bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of a Tunable Self‐Oscillating Polymer with Ureido and Ru(bpy)3 Moieties
Authors: Masuda Tsukuru , Shimada Naohiko , Sasaki Taira , Maruyama Atsushi , Akimoto Aya Mizutani , Yoshida Ryo 
Published: June 2017

AbstractAn upper critical solution temperature (UCST)‐type self‐oscillating polymer was designed that exhibited rhythmic soluble–insoluble changes induced by the Belousov–Zhabotinsky (BZ) reaction. The target polymers were prepared by conjugating Ru(bpy)3, a catalyst for the BZ reaction, to ureido‐containing poly(allylamine‐co‐allylurea) (PAU) copolymers. The Ru(bpy)3‐conjugated PAUs exhibited a UCST‐type phase‐transition behavior, and the solubility of the polymer changed in response to the alternation in the valency of Ru(bpy)3. The ureido content influences the temperature range of self‐oscillation, and the oscillation occurred at higher temperatures than conventional LCST‐type self‐oscillating polymers. Furthermore, the self‐oscillating behavior of the Ru‐PAU could be regulated by addition of urea, which is a unique tuning strategy. We envision that novel self‐oscillating polymers with widely tunable soluble‐insoluble behaviors can be rationally designed based these UCST‐type polymers.
Dendronized Semiconducting Polymer as Photothermal Nanocarrier for Remote Activation of Gene Expression
Authors: Lyu Yan , Cui Dong , Sun He , Miao Yansong , Duan Hongwei , Pu Kanyi 
Published: June 2017

AbstractRegulation of transgene systems is needed to develop innovative medicines. However, noninvasive remote control of gene expression has been rarely developed and remains challenging. We herein synthesize a near‐infrared (NIR) absorbing dendronized semiconducting polymer (DSP) and utilize it as a photothermal nanocarrier not only to efficiently deliver genes but also to spatiotemporally control gene expression in conjunction with heat‐inducible promoter. DSP has a high photothermal conversion efficiency (44.2 %) at 808 nm, permitting fast transduction of NIR light into thermal signals for intracellular activation of transcription. Such a DSP‐mediated remote activation can rapidly and safely result in 25‐ and 4.5‐fold increases in the expression levels of proteins in living cells and mice, respectively. This study thus provides a promising approach to optically regulate transgene systems for on‐demand therapeutic transgene dosing.
Determination of Radical–Radical Distances in Light‐Active Proteins and Their Implication for Biological Magnetoreception
Authors: Nohr Daniel , Paulus Bernd , Rodriguez Ryan , Okafuji Asako , Bittl Robert , Schleicher Erik , Weber Stefan 
Published: June 2017

AbstractLight‐generated short‐lived radial pairs have been suggested to play pivotal roles in cryptochromes and photolyases. Cryptochromes are very probably involved in magnetic compass sensing in migratory birds and the magnetic‐field‐dependent behavior of insects. We examined photo‐generated transient states in the cryptochrome of Drosophila melanogaster and in the structurally related DNA‐repair enzyme Escherichia coli DNA photolyase. Using pulsed EPR spectroscopy, the exchange and dipolar contributions to the electron spin–spin interaction were determined in a straightforward and direct way. With these parameters, radical‐pair partners may be identified and the magnetoreceptor efficiency of cryptochromes can be evaluated. We present compelling evidence for an extended electron‐transfer cascade in the Drosophila cryptochrome, and identified W394 as a key residue for flavin photoreduction and formation of a spin‐correlated radical pair with a sufficient lifetime for high‐sensitivity magnetic‐field sensing.
Imprinted Photonic Hydrogels for the Size‐ and Shell‐Selective Recognition of Nanoparticles
Authors: Gam‐Derouich Sarra , Bourdillon Céline , Lakhdar Chaouche Soraya , Coolen Laurent , Maître Agnès , Mangeney Claire , Schwob Catherine 
Published: June 2017

AbstractSensors based on responsive photonic hydrogels have recently attracted considerable attention for visual medical diagnostics, pharmaceutical bioassays, and environmental monitoring. However, the use of these promising materials for the detection of nanoparticles (NPs) has never been explored so far, although the sensing of nanoobjects is a rapidly evolving area of research. To address this issue, we have combined the concepts of inverse‐opal hydrogels and nanoparticle‐imprinted polymers. In this way, we could obtain a NP‐imprinted photonic hydrogel consisting of a three‐dimensional, highly ordered poly(methacrylic acid) macroporous array, in which nanocavities complementary to the target NPs, in this case colloidal quantum dots, are distributed. This novel type of NP‐imprinted photonic hydrogel sensor was shown to display high sensitivity and selectivity, thus opening new prospects for the development of equipment‐free and cost‐efficient sensing devices for NPs.
Studying the Conformation of a Receptor Tyrosine Kinase in Solution by Inhibitor‐Based Spin Labeling
Authors: Yin Dongsheng M. , Hannam Jeffrey S. , Schmitz Anton , Schiemann Olav , Hagelueken Gregor , Famulok Michael 
Published: June 2017

