optical tweezers, inferring the viscosity from the time scale for a composite particle to relax to a perfect sphere following the coalescence of two particles. Aerosol measurements compare well with bulk phase studies (well-within an order of magnitude deviation at worst) over ranges of water activity accessible to both. Predictions of pure component viscosity from group contribution approaches combined with either nonideal or ideal mixing reproduce the RH-dependent trends particularly well for the alcohol, di-, and tricarboxylic acid systems extending up to viscosities of 104 Pa s. By contrast, predictions overestimate the viscosity by many orders of magnitude for the mono-, di-, and trisaccharide systems, components for which the pure component subcooled melt viscosities are ≫1012 Pa s. When combined with a typical scheme for simulating the oxidation of α-pinene, a typical atmospheric pathway to secondary organic aerosol (SOA), these predictive tools suggest that the pure component viscosities are less than 106 Pa s for ∼97% of the 50,000 chemical products included in the scheme. These component viscosities are consistent with the conclusion that the viscosity of α-pinene SOA is most likely in the range 105 to 108 Pa s. Potential improvements to the group contribution predictive tools for pure component viscosities are considered.

Citations:

28

Citations per year:

10.3

Title:

Graphene oxide as a template for a complex functional oxide

Authors:

Boston, R, Bell, A, Ting, V, Rhead, AT, Nakayama, T, Faul, CFJ & Hall, SR

Year:

2015

Journal:

CrystEngComm

Weblink:

http://dx.doi.org/10.1039/c5ce00922g

Abstract:

We report the first use of graphene oxide (GO) as a sacrificial template for the structural direction of complex oxides. The superconductor yttrium barium copper oxide (YBCO) was used as a quarternary oxide test system, with the GO templates being used to create foams and layered paper-like structures which retained the superconducting properties of YBCO.

Citations:

7

Citations per year:

1.8

Title:

Characterization of uncertainties in atmospheric trace gas inversions using hierarchical Bayesian methods

Authors:

Ganesan, AL, Rigby, M, Zammit-Mangion, A, Manning, AJ, Prinn, RG, Fraser, PJ, Harth, CM, Kim, K-R, Krummel, PB, Li, S, Muehle, J, O'Doherty, SJ, Park, S, Salameh, PK, Steele, LP & Weiss, RF

Year:

2014

Journal:

Atmospheric Chemistry and Physics

Weblink:

http://dx.doi.org/10.5194/acp-14-3855-2014

Abstract:

We present a hierarchical Bayesian method for atmospheric trace gas inversions. This method is used to estimate emissions of trace gases as well as "hyper-parameters" that characterize the probability density functions (PDFs) of the a priori emissions and model-measurement covariances. By exploring the space of "uncertainties in uncertainties", we show that the hierarchical method results in a more complete estimation of emissions and their uncertainties than traditional Bayesian inversions, which rely heavily on expert judgment. We present an analysis that shows the effect of including hyper-parameters, which are themselves informed by the data, and show that this method can serve to reduce the effect of errors in assumptions made about the a priori emissions and model-measurement uncertainties. We then apply this method to the estimation of sulfur hexafluoride (SF6) emissions over 2012 for the regions surrounding four Advanced Global Atmospheric Gases Experiment (AGAGE) stations. We find that improper accounting of model representation uncertainties, in particular, can lead to the derivation of emissions and associated uncertainties that are unrealistic and show that those derived using the hierarchical method are likely to be more representative of the true uncertainties in the system. We demonstrate through this SF6 case study that this method is less sensitive to outliers in the data and to subjective assumptions about a priori emissions and model-measurement uncertainties than traditional methods.

