Bibliographies thématiques / Aggregation Induced Emission Active Molecule

Littérature scientifique sur le sujet « Aggregation Induced Emission Active Molecule »

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Publié le 7 septembre 2023

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Articles de revues sur le sujet "Aggregation Induced Emission Active Molecule"

Chen, Ying, Ke Ma, Ting Hu, Bo Jiang, Bin Xu, Wenjing Tian, Jing Zhi Sun et Wenke Zhang. « Investigation of the binding modes between AIE-active molecules and dsDNA by single molecule force spectroscopy ». Nanoscale 7, n^o 19 (2015) : 8939–45. http://dx.doi.org/10.1039/c5nr01247c.

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Gao, Ying, Chengyuan Qin, Yong Nie, Wei Liu, Tianrui Li et Xuchuan Jiang. « Recent Progress in Aggregation-Induced Emission-Active Organic Small Molecule Inorganic Nanocomposites ». Chinese Journal of Organic Chemistry 40, n^o 8 (2020) : 2254. http://dx.doi.org/10.6023/cjoc202003036.

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Chaudhary, Jagrity, Vibhor Mittal, Shivangi Mishra, Ankita Daiya, Rajdeep Chowdhury, Inamur Rahaman Laskar et Ram Kinkar Roy. « A New Aggregation Induced Emission Active Halochromic White Light Emissive Molecule : Combined Experimental and Theoretical Study ». Journal of Physical Chemistry C 124, n^o 28 (27 mai 2020) : 15406–17. http://dx.doi.org/10.1021/acs.jpcc.0c01067.

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Raichure, Pramod C., Vishal Kachwal et Inamur Rahaman Laskar. « ‘Aggregation-Induced Emission’ Active Mono-Cyclometalated Iridium(III) Complex Mediated Efficient Vapor-Phase Detection of Dichloromethane ». Molecules 27, n^o 1 (29 décembre 2021) : 202. http://dx.doi.org/10.3390/molecules27010202.

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Selective vapor-phase detection of dichloromethane (DCM) is a challenge, it being a well-known hazardous volatile organic solvent in trace amounts. With this in mind, we have developed an ‘Aggregation-induced Emission’ (AIE) active mono-cyclometalated iridium(III)-based (M1) probe molecule, which detects DCM sensitively and selectively in vapor phase with a response time <30 s. It reveals a turn-on emission (non-emissive to intense yellow) on exposing DCM vapor directly to the solid M1. The recorded detection limit is 4.9 ppm for DCM vapor with pristine M1. The mechanism of DCM detection was explored. Moreover, the detection of DCM vapor by M1 was extended with a low-cost filter paper as the substrate. The DCM is weakly bound with the probe and can be removed with a mild treatment, so, notably, the probe can be reused.

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DONG, YONG QIANG, CHENYU LI, WEIJUN ZHAO, YUPING DONG et BEN ZHONG TANG. « STIMULUS RESPONSIVE LUMINESCENT MATERIALS : CRYSTALLIZATION-INDUCED EMISSION ENHANCEMENT ». Journal of Molecular and Engineering Materials 01, n^o 03 (septembre 2013) : 1340010. http://dx.doi.org/10.1142/s2251237313400108.

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Crystallization of a luminogen normally red-shifts and weakens its emission. During investigation of some luminogens exhibiting aggregation-induced emission (AIE), we first noticed that some AIE active luminogens display higher photoluminescence (PL) intensity and bluer emission in the crystalline state than in their amorphous phase, which is termed as crystallization induced emission enhancement (CIEE). The twisted conformations of CIEE active molecules afford loose packing patterns and rule out any detrimental strong interaction. Molecular conformations are locked more tightly in crystals than those in amorphous solid due to the regular weak interactions in crystals, which affords the CIEE effect. The loose packing patterns facilitate emission switching through morphology modulation. Many AIE active molecules have been developed based on restriction of intramolecular rotation (RIR) mechanism, and we obtained many CIEE compounds from those AIE active luminogens and investigated their utilities as stimuli responsive functional materials, especially as chemosensors, thermosensor, mechanosensors and solid-state emitters. Thus, we provide a possible design strategy for the stimuli responsive solid luminescent materials.

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Tang, Baolei, Huapeng Liu, Feng Li, Yue Wang et Hongyu Zhang. « Single-benzene solid emitters with lasing properties based on aggregation-induced emissions ». Chemical Communications 52, n^o 39 (2016) : 6577–80. http://dx.doi.org/10.1039/c6cc02616h.