AbstractThe synthesis of a spin label based on PD168393, a covalent inhibitor of a major anticancer drug target, the epidermal growth factor receptor (EGFR), is reported. The label facilitates the analysis of the EGFR structure in solution by pulsed electron paramagnetic resonance (EPR) spectroscopy. For various EGFR constructs, including near‐full‐length EGFR, we determined defined distance distributions between the two spin labels bound to the ATP binding sites of the EGFR dimer. The distances are in excellent agreement with an asymmetric dimer of the EGFR. Based on crystal structures, this dimer had previously been proposed to reflect the active conformation of the receptor but structural data demonstrating its existence in solution have been lacking. More generally, our study provides proof‐of‐concept that inhibitor‐based spin labeling enables the convenient introduction of site‐specific spin labels into kinases for which covalent or tight‐binding small‐molecule modulators are available.
Discovery of a Calcium‐Dependent Enzymatic Cascade for the Selective Assembly of Hapalindole‐Type Alkaloids: On the Biosynthetic Origin of Hapalindole U
Authors: Zhu Qin , Liu Xinyu 
Published: June 2017

AbstractHapalindole U (4) is a validated biosynthetic precursor to ambiguine alkaloids (Angew. Chem. Int. Ed. 2016, 55, 5780), of which biogenetic origin remains unknown. The recent discovery of AmbU4 (or FamC1) protein encoded in the ambiguine biosynthetic pathway (J. Am. Chem. Soc. 2015, 137, 15366), an isomerocyclase that can rearrange and cyclize geranylated indolenine (2) to a previously unknown 12‐epi‐hapalindole U (3), raised the question whether 3 is a direct precursor to 4 or an artifact arising from the limited in vitro experiments. Here we report a systematic approach that led to the discovery of an unprecedented calcium‐dependent AmbU1‐AmbU4 enzymatic complex for the selective formation of 4. This discovery refuted the intermediacy of 3 and bridged the missing links in the early‐stage biosynthesis of ambiguines. This work further established the isomerocyclases involved in the biogenesis of hapalindole‐type alkaloids as a new family of calcium‐dependent enzymes, where the metal ions are shown critical for their enzymatic activities and selectivities.
Opto‐electrochemical In Situ Monitoring of the Cathodic Formation of Single Cobalt Nanoparticles
Authors: Brasiliense Vitor , Clausmeyer Jan , Dauphin Alice L. , Noël Jean‐Marc , Berto Pascal , Tessier Gilles , Schuhmann Wolfgang , Kanoufi Fréderic 
Published: June 2017

AbstractSingle‐particle electrochemistry at a nanoelectrode is explored by dark‐field optical microscopy. The analysis of the scattered light allows in situ dynamic monitoring of the electrodeposition of single cobalt nanoparticles down to a radius of 65 nm. Larger sub‐micrometer particles are directly sized optically by super‐localization of the edges and the scattered light contains complementary information concerning the particle redox chemistry. This opto‐electrochemical approach is used to derive mechanistic insights about electrocatalysis that are not accessible from single‐particle electrochemistry.
Biologically Controlled Morphology and Twinning in Guanine Crystals
Authors: Hirsch Anna , Palmer Benjamin A. , Elad Nadav , Gur Dvir , Weiner Steve , Addadi Lia , Kronik Leeor , Leiserowitz Leslie 
Published: June 2017

AbstractGuanine crystals are widely used in nature as components of multilayer reflectors. Guanine‐based reflective systems found in the copepod cuticle and in the mirror of the scallop eye are unique in that the multilayered reflectors are tiled to form a contiguous packed array. In the copepod cuticle, hexagonal crystals are closely packed to produce brilliant colors. In the scallop eye, square crystals are tiled to obtain an image‐forming reflecting mirror. The tiles are about 1 μm in size and 70 nm thick. According to analysis of their electron diffraction patterns, the hexagon and square tiles are not single crystals. Rather, each tile type is a composite of what appears to be three crystalline domains differently oriented and stacked onto one another, achieved through a twice‐repeated twinning about their ⟨011⟩ and ⟨021⟩ crystal axes, respectively. By these means, the monoclinic guanine crystal mimics higher symmetry hexagonal and tetragonal structures to achieve unique morphologies.
Silver‐Catalyzed Stereoselective Aminosulfonylation of Alkynes
Authors: Ning Yongquan , Ji Qinghe , Liao Peiqiu , Anderson Edward A. , Bi Xihe 
Published: June 2017