Citations:

44

Citations per year:

8.4

Title:

Precise, contactless measurements of the surface tension of picolitre aerosol droplets

Authors:

Bzdek, B, Power, R, Simpson, S, Reid, J & Royall, P

Year:

2016

Journal:

Chemical Science

Weblink:

http://dx.doi.org/10.1039/C5SC03184B

Abstract:

The surface composition and surface tension of aqueous droplets can influence key aerosol characteristics and processes including the critical supersaturation required for activation to form cloud droplets in the atmosphere. Despite its fundamental importance, surface tension measurements on droplets represent a considerable challenge owing to their small volumes. In this work, we utilize holographic optical tweezers to study the damped surface oscillations of a suspended droplet (<10 μm radius) following the controlled coalescence of a pair of droplets and report the first contactless measurements of the surface tension and viscosity of droplets containing only 1–4 pL of material. An advantage of performing the measurement in aerosol is that supersaturated solute states (common in atmospheric aerosol) may be accessed. For pairs of droplets starting at their equilibrium surface composition, surface tensions and viscosities are consistent with bulk equilibrium values, indicating that droplet surfaces respond to changes in surface area on microsecond timescales and suggesting that equilibrium values can be assumed for growing atmospheric droplets. Furthermore, droplet surfaces are shown to be rapidly modified by trace species thereby altering their surface tension. This equilibration of droplet surface tension to the local environmental conditions is illustrated for unknown contaminants in laboratory air and also for droplets exposed to gas passing through a water–ethanol solution. This approach enables precise measurements of surface tension and viscosity over long time periods, properties that currently are poorly constrained.

Citations:

29

Citations per year:

8.2

Title:

Embedded Mean-Field Theory

Authors:

Fornace, ME, Lee, J, Miyamoto, K, Manby, FR & Miller, TF

Year:

2015

Journal:

Journal of Chemical Theory and Computation

Weblink:

http://dx.doi.org/10.1021/ct5011032

Abstract:

We introduce embedded mean-field theory (EMFT), an approach that flexibly allows for the embedding of one mean-field theory in another without the need to specify or fix the number of particles in each subsystem. EMFT is simple, is well-defined without recourse to parameters, and inherits the simple gradient theory of the parent mean-field theories. In this paper, we report extensive benchmarking of EMFT for the case where the subsystems are treated using different levels of Kohn–Sham theory, using PBE or B3LYP/6-31G* in the high-level subsystem and LDA/STO-3G in the low-level subsystem; we also investigate different levels of density fitting in the two subsystems. Over a wide range of chemical problems, we find EMFT to perform accurately and stably, smoothly converging to the high-level of theory as the active subsystem becomes larger. In most cases, the performance is at least as good as that of ONIOM, but the advantages of EMFT are highlighted by examples that involve partitions across multiple bonds or through aromatic systems and by examples that involve more complicated electronic structure. EMFT is simple and parameter free, and based on the tests provided here, it offers an appealing new approach to a multiscale electronic structure.

Citations:

68

Citations per year:

15.4

Title:

Fluorescent Microporous Polyimides Based on Perylene and Triazine for Highly CO2-Selective Carbon Materials

Authors:

Liao, Y, Weber, J & Faul, CFJ

Year:

2015

Journal:

Macromolecules

Weblink:

http://dx.doi.org/10.1021/ma501662r

Abstract:

Carbon dioxide (CO2) capture from point sources like coal-fired power plants is a potential solution for stabilizing atmospheric CO2 content to avoid global warming. Sorbents with high and reversible CO2 uptake, high CO2 selectivity, good chemical and thermal stability, and low cost are desired for the separation of CO2 from N2 in flue or natural gas. We report here, for the first time, on the synthesis of new microporous polyimide (PI) networks from the condensation of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and 1,3,5-triazine-2,4,6-triamine (melamine) using a Lewis acid catalyst zinc acetate/imidazole complex. These PI network materials, prepared in the absence and presence of dimethyl sulfoxide (DMSO) as weak solvent template, exhibit strong fluorescence. Nitrogen-containing carbons can be accessed from our PI networks via a simple thermal pyrolysis route. The successful construction of new microporous PI networks and derived N-containing carbons is shown here to provide promising CO2 sorbents with high uptake capacities (15 wt %) combined with exceptional selectivities over N2 (240), while their fluorescent properties can be exploited for simple sensing.

