Substrate-derived Sortase A inhibitors: targeting an essential virulence factor of Gram-positive pathogenic bacteria.

The bacterial transpeptidase Sortase A (SrtA) is a surface enzyme of Gram-positive pathogenic bacteria. It has been shown to be an essential virulence factor for the establishment of various bacterial infections, including septic arthritis. However, the development of potent Sortase A inhibitors remains an unmet challenge.

Three-dimensional liquid foam flow through a hopper resolved by fast X-ray microtomography.

We probe the complex rheological behaviour of liquid foams flowing through a conical constriction. With fast X-ray tomographic microscopy we measure the displacement and deformation of up to fifty thousand bubbles at any single time instance while varying systematically the foam liquid fraction, the bubble size and the flow direction - convergent divergent. The large statistics and high spatio-temporal resolution allows to observe and quantify the deviations from a purely viscous flow.

Correction: Nanoporous hybrid CuO/ZnO/carbon papers used as ultrasensitive non-enzymatic electrochemical sensors.

[This corrects the article DOI: 10.1039/C9RA08223A.].

Island formation of Er(trensal) single-ion magnets on graphene observed on the micrometer scale.

We have studied the morphology of Er(trensal) single-ion molecular magnets adsorbed on graphene/Ru(0001) using X-ray photoemission electron microscopy (X-PEEM). By exploiting the elemental contrast at the erbium M edge we observe the formation of molecular islands of homogeneous height with a lateral size of several micrometers. The graphene/Ru(0001) substrate exhibits two different signal levels in bright-field low-energy electron microscopy (LEEM) and in X-PEEM, which are ascribed to the presence of small-angle rotational domains of the graphene lattice.

Optimizing the quasi-equilibrium state of hot carriers in all-inorganic lead halide perovskite nanocrystals through Mn doping: fundamental dynamics and device perspectives.

Hot carrier (HC) cooling accounts for the significant energy loss in lead halide perovskite (LHP) solar cells. Here, we study HC relaxation dynamics in Mn-doped LHP CsPbI nanocrystals (NCs), combining transient absorption spectroscopy and density functional theory (DFT) calculations. We demonstrate that Mn doping (1) enlarges the longitudinal optical (LO)-acoustic phonon bandgap, (2) enhances the electron-LO phonon coupling strength, and (3) adds HC relaxation pathways Mn orbitals within the bands.

SAR study of 4-arylazo-3,5-diamino-1-pyrazoles: identification of small molecules that induce dispersal of biofilms.

By screening of a collection of 50 000 small-molecule compounds, we recently identified 4-arylazo-3,5-diamino-1-pyrazoles as a novel group of anti-biofilm agents. Here, we report a SAR study based on 60 analogues by examining ways in which the pharmacophore can be further optimized, for example, substitutions in the aryl ring. The SAR study revealed the very potent anti-biofilm compound 4-(2-(2-fluorophenyl)hydrazineylidene)-5-imino-4,5-dihydro-1-pyrazol-3-amine ().

Imaging therapeutic peptide transport across intestinal barriers.

Oral delivery is a highly preferred method for drug administration due to high patient compliance. However, oral administration is intrinsically challenging for pharmacologically interesting drug classes, in particular pharmaceutical peptides, due to the biological barriers associated with the gastrointestinal tract. In this review, we start by summarizing the pharmacological performance of several clinically relevant orally administrated therapeutic peptides, highlighting their low bioavailabilities.

Large plasmonic color metasurfaces fabricated by super resolution deep UV lithography.

In this paper, we demonstrate plasmonic color metasurfaces as large as ∼60 cm fabricated by deep UV projection lithography employing an innovative combination of resolution enhancement techniques. Briefly, in addition to the established off-axis dipole illumination, double- and cross-exposure resolution enhancement of lithography, we introduce a novel element, the inclusion of transparent assist features to the mask layout. With this approach, we demonstrate the fabrication of relief arrays having critical dimensions such as 159 nm nanopillars or 210 nm nanoholes with 300 nm pitches, which is near the theoretical resolution limit expressed by the Rayleigh criterion for the 248 nm lithography tool used in this work.