AbstractA silver‐catalyzed intermolecular aminosulfonylation of terminal alkynes with sodium sulfinates and TMSN3 is reported. This three‐component reaction proceeds through sequential hydroazidation of the terminal alkyne and addition of a sulfonyl radical to the resultant vinyl azide. The method enables the stereoselective synthesis of a wide range of β‐sulfonyl enamines without electron‐withdrawing groups on the nitrogen atom. These enamines are found to be suitable for a variety of further transformations.
Bending, Curling, Rolling, and Salient Behavior of Molecular Crystals Driven by [2+2] Cycloaddition of a Styrylbenzoxazole Derivative
Authors: Wang Haoran , Chen Peng , Wu Zhu , Zhao Jinyu , Sun Jingbo , Lu Ran 
Published: June 2017

AbstractWe report interesting photomechanical behaviors of the dynamic molecular crystals of (E)‐2‐(2,4‐dichlorostyryl)benzo[d]oxazole (BOACl24). The photosalient effect of the rod‐like crystal based on a metal‐free olefin driven by photodimerization is observed. Moreover, the needle‐like crystals of BOACl24 exhibit a reversible bending away from a UV light source. The nanofibers curl easily under UV irradiation in an organogel, in which the photo‐induced rolling of a small slice occurs. This suggests that the rapid release of the accumulated strain during photodimerization may lead to a photosalient effect, and the bending or curling happens when the strain is released slowly. Notably, [2+2] cycloaddition takes place between two different conformational isomers of BOACl24 on account of the rotation of the benzoxazole ring around the C−C bond in an excited state before photodimerization. Such topo‐photochemical reaction has not been reported elsewhere.
Synthesis, characterization, and performance evaluation of PES/EDA‐functionalized TiO2 mixed matrix membranes for CO2/CH4 separation
Authors: Eltahir Mustafa Sara Galal Eldin , Mannan Hafiz Abdul , Nasir Rizwan , Mohshim Dzeti Farhah , Mukhtar Hilmi 
Published: June 2017

ABSTRACTPoor adhesion between hydrophobic polymers and hydrophilic inorganic fillers is a challenge that encumbers a high separation performance of mixed matrix membrane (MMM). In this study, Titanium(IV) oxide (TiO2) nanoparticles were functionalized using ethylenediamine (EDA) before embedment in poly(ether sulfone) (PES) polymer matrix. MMMs were synthesized through dry phase inversion technique. Membranes morphology and nanoparticles dispersion was drastically enhanced posterior amine modification indicating an improved adhesion between the polymer and filler particles. Membranes thermal stability was likewise improved as higher degradation temperatures were perceived for PES/EDA–TiO2 MMMs. Gas separation evaluation for pure carbon dioxide (CO2) and methane (CH4) gases revealed a remarkably enhanced separation performance upon amine‐grafting of TiO2 as EDA‐TiO2 MMMs exhibited a higher separation performance as compared to MMMs with pristine TiO2. The highest ideal separation factor achieved was 41.52 with CO2 permeability of 10.11 Barrer at an optimum loading of 5% wt of EDA‐TiO2 which is threefold higher as compared to neat PES membrane and approximately twofold higher than MMMs with pristine TiO2, respectively, at the same filler loading. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45346.
NiCo2S4 Materials for Supercapacitor Applications
Authors: Gao Yong‐Ping , Huang Ke‐Jing 
Published: June 2017

AbstractCobalt–nickel sulfide (NiCo2S4) shows extensive potential for innovative photoelectronic and energetic materials owing to distinctive physical and chemical properties. In this review, representative strategies for the fabrication and application of NiCo2S4 and composite nanostructures are outlined for supercapacitors, with the aim of promoting the development of NiCo2S4 and their composites in the supercapacitor field through an analysis and comparison of diverse nanostructures. A brief introduction into the structures, properties, and morphologies are presented. Further prospects and promising developments of the materials in the supercapacitor field are also proposed.
Engineering CHO cells with an oncogenic KIT improves cells growth, resilience to stress, and productivity
Authors: Mahameed Mohamed , Tirosh Boaz 
Published: June 2017