Citations:

63

Citations per year:

13.9

Title:

Flaws in foldamers: conformational uniformity and signal decay in achiral helical peptide oligomers

Authors:

Le Bailly, BAF, Byrne, L, Diemer, V, Foroozandeh, M, Morris, GA & Clayden, J

Year:

2015

Journal:

Chemical Science

Weblink:

http://dx.doi.org/10.1039/c4sc03944k

Abstract:

Although foldamers, by definition, are extended molecular structures with a well-defined conformation, minor conformers must be populated at least to some extent in solution. We present a quantitative analysis of these minor conformers for a series of helical oligomers built from achiral but helicogenic α-amino acids. By measuring the chain length dependence or chain position dependence of NMR or CD quantities that measure screw-sense preference in a helical oligomer, we quantify values for the decay constant of a conformational signal as it passes through the molecular structure. This conformational signal is a perturbation of the racemic mixture of M and P helices that such oligomers typically adopt by the inclusion of an N or C terminal chiral inducer. We show that decay constants may be very low (<1% signal loss per residue) in non-polar solvents, and we evaluate the increase in decay constant that results in polar solvents, at higher temperatures, and with more conformationally flexible residues such as Gly. Decay constants are independent of whether the signal originates from the N or the C terminus. By interpreting the decay constant in terms of the probability with which conformations containing a screw-sense reversal are populated, we quantify the populations of these alternative minor conformers within the overall ensemble of secondary structures adopted by the foldamer. We deduce helical persistence lengths for Aib polymers that allow us to show that in a non-polar solvent a peptide helix, even in the absence of chiral residues, may continue with the same screw sense for approximately 200 residues.

Citations:

22

Citations per year:

5.1

Title:

Spontaneous assembly of chemically encoded two-dimensional coacervate droplet arrays by acoustic wave patterning

Authors:

Tian, L, Martin, N, Bassindale, PG, Patil, AJ, Li, M, Barnes, A, Drinkwater, BW & Mann, S

Year:

2016

Journal:

Nature Communications

Weblink:

http://dx.doi.org/10.1038/ncomms13068

Abstract:

The spontaneous assembly of chemically encoded, molecularly crowded, water-rich micro-droplets into periodic defect-free two-dimensional arrays is achieved in aqueous media by a combination of an acoustic standing wave pressure field and in situ complex coacervation. Acoustically mediated coalescence of primary droplets generates single-droplet per node micro-arrays that exhibit variable surface-attachment properties, spontaneously uptake dyes, enzymes and particles, and display spatial and time-dependent fluorescence outputs when exposed to a reactant diffusion gradient. In addition, coacervate droplet arrays exhibiting dynamical behaviour and exchange of matter are prepared by inhibiting coalescence to produce acoustically trapped lattices of droplet clusters that display fast and reversible changes in shape and spatial configuration in direct response to modulations in the acoustic frequencies and fields. Our results offer a novel route to the design and construction of ‘water-in-water’ micro-droplet arrays with controllable spatial organization, programmable signalling pathways and higher order collective behaviour.

Citations:

28

Citations per year:

10.2

Title:

Cu2ZnSnS4 Thin Films Generated from a Single Solution Based Precursor: The Effect of Na and Sb Doping

Authors:

Tiwari, D, Harniman, R, Griffiths, I, Cherns, D, Koehler, T, Lin, X, Wang, L, Klenk, R & Fermin, DJ

Year:

2016

Journal:

Chemistry of Materials

Weblink:

http://dx.doi.org/10.1021/acs.chemmater.6b01499

Abstract:

A new solution based route for depositing Cu2ZnSnS4 (CZTS) thin films is described, focusing on the effects of Sb and Na codoping. X-ray diffraction and Raman spectroscopy confirm formation of the kesterite phase with a measurable improvement in crystallinity upon doping. A sharp band gap absorption edge at 1.4 eV is determined from diffuse reflectance measurements, while improvement in the photoluminescence yield and sharpening of the band-to-band emission spectra are observed in the presence of Na and Sb. The performance of devices with the configuration glass/Mo/CZTS/CdS/i-ZnO/ZnO:Al/Ni–Al and total area of 0.5 cm2 is reported. Analysis of over 200 cells shows that introduction of Na and Sb leads to an increase of the average power conversion efficiency from 3.2 ± 0.6 to 5.2 ± 0.3%. The best cell with efficiency of 5.7% is obtained upon Na and Sb doping, featuring 14.9 mA cm–2 short-circuit current, 610 mV open circuit voltage, and 63% fill factor under simulated AM 1.5 illumination. This performance ranks among the highest in pure sulfide CZTS cells. We propose that the improvement in crystallinity and cell performance is linked to the formation of alkali antimony chalcogenides flux during the annealing step, in addition to Sb and Na decreasing disorder in specific lattice positions of the CZTS unit cell.

Citations:

30

Citations per year:

10.2

Title:

Branched Hydrocarbon Low Surface Energy Materials for Superhydrophobic Nanoparticle Derived Surfaces

Authors:

Alexander, S, Eastoe, J, Lord, AM, Guittard, F & Barron, AR

Year:

2016

Journal:

ACS Applied Materials & Interfaces

Weblink:

http://dx.doi.org/10.1021/acsami.5b09784

Abstract:

We present a new class of superhydrophobic surfaces created from low-cost and easily synthesized aluminum oxide nanoparticles functionalized carboxylic acids having highly branched hydrocarbon (HC) chains. These branched chains are new low surface energy materials (LSEMs) which can replace environmentally hazardous and expensive fluorocarbons (FCs). Regardless of coating method and curing temperature, the resulting textured surfaces develop water contact angles (θ) of ∼155° and root-mean-square roughnesses (Rq) ≈ 85 nm, being comparable with equivalent FC functionalized surfaces (θ = 157° and Rq = 100 nm). The functionalized nanoparticles may be coated onto a variety of substrates to generate different superhydrophobic materials.

Citations:

61

Citations per year:

17.5

Title:

Self-Assembly of a Functional Oligo(Aniline)-Based Amphiphile into Helical Conductive Nanowires

Authors:

Bell, OA, Wu, G, Haataja, JS, Broemmel, F, Fey, N, Seddon, AM, Harniman, RL, Richardson, RM, Ikkala, O, Zhang, X & Faul, CFJ

Year:

2015

Journal:

Journal of the American Chemical Society

Weblink:

http://dx.doi.org/10.1021/jacs.5b06892

Abstract:

A tetra(aniline)-based cationic amphiphile, TANI-NHC(O)C5H10N(CH3)3+Br– (TANI-PTAB) was synthesized, and its emeraldine base (EB) state was found to self-assemble into nanowires in aqueous solution. The observed self-assembly is described by an isodesmic model, as shown by temperature-dependent UV–vis investigations. Linear dichroism (LD) studies, combined with computational modeling using time-dependent density functional theory (TD-DFT), suggests that TANI-PTAB molecules are ordered in an antiparallel arrangement within nanowires, with the long axis of TANI-PTAB arranged perpendicular to the nanowire long axis. Addition of either S- or R- camphorsulfonic acid (CSA) to TANI-PTAB converted TANI to the emeraldine salt (ES), which retained the ability to form nanowires. Acid doping of TANI-PTAB had a profound effect on the nanowire morphology, as the CSA counterions’ chirality translated into helical twisting of the nanowires, as observed by circular dichroism (CD). Finally, the electrical conductivity of CSA-doped helical nanowire thin films processed from aqueous solution was 2.7 mS cm–1. The conductivity, control over self-assembled 1D structure and water-solubility demonstrate these materials’ promise as processable and addressable functional materials for molecular electronics, redox-controlled materials and sensing.

