191 research outputs found

    Encapsulation of a zinc phthalocyanine derivative in self-assembled peptide nanofibers

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    Cataloged from PDF version of article.In this article, we demonstrate encapsulation of octakis(hexylthio) zinc phthalocyanine molecules by non-covalent supramolecular organization within self-assembled peptide nanofibers. Peptide nanofibers containing octakis(hexylthio) zinc phthalocyanine molecules were obtained via a straight-forward one-step self-assembly process under aqueous conditions. Nanofiber formation results in the encapsulation and organization of the phthalocyanine molecules, promoting ultrafast intermolecular energy transfer. The morphological, mechanical, spectroscopic and non-linear optical properties of phthalocyanine containing peptide nanofibers were characterized by TEM, SEM, oscillatory rheology, UV-Vis, fluorescence, ultrafast pump-probe and circular dichroism spectroscopy techniques. The ultrafast pump-probe experiments of octakis(hexylthio) zinc phthalocyanine molecules indicated pH controlled non-linear optical characteristics of the encapsulated molecules within self-assembled peptide nanofibers. This method can provide a versatile approach for bottom-up fabrication of supramolecular organic electronic devices. © 2012 The Royal Society of Chemistry

    Tetrasubstituted copper phthalocyanines : correlation between liquid crystalline properties, films alignment and sensing propertie

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    Copper phthalocyanines (CuPc) containing alkylthio (-S(CH2)nCH3, n=7 and 15), alkyloxy- (-O(CH2)nCH3, n=7 and 15) and polyoxo (-O(CH2CH2O)3CH3 and -S(CH2CH2O)3CH3) substituents were synthesized and investigated to reveal the effects of substituents type (alkylthio, alkyloxy and polyoxo) and the type of the connecting heteroatom (oxygen or sulphur) on the mesogenic properties, films alignment and sensing behaviour. The liquid crystalline properties of these phthalocyanines were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction techniques. The structure and morphology of spun thin films of copper phthalocyanine derivatives were studied by the UV-Vis and Raman spectroscopies as well atomic force microscopy. The sensing properties of CuPc films were studied by the measurement of conductivity change upon interaction with ammonia in the range 10-50 ppm. All investigated films of CuPc derivatives display thermotropic columnar mesomorphism. It was shown that the films with polyoxo- (-O(CH2CH2O)3CH3 and -S(CH2CH2O)3CH3) substituents as well as with alkylthio -S(CH2)nCH3 (n=7) substituents, which are liquid crystalline at room temperature, form ordered films with a random planar alignment of columns. Their films exhibit the better sensor performance with the maximal sensor response for the films of CuPc containing (-S(CH2CH2O)3CH3) substituents

    Orthogonally bifunctionalised polyacrylamide nanoparticles: a support for the assembly of multifunctional nanodevices

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    Polyacrylamide nanoparticles bearing two orthogonal reactive functionalities were prepared by reverse microemulsion polymerisation. Water-soluble photosensitisers and peptide or carbohydrate moieties were sequentially attached to the new nanospecies by orthogonal conjugations based on copper- catalysed azide-alkyne cycloaddition and isothiocyanate chemistry

    Effects of annealing on device parameters of organic field effect transistors using liquid-crystalline tetrasubstituted zinc phthalocyanine

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    The device performance of organic thin-film transistors (OTFTs) employing the solution processed films of room temperature liquid-crystalline tetrasubstituted zinc phthalocyanine derivative was found to depend upon the film morphology. Atomic force microscopic and X-Ray diffraction studies show that the annealing at 70° produced a preferentially unidirectional void-free film with improved surface smoothness. The OTFTs with the annealed films exhibited enhanced conductivity, threefold reduction in threshold voltage, a nearly one order of magnitude increase in the on/off ratio and more than one-third reduction of hysteresis in the transfer characteristics.This work is sponsored by the Air Force Office of Scientific Research, Air Force Material Command, USAF, under grant No. FA8655-13-1-3018. TB acknowledges the financial support from the Ministry of Education and Science of the Russian Federation

    Mitochondria localization induced self-assembly of peptide amphiphiles for cellular dysfunction