ABSTRACTAn optimized biomanufacturing process in mammalian cells is contingent on the ability of the producing cells to reach high viable cell densities. In addition, at the peak of growth, cells need to continue producing the biological entity at a consistent quality. Thus, engineering cells with robust growth performance and resilience to variable stress conditions is highly desirable. The tyrosine kinase receptor, KIT, plays a key role in cell differentiation and the survival of several immune cell types. Its oncogenic mutant, D816V, endows cells with high proliferation capacity, and resistance to kinase inhibitors. Importantly, this onco‐KIT mutant when introduced into various cell types is arrested in the endoplasmic reticulum in a constitutively active form. Here, we investigated the effect of oncogenic D816V KIT on the performance of CHO‐K1 cells under conventional tissue culture growth settings and when adapted, to shaking conditions. The onco‐KIT promoted global protein synthesis, elevated the expression of a secretable transgene, enhanced proliferation, and improved the overall titers of a model glycoprotein. Moreover, the expression of the onco‐KIT endowed the cells with a remarkable resistance to various stress conditions. Our data suggest that the introduction of onco‐KIT can serve as a strategy for improving glycoprotein biomanufacturing. Biotechnol. Bioeng. 2017;114: 2560–2570. © 2017 Wiley Periodicals, Inc.
Chemistry of Two Distinct Aeolid Spurilla Species: Ecological Implications
Authors: Ciavatta Maria Letizia , García‐Matucheski Stella , Carbone Marianna , Villani Guido , Nicotera Maria Rosaria , Muniain Claudia , Gavagnin Margherita 
Published: June 2017

The lipophilic extracts of two marine aeolid nudibranch molluscs of the genus Spurilla collected in distinct geographical areas have been chemically analyzed. The Et2O extracts of the nudibranchs were dominated by the presence of usual fatty acids and sterols and contained terpenoid compounds 1 – 3 as minor metabolites. Spurillin A (1) and spurillin B (3) were new molecules whereas cis‐γ‐monocyclofarnesol (2) was already reported in the literature as a synthesis product. Interestingly, bursatellin (4), previously isolated from anaspidean molluscs of the genus Bursatella, was found in the butanol extract of both Spurilla species. Compounds 1 – 4 were not detected in the extracts of the sea‐anemone preys collected together with the molluscs.
Analysis of Structure–Activity Relationships Based on the Hepatitis C Virus SLIIb Internal Ribosomal Entry Sequence RNA‐Targeting GGHYRFK⋅Cu Complex
Authors: Ross Martin James , Fidai Insiya , Cowan James A. 
Published: June 2017

AbstractNew therapeutics for targeting the hepatitis C virus (HCV) have been released in recent years. Although they are less prone to resistance, they are still administered in cocktails as a combination of drugs targeting various aspects of the viral life cycle. Herein, we aim to contribute to an arsenal of new HCV therapeutics by targeting the HCV internal ribosomal entry sequence (IRES) RNA through the development of catalytic metallodrugs that function to degrade rather than inhibit the target molecule. Based on a previously characterized HCV IRES stem‐loop IIb RNA‐targeting metallopeptide Cu‐GGHYrFK (1⋅Cu), an all‐l analogue (3⋅Cu) and a series of additional complexes with single alanine substitutions in the targeting domain were prepared and screened to determine the influence each amino acid side chain on RNA localization and recognition, and catalytic reactivity toward the RNA. Additional substitutions of the tyrosine position in complex 3⋅Cu were also investigated. Good agreement between calculated and measured binding affinities provided support for in silico modeling of the SLIIb RNA binding site and correlations with RNA cleavage sites. Examination of the cleavage products from reaction of the Cu complexes with SLIIb provided mechanistic insights, with the first observation of the 5′‐geminal diol and 5′‐phosphopropenal as products through the use of a Cu⋅ATCUN catalytic motif. Together, the data yielded insights into structure–function relationships that will guide future optimization efforts.
Kinetic Selectivity and Thermodynamic Features of Competitive Imine Formation in Dynamic Covalent Chemistry
Authors: Kulchat Sirinan , Chaur Manuel N. , Lehn Jean‐Marie 
Published: June 2017