Citations:

30

Citations per year:

8.2

Title:

Biosynthesis of Mupirocin by Pseudomonas fluorescens NCIMB 10586 Involves Parallel Pathways

Authors:

Gao, S-S, Hothersall, J, Wu, J, Murphy, AC, Song, Z, Stephens, ER, Thomas, CM, Crump, MP, Cox, RJ, Simpson, TJ & Willis, CL

Year:

2014

Journal:

Journal of the American Chemical Society

Weblink:

http://dx.doi.org/10.1021/ja501731p

Abstract:

Mupirocin, a clinically important antibiotic produced via a trans-AT Type I polyketide synthase (PKS) in Pseudomonas fluorescens, consists of a mixture of mainly pseudomonic acids A, B, and C. Detailed metabolic profiling of mutant strains produced by systematic inactivation of PKS and tailoring genes, along with re-feeding of isolated metabolites to mutant stains, has allowed the isolation of a large number of novel metabolites, identification of the 10,11-epoxidase, and full characterization of the mupirocin biosynthetic pathway, which proceeds via major (10,11-epoxide) and minor (10,11-alkene) parallel pathways.

Citations:

15

Citations per year:

2.9

Title:

Observation of antisite domain boundaries in Cu2ZnSnS4 by atomic-resolution transmission electron microscopy

Authors:

Kattan, N, Griffiths, I, Cherns, D & Fermin, D

Year:

2016

Journal:

Nanoscale

Weblink:

http://dx.doi.org/10.1039/c6nr04185j

Abstract:

Atomic resolution transmission electron microscopy has been used to examine antisite defects in Cu2ZnSnS4 (CZTS) kesterite crystals grown by a hot injection method. High angle annular dark field (HAADF) imaging at sub-0.1 nm resolution, and lower magnification dark field imaging using reflections sensitive to cation ordering, are used to reveal antisite domain boundaries (ADBs). These boundaries, typically 5–20 nm apart, and extending distances of 100 nm or more into the crystals, lie on a variety of planes and have displacements of the type ½[110] or ¼[201], which translate Sn, Cu and Zn cations into antisite positions. It is shown that some ADBs describe a change in the local stoichiometry by removing planes of S and either Cu or Zn atoms, implying that these boundaries can be electrically charged. The observations also showed a marked increase in cation disorder in regions within 1–2 nm of the grain surfaces suggesting that growth of the ordered crystal takes place at the interface with a disordered shell. It is estimated that the ADBs contribute on average ∼0.1 antisite defect pairs per unit cell. Although this is up to an order of magnitude less than the highest antisite defect densities reported, the presence of high densities of ADBs that may be charged suggests these defects may have a significant influence on the efficiency of CZTS solar cells.

Citations:

17

Citations per year:

5.9

Title:

Conformational Switching of a Foldamer in a Multicomponent System by pH-Filtered Selection between Competing Noncovalent Interactions

Authors:

Brioche, J, Pike, SJ, Tshepelevitsh, S, Leito, I, Morris, GA, Webb, SJ & Clayden, J

Year:

2015

Journal:

Journal of the American Chemical Society

Weblink:

http://dx.doi.org/10.1021/jacs.5b03284

Abstract:

Biomolecular systems are able to respond to their chemical environment through reversible, selective, noncovalent intermolecular interactions. Typically, these interactions induce conformational changes that initiate a signaling cascade, allowing the regulation of biochemical pathways. In this work, we describe an artificial molecular system that mimics this ability to translate selective noncovalent interactions into reversible conformational changes. An achiral but helical foldamer carrying a basic binding site interacts selectively with the most acidic member of a suite of chiral ligands. As a consequence of this noncovalent interaction, a global absolute screw sense preference, detectable by 13C NMR, is induced in the foldamer. Addition of base, or acid, to the mixture of ligands competitively modulates their interaction with the binding site, and reversibly switches the foldamer chain between its left and right-handed conformations. As a result, the foldamer–ligand mixture behaves as a biomimetic chemical system with emergent properties, functioning as a “proton-counting” molecular device capable of providing a tunable, pH-dependent conformational response to its environment.