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    Achieving spatiotemporal control of molecular self-assembly associated with actuation of biological functions inside living cells remains a challenge owing to the complexity of the cellular environments and the lack of characterization tools. We present, for the first time, the organelle-localized self-assembly of a peptide amphiphile as a powerful strategy for controlling cellular fate. A phenylalanine dipeptide (FF) with a mitochondria-targeting moiety, triphenyl phosphonium (Mito-FF), preferentially accumulates inside mitochondria and reaches the critical aggregation concentration to form a fibrous nanostructure, which is monitored by confocal laser scanning microscopy and transmission electron microscopy. The Mito-FF fibrils induce mitochondrial dysfunction via membrane disruption to cause apoptosis. The organelle-specific supramolecular system provides a new opportunity for therapeutics and in-depth investigations of cellular functions.clos

    Managing Learner’s Affective States in Intelligent Tutoring Systems

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    Abstract. Recent works in Computer Science, Neurosciences, Education, and Psychology have shown that emotions play an important role in learning. Learner’s cognitive ability depends on his emotions. We will point out the role of emotions in learning, distinguishing the different types and models of emotions which have been considered until now. We will address an important issue con-cerning the different means to detect emotions and introduce recent approaches to measure brain activity using Electroencephalograms (EEG). Knowing the influ-ence of emotional events on learning it becomes important to induce specific emo-tions so that the learner can be in a more adequate state for better learning or memorization. To this end, we will introduce the main components of an emotion-ally intelligent tutoring system able to recognize, interpret and influence learner’s emotions. We will talk about specific virtual agents that can influence learner’s emotions to motivate and encourage him and involve a more cooperative work, particularly in narrative learning environments. Pushing further this paradigm, we will present the advantages and perspectives of subliminal learning which inter

    Community assessment to advance computational prediction of cancer drug combinations in a pharmacogenomic screen

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    The effectiveness of most cancer targeted therapies is short-lived. Tumors often develop resistance that might be overcome with drug combinations. However, the number of possible combinations is vast, necessitating data-driven approaches to find optimal patient-specific treatments. Here we report AstraZeneca’s large drug combination dataset, consisting of 11,576 experiments from 910 combinations across 85 molecularly characterized cancer cell lines, and results of a DREAM Challenge to evaluate computational strategies for predicting synergistic drug pairs and biomarkers. 160 teams participated to provide a comprehensive methodological development and benchmarking. Winning methods incorporate prior knowledge of drug-target interactions. Synergy is predicted with an accuracy matching biological replicates for >60% of combinations. However, 20% of drug combinations are poorly predicted by all methods. Genomic rationale for synergy predictions are identified, including ADAM17 inhibitor antagonism when combined with PIK3CB/D inhibition contrasting to synergy when combined with other PI3K-pathway inhibitors in PIK3CA mutant cells.Peer reviewe

    Epigenetic assays for chemical biology and drug discovery

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    An intron polymorphism of the fibronectin gene is associated with end-stage knee osteoarthritis in a Han Chinese population: two independent case-control studies

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    BACKGROUND: Knee osteoarthritis (OA) is a complex disease involving both biomechanical and metabolic factors that alter the tissue homeostasis of articular cartilage and subchondral bone. The catabolic activities of extracellular matrix degradation products, especially fibronectin (FN), have been implicated in mediating cartilage degradation. Chondrocytes express several members of the integrin family which can serve as receptors for FN including integrins α5β1, αvβ3, and αvβ5. The purpose of this study was to determine whether polymorphisms in the FN (FN-1) and integrin genes are markers of susceptibility to, or severity of, knee OA in a Han Chinese population. METHODS: Two independent case–control studies were conducted on 928 patients with knee OA and 693 healthy controls. Ten single nucleotide polymorphisms (SNPs) of FN-1 and the integrin αV gene (ITGAV) were detected using the ABI 7500 real-time PCR system. RESULTS: The AT heterozygote in FN-1 (rs940739A/T) was found to be significantly associated with knee OA (adjusted OR = 1.44; 95% CI = 1.16–1.80) in both stages of the study. FN-1 rs6725958C/A and ITGAV rs10174098A/G SNPs were only associated with knee OA when both study groups were combined. Stratifying the participants by Kellgren-Lawrence (KL) score identified significant differences in the FN-1 rs6725958C/A and rs940739 A/T genotypes between patients with grade 4 OA and controls. Haplotype analyses revealed that TGA and TAA were associated with a higher risk of OA, and that TAG conferred a lower risk of knee OA in the combined population. CONCLUSIONS: Our study suggests that the FN-1 rs940739A/T polymorphism may be an important risk factor of genetic susceptibility to knee OA in the Han Chinese population
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