AbstractThe kinetic and thermodynamic selectivities of imine formation have been investigated for several dynamic covalent libraries of aldehydes and amines. Two systems were examined, involving the reaction of different types of primary amino groups (aliphatic amines, alkoxy‐amines, hydrazides and hydrazines) with two types of aldehydes, sulfobenzaldehyde and pyridoxal phosphate in aqueous solution at different pD (5.0, 8.5, 11.4) on one hand, 2‐pyridinecarboxaldehyde and salicylaldehyde in organic solvents on the other hand. The reactions were performed separately for given amine/aldehyde pairs as well as in competitive conditions between an aldehyde and a mixture of amines. In the latter case, the time evolution of the dynamic covalent libraries generated was followed, taking into consideration the operation of both kinetic and thermodynamic selectivities. The results showed that, in aqueous solution, the imine of the aliphatic amine was not stable, but oxime and hydrazone formed well in a pH dependent way. On the other hand, in organic solvents, the kinetic product was the imine derived from an aliphatic amine and the thermodynamic products were oxime and hydrazone. The insights gained from these experiments provide a basis for the implementation of imine formation in selective derivatization of mono‐amines in mixtures as well as of polyfunctional compounds presenting different types of amino groups. They may in principle be extended to other dynamic covalent chemistry systems.
A Flexible, Fused, Azomethine–Boron Complex: Thermochromic Luminescence and Thermosalient Behavior in Structural Transitions between Crystalline Polymorphs
Authors: Ohtani Shunsuke , Gon Masayuki , Tanaka Kazuo , Chujo Yoshiki 
Published: June 2017

AbstractThis manuscript reports the multi‐functional boron complex presenting aggregation‐induced emission (AIE), crystallization‐induced emission enhancement (CIEE), and thermosalient behavior accompanying thermochromic luminescence during crystal–crystal transitions by employing the fused azomethine ligand. In particular, we propose that these properties can be explained by molecular “flexibility” toward external stimuli, including temperature changes and photo‐excitation, and two types of crystal polymorphs with different absorption and luminescent properties were obtained. Optical measurements indicated that both polymorphs showed individual AIE and strong CIEE properties. From the investigations, the boron complex showed large structural relaxation and formed the bent structure in the excited state, followed by emission annihilation in the absence of structural restriction. In addition, it was shown that interconversion between these polymorphs could be reversibly induced by heating and cooling. The data from the single‐crystal X‐ray analyses suggested that alteration of crystal packing and intermolecular interaction should influence the luminescent chromism. Moreover, we also found that the crystals showed unusual mechanical behavior, such as hopping and fragmentation by heating and cooling, respectively, which is called thermosalient behavior. It was suggested that the loosely‐fused structure could be responsible for expressing unique optical and mechanical properties.
Labeling and Magnetic Resonance Imaging of Exosomes Isolated from Adipose Stem Cells
Authors: Busato Alice , Bonafede Roberta , Bontempi Pietro , Scambi Ilaria , Schiaffino Lorenzo , Benati Donatella , Malatesta Manuela , Sbarbati Andrea , Marzola Pasquina , Mariotti Raffaella 
Published: June 2017

AbstractAdipose stem cells (ASC) represent a promising therapeutic approach for neurodegenerative diseases. Most biological effects of ASC are probably mediated by extracellular vesicles, such as exosomes, which influence the surrounding cells. Current development of exosome therapies requires efficient and noninvasive methods to localize, monitor, and track the exosomes. Among imaging methods used for this purpose, magnetic resonance imaging (MRI) has advantages: high spatial resolution, rapid in vivo acquisition, and radiation‐free operation. To be detectable with MRI, exosomes must be labeled with MR contrast agents, such as ultra‐small superparamagnetic iron oxide nanoparticles (USPIO). Here, we set up an innovative approach for exosome labeling that preserves their morphology and physiological characteristics. We show that by labeling ASC with USPIO before extraction of nanovesicles, the isolated exosomes retain nanoparticles and can be visualized by MRI. The current work aims at validating this novel USPIO‐based exosome labeling method by monitoring the efficiency of the labeling with MRI both in ASC and in exosomes. © 2017 by John Wiley & Sons, Inc.
Traction Force Microscopy in 3‐Dimensional Extracellular Matrix Networks
Authors: Cóndor M. , Steinwachs J. , Mark C. , García‐Aznar J.M. , Fabry B. 
Published: June 2017

AbstractCell migration through a three‐dimensional (3‐D) matrix depends strongly on the ability of cells to generate traction forces. To overcome the steric hindrance of the matrix, cells need to generate sufficiently high traction forces but also need to distribute these forces spatially in a migration‐promoting way. This unit describes a protocol to measure spatial maps of cell traction forces in 3‐D biopolymer networks such as collagen, fibrin, or Matrigel. Traction forces are computed from the relationship between measured force‐induced matrix deformations surrounding the cell and the known mechanical properties of the matrix. The method does not rely on knowledge of the cell surface coordinates and takes nonlinear mechanical properties of the matrix into account. © 2017 by John Wiley & Sons, Inc.