Citations:

26

Citations per year:

6.3

Title:

Synthetic Receptors for the High‐Affinity Recognition of O‐GlcNAc Derivatives

Authors:

Rios, P, Carter, TS, Mooibroek, T, Crump, M, Lisbjerg, M, Pittelkow, M, Supekar, NT, Boons, G-J & Davis, AP

Year:

2016

Journal:

Angewandte Chemie

Weblink:

http://dx.doi.org/10.1002/anie.201510611

Abstract:

The combination of a pyrenyl tetraamine with an isophthaloyl spacer has led to two new water‐soluble carbohydrate receptors (“synthetic lectins”). Both systems show outstanding affinities for derivatives of N‐acetylglucosamine (GlcNAc) in aqueous solution. One receptor binds the methyl glycoside GlcNAc‐β‐OMe with Ka≈20 000 m−1, whereas the other one binds an O‐GlcNAcylated peptide with Ka≈70 000 m−1. These values substantially exceed those usually measured for GlcNAc‐binding lectins. Slow exchange on the NMR timescale enabled structural determinations for several complexes. As expected, the carbohydrate units are sandwiched between the pyrenes, with the alkoxy and NHAc groups emerging at the sides. The high affinity of the GlcNAcyl–peptide complex can be explained by extra‐cavity interactions, raising the possibility of a family of complementary receptors for O‐GlcNAc in different contexts.

Citations:

28

Citations per year:

8.3

Title:

A monodisperse transmembrane α-helical peptide barrel

Authors:

Mahendran, KR, Niitsu, A, Kong, L, Thomson, D, Sessions, R, Woolfson, D & Bayley, H

Year:

2017

Journal:

Nature Chemistry

Weblink:

http://dx.doi.org/10.1038/nchem.2647

Abstract:

The fabrication of monodisperse transmembrane barrels formed from short synthetic peptides has not been demonstrated previously. This is in part because of the complexity of the interactions between peptides and lipids within the hydrophobic environment of a membrane. Here we report the formation of a transmembrane pore through the self-assembly of 35 amino acid α-helical peptides. The design of the peptides is based on the C-terminal D4 domain of the Escherichia coli polysaccharide transporter Wza. By using single-channel current recording, we define discrete assembly intermediates and show that the pore is most probably a helix barrel that contains eight D4 peptides arranged in parallel. We also show that the peptide pore is functional and capable of conducting ions and binding blockers. Such α-helix barrels engineered from peptides could find applications in nanopore technologies such as single-molecule sensing and nucleic-acid sequencing.

Citations:

22

Citations per year:

10.1

Title:

Transition Metal Free C–N Bond Forming Dearomatizations and Aryl C–H Aminations by in Situ Release of a Hydroxylamine-Based Aminating Agent

Authors:

Farndon, J, Ma, X-F & Bower, J

Year:

2017

Journal:

Journal of the American Chemical Society

Weblink:

http://dx.doi.org/10.1021/jacs.7b07830

Abstract:

We outline a simple protocol that accesses directly unprotected secondary amines by intramolecular C–N bond forming dearomatization or aryl C–H amination. The method is dependent on the generation of a potent electrophilic aminating agent released by in situ deprotection of O-Ts activated N-Boc hydroxylamines.

