Encapsulating a single G-quadruplex aptamer in a protein nanocavity

The alpha-hemolysin (alphaHL) protein pore has many applications in biotechnology. This article describes a single-molecule manipulation system that utilizes the nanocavity enclosed by this pore to noncovalently encapsulate a guest molecule. The guest is the thrombin-binding aptamer (TBA) that folds into the G-quadruplex in the presence of cations. Trapping the G-quadruplex in the nanocavity resulted in characteristic changes to the pore conductance that revealed important molecular processes, including spontaneous unfolding of the quartet structure and translocation of unfolded DNA in the pore. Through detection with Tag-TBA, we localized the G-quadruplex near the entry of the beta-barrel inside the nanocavity, where the molecule vibrates and rotates to different orientations. This guest-nanocavity supramolecular system has potential for helping to understand single-molecule folding and unfolding kinetics.     

Regioselectivity prediction of CYP1A2-mediated phase I metabolism

A kinetic, reactivity-binding model has been proposed to predict the regioselectivity of substrates meditated by the CYP1A2 enzyme, which is responsible for the metabolism of planar-conjugated compounds such as caffeine. This model consists of a docking simulation for binding energy and a semiempirical molecular orbital calculation for activation energy. Possible binding modes of CYP1A2 substrates were first examined using automated docking based on the crystal structure of CYP1A2, and binding energy was calculated. Then, activation energies for CYP1A2-mediated metabolism reactions were calculated using the semiempirical molecular orbital calculation, AM1. Finally, the metabolic probability obtained from two energy terms, binding and activation energies, was used for predicting the most probable metabolic site. This model predicted 8 out of 12 substrates accurately as the primary preferred site among all possible metabolic sites, and the other four substrates were predicted into the secondary preferred site. This method can be applied for qualitative prediction of drug metabolism mediated by CYP1A2 and other CYP450 family enzymes, helping to develop drugs efficiently.     

One-pot synthesis of simple alkaloids: 2,3-polymethylene-4(3H)-quinazolinones, luotonin A, tryptanthrin, and rutaecarpine

One-pot synthesis of various 2,3-polymethylene-4(3H)-quinazolinones from anthranilic acid, corresponding lactam and SOCl(2) is described, which can be applicable to the synthesis of simple 4(3H)-quinazolinone-derived alkaloids, such as luotonin A, tryptanthrin, and rutaecarpine.     

Stretchable and Transparent Biointerface Using Cell‐Sheet–Graphene Hybrid for Electrophysiology and Therapy of Skeletal Muscle

Implantable electronic devices for recording electrophysiological signals and for stimulating muscles and nerves have been widely used throughout clinical medicine. Mechanical mismatch between conventional rigid biomedical devices and soft curvilinear tissues, however, has frequently resulted in a low signal to noise ratio and/or mechanical fatigue and scarring. Multifunctionality ranging from various sensing modalities to therapeutic functions is another important goal for implantable biomedical devices. Here, a stretchable and transparent medical device using a cell‐sheet–graphene hybrid is reported, which can be implanted to form a high quality biotic/abiotic interface. The hybrid is composed of a sheet of C2C12 myoblasts on buckled, mesh‐patterned graphene electrodes. The graphene electrodes monitor and actuate the C2C12 myoblasts in vitro, serving as a smart cell culture substrate that controls their aligned proliferation and differentiation. This stretchable and transparent cell‐sheet–graphene hybrid can be transplanted onto the target muscle tissue, to record electromyographical signals, and stimulate implanted sites electrically and/or optically in vivo. Additional cellular therapeutic effect of the cell‐sheet–graphene hybrid is obtained by integrated myobalst cell sheets. Any immune responses within implanted muscle tissues are not observed. This multifunctional device provides many new opportunities in the emerging field of soft bioelectronics.     

Improving Performance and Stability of Flexible Planar‐Heterojunction Perovskite Solar Cells Using Polymeric Hole‐Transport Material

For realizing flexible perovskite solar cells (PSCs), it is important to develop low‐temperature processable interlayer materials with excellent charge transporting properties. Herein, a novel polymeric hole‐transport material based on 1,4‐bis(4‐sulfonatobutoxy)benzene and thiophene moieties (PhNa‐1T) and its application as a hole‐transport layer (HTL) material of high‐performance inverted‐type flexible PSCs are introduced. Compared with the conventionally used poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), the incorporation of PhNa‐1T into HTL of the PSC device is demonstrated to be more effective for improving charge extraction from the perovskite absorber to the HTL and suppressing charge recombination in the bulk perovskite and HTL/perovskite interface. As a result, the flexible PSC using PhNa‐1T achieves high photovoltaic performances with an impressive power conversion efficiency of 14.7%. This is, to the best of our knowledge, among the highest performances reported to date for inverted‐type flexible PSCs. Moreover, the PhNa‐1T‐based flexible PSC shows much improved stability under an ambient condition than PEDOT:PSS‐based PSC. It is believed that PhNa‐1T is a promising candidate as an HTL material for high‐performance flexible PSCs.     