Side-by-side comparison of Notch- and C83 binding to γ-secretase in a complete membrane model at physiological temperature.

γ-Secretase cleaves the C99 fragment of the amyloid precursor protein, leading to formation of aggregated β-amyloid peptide central to Alzheimer's disease, and Notch, essential for cell regulation. Recent cryogenic electron microscopy (cryo-EM) structures indicate major changes upon substrate binding, a β-sheet recognition motif, and a possible helix unwinding to expose peptide bonds towards nucleophilic attack. Here we report side-by-side comparison of the 303 K dynamics of the two proteins in realistic membranes using molecular dynamics simulations.

Nanoporous hybrid CuO/ZnO/carbon papers used as ultrasensitive non-enzymatic electrochemical sensors.

In this research, we demonstrate a facile approach for the synthesis of a graphite-analogous layer-by-layer heterostructured CuO/ZnO/carbon paper using a graphene oxide paper as a sacrificial template. Cu and Zn were inserted into the interlayer of graphene oxide papers physical absorption and electrostatic effects and then, the M -graphene oxide paper was annealed in air to generate 2D nanoporous CuO/ZnO nanosheets. Due to the graphene oxide template, the structure of the obtained CuO/ZnO nanosheets with an average size of ∼50 nm was duplicated from the graphene oxide paper, which displayed a layer-by-layer structure on the microscale.

Benefiting from Spontaneously Generated 2D/3D Bulk-Heterojunctions in Ruddlesden-Popper Perovskite by Incorporation of S-Bearing Spacer Cation.

2D Ruddlesden-Popper (RP) perovskite solar cells have manifested superior operation durability yet inferior charge transport compared to their 3D counterparts. Integrating 3D phases with 2D RP perovskites presents a compromise to maintain respective advantages of both components. Here, the spontaneous generation of 3D phases embedded in 2D perovskite matrix is demonstrated at room temperature via introducing S-bearing thiophene-2-ethylamine (TEA) as both spacer and stabilizer of inorganic lattices.

Practical Considerations for Continuum Models Applied to Surface Electrochemistry.

Modelling the electrolyte at the electrochemical interface remains a major challenge in ab initio simulations of charge transfer processes at surfaces. Recently, the development of hybrid polarizable continuum models/ab initio models have allowed for the treatment of solvation and electrolyte charge in a computationally efficient way. However, challenges remain in its application.

Structure and dynamics of γ-secretase with presenilin 2 compared to presenilin 1.

Severe early-onset familial Alzheimer's disease (FAD) is caused by more than 200 different mutations in the genes coding for presenilin, the catalytic subunit of the 4-subunit protease complex γ-secretase, which cleaves the C99 fragment of the amyloid precursor protein (APP) to produce Aβ peptides. γ-Secretase exists with either of two homologues, PS1 and PS2. All cryo-electron microscopic structures and computational work has so far focused on γ-secretase with PS1, yet PS2 mutations also cause FAD.

Two-dimensional graphene paper supported flexible enzymatic fuel cells.

Application of enzymatic biofuel cells (EBFCs) in wearable or implantable biomedical devices requires flexible and biocompatible electrode materials. To this end, freestanding and low-cost graphene paper is emerging among the most promising support materials. In this work, we have exploited the potential of using graphene paper with a two-dimensional active surface (2D-GP) as a carrier for enzyme immobilization to fabricate EBFCs, representing the first case of flexible graphene papers directly used in EBFCs.

Unveiling Excitonic Dynamics in High-Efficiency Nonfullerene Organic Solar Cells to Direct Morphological Optimization for Suppressing Charge Recombination.

Nonfullerene acceptors (NFAs)-based organic solar cells (OSCs) have recently drawn considerable research interests; however, their excitonic dynamics seems quite different than that of fullerene acceptors-based devices and remains to be largely explored. A random terpolymer of to pair with a paradigm NFA of 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) such that both complementary optical absorption and very small offsets of both highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels are acquired is designed and synthesized. Despite the small energy offsets, efficient electron/hole transfer between and ITIC is both clearly observed from steady-state photoluminescence and transient absorption spectra and also supported by the measured low exciton binding energy in ITIC.