Citations:

17

Citations per year:

9.5

Title:

Oxidative 1,2-Difunctionalization of Ethylene via Gold-Catalyzed Oxyarylation

Authors:

Harper, M, Emmett, E, Bower, J & Russell, CA

Year:

2017

Journal:

Journal of the American Chemical Society

Weblink:

http://dx.doi.org/10.1021/jacs.7b06668

Abstract:

Under the conditions of oxidative gold catalysis, exposure of ethylene to aryl silanes and alcohols generates products of 1,2-oxyarylation. This provides a rare example of a process that allows catalytic differential 1,2-difunctionalization of this feedstock chemical.

Citations:

13

Citations per year:

7.1

Title:

Small Molecule Activation by Intermolecular Zr(IV)-Phosphine Frustrated Lewis Pairs

Authors:

Metters, OJ, Forrest, SJK, Sparkes, HA, Manners, I & Wass, DF

Year:

2016

Journal:

Journal of the American Chemical Society

Weblink:

http://dx.doi.org/10.1021/jacs.5b12536

Abstract:

We report intermolecular transition metal frustrated Lewis pairs (FLPs) based on zirconocene aryloxide and phosphine moieties that exhibit a broad range of small molecule activation chemistry that has previously been the preserve of only intramolecular pairs. Reactions with D2, CO2, THF, and PhCCH are reported. By contrast with previous intramolecular examples, these systems allow facile access to a variety of steric and electronic characteristics at the Lewis acidic and Lewis basic components, with the three-step syntheses of 10 new intermolecular transition metal FLPs being reported. Systematic variation to the phosphine Lewis base is used to unravel steric considerations, with the surprising conclusion that phosphines with relatively small Tolman steric parameters not only give highly reactive FLPs but are often seen to have the highest selectivity for the desired product. DOSY NMR spectroscopic studies on these systems reveal for the first time the nature of the Lewis acid/Lewis base interactions in transition metal FLPs of this type.

Citations:

31

Citations per year:

9.1

Title:

3D Bioprinting Using a Templated Porous Bioink

Authors:

Armstrong, JPK, Burke, M, Carter, BM, Davis, SA & Perriman, AW

Year:

2016

Journal:

Advanced Healthcare Materials

Weblink:

http://dx.doi.org/10.1002/adhm.201600022

Abstract:

3D tissue printing with adult stem cells is reported. A novel cell‐containing multicomponent bioink is used in a two‐step 3D printing process to engineer bone and cartilage architectures.

Citations:

35

Citations per year:

11.8

Title:

Recent and future trends in synthetic greenhouse gas radiative forcing

Authors:

Rigby, M, Prinn, RG, O'Doherty, S, Miller, BR, Ivy, D, Muehle, J, Harth, CM, Salameh, PK, Arnold, T, Weiss, RF, Krummel, PB, Steele, LP, Fraser, PJ, Young, D & Simmonds, PG

Year:

2014

Journal:

Geophysical Research Letters

Weblink:

http://dx.doi.org/10.1002/2013GL059099

Abstract:

Atmospheric measurements show that emissions of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons are now the primary drivers of the positive growth in synthetic greenhouse gas (SGHG) radiative forcing. We infer recent SGHG emissions and examine the impact of future emissions scenarios, with a particular focus on proposals to reduce HFC use under the Montreal Protocol. If these proposals are implemented, overall SGHG radiative forcing could peak at around 355 mW m−2 in 2020, before declining by approximately 26% by 2050, despite continued growth of fully fluorinated greenhouse gas emissions. Compared to “no HFC policy” projections, this amounts to a reduction in radiative forcing of between 50 and 240 mW m−2 by 2050 or a cumulative emissions saving equivalent to 0.5 to 2.8 years of CO2 emissions at current levels. However, more complete reporting of global HFC emissions is required, as less than half of global emissions are currently accounted for.