High‐Performance Mesostructured Organic Hybrid Pseudocapacitor Electrodes

The electrodes of a hybrid electrochemical capacitor which utilize the quinone (Q)‐hydroquinone (QH₂) couple, a prototypical organic redox system known to provide fast and reversible proton‐coupled electron‐transfer reactions, are deterministically mesostructured via a colloidal templating strategy to provide good ion and electron transport pathways, enabling a high rate performance. Specifically, a conducting polymer, polypyrrole (PPy), is functionalized with a pseudocapacitive material, a Q/QH₂‐containing catechol derivative, by noncovalent interactions. The mesostructure of this hybrid material is formed into an ordered 3D porous structure by a polystyrene colloidal crystal template‐assisted electrosynthesis. The catechol derivative is sufficiently bound to the PPy through noncovalent interactions to provide a volumetric capacitance as high as ≈130 F cm^?3 and a capacitance retention of ≈75% over 10 000 charging/discharging cycles. When compared with a randomly structured electrode, the deterministically structured electrode exhibits an improved rate performance due to the mesostructure facilitated electron and ion transport.     

Engineering Thermal Conductivity for Balancing Between Reliability and Performance of Bulk Thermoelectric Generators

The nanostructuring approach has significantly contributed to the improving of thermoelectric figure‐of‐merit (ZT) by reducing lattice thermal conductivity. Even though it is an effective method to enhance ZT, the drastically lowered thermal conductivity in some cases can cause thermomechanical issues leading to decreased reliability of thermoelectric generators. Here, an engineering thermal conductivity (κ_eng) is defined as a minimum allowable thermal conductivity of a thermoelectric material in a module, and is evaluated to avoid thermomechanical failure and thermoelectric degradation of a device. Additionally, there is dilemma of determining thermoelectric leg length: a shorter leg is desired for higher W kg^?1, W cm^?3, and W The nanostructuring approach has significantly contributed to the improving of thermoelectric figure‐of‐merit (ZT) by reducing lattice thermal conductivity. Even though it is an effective method to enhance ZT, the drastically lowered thermal conductivity in some cases can cause thermomechanical issues leading to decreased reliability of thermoelectric generators. Here, an engineering thermal conductivity (κ_eng) is defined as a minimum allowable thermal conductivity of a thermoelectric material in a module, and is evaluated to avoid thermomechanical failure and thermoelectric degradation of a device. Additionally, there is dilemma of determining thermoelectric leg length: a shorter leg is desired for higher W kg^?1, W cm^?3, and W $^?1, but it raises the thermomechanical vulnerability issue. By considering a balance between the thermoelectric performance and thermomechanical reliability issues, it is discussed how to improve device reliability of thermoelectric generators and the engineering thermal conductivity of thermoelectric materials.     

Simultaneous detection of fluquinconazole and flusilazole in lettuce using gas chromatography with a nitrogen phosphorus detector: decline patterns at two different locations

Method validations in addition to decline patterns of fluquinconazole and flusilazole in lettuce grown under greenhouse conditions at two different locations were investigated. Following the application of fluquinconazole and flusilazole at a dose rate of 20 mL/20 L water, lettuce samples were collected randomly for up to 7 days post‐application, and simultaneously extracted with acetone, purified through solid‐phase extraction, analyzed via gas chromatography with a nitrogen phosphorus detector, and confirmed through gas chromatography–mass spectrometry. The linearity was excellent, with determination coefficients (R²) between 0.9999 and 1.0. The method was validated in triplicate at two different spiking levels (0.2 and 1.0 mg/kg) with satisfactory recoveries between 75.7 and 97.9% and relative standard deviations of <9. The limit of quantification was 0.01 mg/kg. Both analytes declined very quickly, as can be seen from the short half‐life time of <4 days. Statistical analysis revealed significant differences between residues at different days of sampling, except at 7 days post‐application (triple application). At that point, the decline patterns of fluquinconazole and flusilazole were independent of application rate, location, temperature and humidity. Copyright © 2015 John Wiley & Sons, Ltd.     

Development and validation of an ultra‐performance convergence chromatography method for the quality control of Angelica gigas Nakai

Ultra‐performance convergence chromatography, which integrates the advantages of supercritical fluid chromatography and ultra high performance liquid chromatography technologies, is an environmentally friendly analytical method that uses dramatically reduced amounts of organic solvents. An ultra‐performance convergence chromatography method was developed and validated for the quantification of decursinol angelate and decursin in Angelica gigas using a CSH Fluoro‐Phenyl column (2.1 mm × 150 mm, 1.7 μm) with a run time of 4 min. The method had an improved resolution and a shorter analysis time in comparison to the conventional high‐performance liquid chromatography method. This method was validated in terms of linearity, precision, and accuracy. The limits of detection were 0.005 and 0.004 μg/mL for decursinol angelate and decursin, respectively, while the limits of quantitation were 0.014 and 0.012 μg/mL, respectively. The two components showed good regression (correlation coefficient (r²) > 0.999), excellent precision (RSD < 2.28%), and acceptable recoveries (99.75–102.62%). The proposed method can be used to efficiently separate, characterize, and quantify decursinol angelate and decursin in Angelica gigas and its related medicinal materials or preparations, with the advantages of a shorter analysis time, greater sensitivity, and better environmental compatibility.