Oriented attachment growth of monocrystalline cuprous oxide nanowires in pure water.

As a crucial mechanism of non-classical crystallization, the oriented attachment (OA) growth of nanocrystals is of great interest in nanoscience and materials science. The OA process occurring in aqueous solution with chemical reagents has been reported many times, but there are limited studies reporting the OA growth in pure water. In this work, we report the temperature-dependent OA growth of cuprous oxide (CuO) nanowires in pure water through a reagent-free electrophoretic method.

Stacked Janus Device Concepts: Abrupt pn-Junctions and Cross-Plane Channels.

Janus transition metal dichalcogenides with a built-in structural cross-plane (cp) asymmetry have recently emerged as a new class of two-dimensional materials with a large cp dipole. Using first-principles calculations, and a tailored transport method, we demonstrate that stacking graphene and MoSSe Janus structures result in record high homogeneous doping of graphene and abrupt, atomically thin, cross-plane pn-junctions. We show how graphene in contrast to metals can act as electrodes to Janus stacks without screening the cp dipole and predict a large photocurrent response dominated by a cp transport channel in a few-layer stacked device.

Automated Determination of Oxygen-Dependent Enzyme Kinetics in a Tube-in-Tube Flow Reactor.

Enzyme-mediated oxidation is of particular interest to synthetic organic chemists. However, the implementation of such systems demands knowledge of enzyme kinetics. Conventionally collecting kinetic data for biocatalytic oxidations is fraught with difficulties such as low oxygen solubility in water and limited oxygen supply.

Measurement of oxygen transfer from air into organic solvents.

Background: The use of non-aqueous organic media is becoming increasingly important in many biotechnological applications in order to achieve process intensification. Such media can be used, for example, to directly extract poorly water-soluble toxic products from fermentations. Likewise many biological reactions require the supply of oxygen, most normally from air.

Assessment of aflatoxigenic and other fungi in millet and sesame from Plateau State, Nigeria.

Sixteen fonio millet and 17 sesame samples were analysed for incidence of moulds, especially aflatoxigenic species, in order to determine the safety of both crops to consumers, and to correlate aflatoxin levels in the crops with levels produced by toxigenic isolates on laboratory medium. Diverse moulds including and were isolated. was predominantly present in both crops (46-48%), and amongst the potentially aflatoxigenic species, recorded the highest incidence (68% in fonio millet; 86% in sesame kernels).

Plasmonic V-groove waveguides with Bragg grating filters via nanoimprint lithography.

We demonstrate spectral filtering with state-of-the-art Bragg gratings in plasmonic V-groove waveguides fabricated by wafer scale processing based on nanoimprint lithography. Transmission spectra of the devices having 16 grating periods exhibit spectral rejection of the channel plasmon polaritons with 8.2 dB extinction ratio and -3 dB bandwidth of Δλ = 39.

Interfacial electrochemical electron transfer processes in bacterial biofilm environments on Au(111).

We have studied Streptococcus mutans (S. mutans) biofilm growth and growth inhibition on Au(111)-surfaces using atomic force microscopy (AFM) and interfacial electrochemistry of a number of redox probe molecules. AFM of the biofilm growth and growth inhibition on both mica and Au(111)-surfaces was followed by sampling at given times, drying the samples naturally, and imaging.

Polymer photonic crystal dye lasers as Optofluidic Cell Sensors.

Dye doped hybrid polymer lasers are implemented as label free evanescent field biosensors for detection of cells. It is demonstrated that although the coverage is irregular and the cells extend over several lattice constants, the emission wavelength depends linearly on the fraction of the surface covered by the HeLa cells used as model system. Design parameters relating to photonic crystal sensing of large objects are identified and discussed.

Comparison of computational methods for the identification of cell cycle-regulated genes.

Motivation: DNA microarrays have been used extensively to study the cell cycle transcription programme in a number of model organisms. The Saccharomyces cerevisiae data in particular have been subjected to a wide range of bioinformatics analysis methods, aimed at identifying the correct and complete set of periodically expressed genes.

Results: Here, we provide the first thorough benchmark of such methods, surprisingly revealing that most new and more mathematically advanced methods actually perform worse than the analysis published with the original microarray data sets.