Citations:

50

Citations per year:

9.6

Title:

Transmission of torque at the nanoscale

Authors:

Williams, I, Oguz, EC, Speck, T, Bartlett, P, Löwen, H & Royall, CP

Year:

2016

Journal:

Nature Physics

Weblink:

http://dx.doi.org/10.1038/nphys3490

Abstract:

In macroscopic mechanical devices, torque is transmitted through gearwheels and clutches. In the construction of devices at the nanoscale, torque and its transmission through soft materials will be a key component. However, this regime is dominated by thermal fluctuations leading to dissipation. Here we demonstrate the principle of torque transmission for a disc-like colloidal assembly exhibiting clutch-like behaviour, driven by 27 particles in optical traps. These are translated on a circular path to form a rotating boundary that transmits torque to additional particles confined to the interior. We investigate this transmission and find that it is determined by solid-like or fluid-like behaviour of the device and a stick–slip mechanism reminiscent of macroscopic gearwheels slipping. The transmission behaviour is predominantly governed by the rotation rate of the boundary and the density of the confined system. We determine the efficiency of our device and thus optimize conditions to maximize power output.

Citations:

9

Citations per year:

2.6

Title:

Short Flow-Photochemistry Enabled Synthesis of the Cytotoxic Lactone (+)-Goniofufurone

Authors:

Ralph, MJ, Ng, S & Booker-Milburn, KI

Year:

2016

Journal:

Organic Letters

Weblink:

http://dx.doi.org/10.1021/acs.orglett.6b00067

Abstract:

A photochemical approach to the cytotoxic lactone (+)-goniofufurone (1) is reported. Paternò–Büchi [2 + 2] photocycloaddition from known enol ether 4, derived from the readily available sugar d-isosorbide, yielded oxetane 7. This slow, dilute reaction was scaled up by using flow photochemistry to yield >40 g of 7. Installation of the key lactone ring was achieved via a unique Wacker-style oxidation of an enol–ether bond. Acid-catalyzed aqueous ring opening provided 1 in five steps from 4 (11.5% overall).

Citations:

9

Citations per year:

2.7

Title:

Synthesis and Confinement of Carbon Dots in Lysozyme Single Crystals Produces Ordered Hybrid Materials with Tuneable Luminescence

Authors:

England, MW, Patil, AJ & Mann, S

Year:

2015

Journal:

Chemistry - A European Journal

Weblink:

http://dx.doi.org/10.1002/chem.201501429

Abstract:

The synthesis and confinement of graphitic nanoparticles (carbon dots) in the nanoscale solvent channels of cross‐linked lysozyme single crystals is used to prepare novel biohybrid luminescent materials. Co‐sequestration of acridine orange within the biohybrid crystals from acidic or neutral solutions yields FRET‐mediated phosphors emitting white or green light, respectively. The results offer a route to new types of tuneable multicolour luminescent materials based on microcrystalline host–guest energy‐transfer systems.

Citations:

6

Citations per year:

1.5

Title:

Heterologous Production of Fungal Maleidrides Reveals the Cryptic Cyclization Involved in their Biosynthesis

Authors:

Williams, K, Szwalbe, AJ, Mulholland, NP, Vincent, JL, Bailey, A, Willis, CL, Simpson, TJ & Cox, RJ

Year:

2016

Journal:

Angewandte Chemie

Weblink:

http://dx.doi.org/10.1002/anie.201511882

Abstract:

Fungal maleidrides are an important family of bioactive secondary metabolites that consist of 7, 8, or 9‐membered carbocycles with one or two fused maleic anhydride moieties. The biosynthesis of byssochlamic acid (a nonadride) and agnestadride A (a heptadride) was investigated through gene disruption and heterologous expression experiments. The results reveal that the precursors for cyclization are formed by an iterative highly reducing fungal polyketide synthase supported by a hydrolase, together with two citrate‐processing enzymes. The enigmatic ring formation is catalyzed by two proteins with homology to ketosteroid isomerases, and assisted by two proteins with homology to phosphatidylethanolamine‐binding proteins.

Citations:

15

Citations per year:

4.8