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Highly efficient single-benzene solid emitters exhibiting aggregation-induced emission (AIE), crystallization-enhanced emission (CEE), as well as amplified spontaneous emission (ASE) have been obtained based on structurally simple ESIPT-active organic molecules.

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Tian, Guangjun, Dexian Sun, Yaogang Zhang et Xi Yu. « Franck–Condon Blockade and Aggregation‐Modulated Conductance in Molecular Devices Using Aggregation‐Induced Emission‐Active Molecules ». Angewandte Chemie International Edition 58, n^o 18 (23 avril 2019) : 5951–55. http://dx.doi.org/10.1002/anie.201900731.

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Tian, Guangjun, Dexian Sun, Yaogang Zhang et Xi Yu. « Franck–Condon Blockade and Aggregation‐Modulated Conductance in Molecular Devices Using Aggregation‐Induced Emission‐Active Molecules ». Angewandte Chemie 131, n^o 18 (23 avril 2019) : 6012–16. http://dx.doi.org/10.1002/ange.201900731.

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Ohtani, Shunsuke, Masayuki Gon, Kazuo Tanaka et Yoshiki Chujo. « The Design Strategy for an Aggregation- and Crystallization-Induced Emission-Active Molecule Based on the Introduction of Skeletal Distortion by Boron Complexation with a Tridentate Ligand ». Crystals 10, n^o 7 (15 juillet 2020) : 615. http://dx.doi.org/10.3390/cryst10070615.

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We describe here a new design strategy for obtaining boron complexes with aggregation- and crystallization-induced emission (AIE and CIE, respectively) properties based on the introduction of skeletal distortion. According to our recent results, despite the fact that an almost planar structure and robust conjugation were obtained, the boron azomethine complex provided a slight emission in solution and an enhanced emission in aggregation and crystal. Quantum calculation results propose that unexpected emission annihilation in solution could be caused through intramolecular bending in the excited state. Herein, to realize this unique molecular motion and obtain AIE and CIE molecules, the phenyl quinoline-based boron complexes BPhQ and BPhQm with distorted and planar structures were designed and synthesized, respectively. BPhQm showed emission in solution and aggregation-caused quenching (ACQ, BPhQm: ΦF,sol. = 0.21, ΦF,agg. = 0.072, ΦF,cryst. = 0.051), while BPhQ exhibited a typical AIE and CIE (BPhQ: ΦF,sol. = 0.008, ΦF,agg. = 0.014, ΦF,cryst. = 0.017). The optical data suggest that a large degree of molecular motion should occur in BPhQ after photo-excitation because of the intrinsic skeletal distortion. Furthermore, single-crystal X-ray diffraction data indicate that the distorted π-conjugated system plays a positive role in presenting solid-state emission by inhibiting consecutive π–π interactions. We demonstrate in this paper that the introduction of the distorted structure by boron complexation should be a new strategy for realizing AIE and CIE properties.

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Yu, Hao, Binjie Chen, Huiming Huang, Zhentao He, Jiangman Sun, Guan Wang, Xinggui Gu et Ben Zhong Tang. « AIE-Active Photosensitizers : Manipulation of Reactive Oxygen Species Generation and Applications in Photodynamic Therapy ». Biosensors 12, n^o 5 (18 mai 2022) : 348. http://dx.doi.org/10.3390/bios12050348.

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Photodynamic therapy (PDT) is a non-invasive approach for tumor elimination that is attracting more and more attention due to the advantages of minimal side effects and high precision. In typical PDT, reactive oxygen species (ROS) generated from photosensitizers play the pivotal role, determining the efficiency of PDT. However, applications of traditional PDT were usually limited by the aggregation-caused quenching (ACQ) effect of the photosensitizers employed. Fortunately, photosensitizers with aggregation-induced emission (AIE-active photosensitizers) have been developed with biocompatibility, effective ROS generation, and superior absorption, bringing about great interest for applications in oncotherapy. In this review, we review the development of AIE-active photosensitizers and describe molecule and aggregation strategies for manipulating photosensitization. For the molecule strategy, we describe the approaches utilized for tuning ROS generation by attaching heavy atoms, constructing a donor-acceptor effect, introducing ionization, and modifying with activatable moieties. The aggregation strategy to boost ROS generation is reviewed for the first time, including consideration of the aggregation of photosensitizers, polymerization, and aggregation microenvironment manipulation. Moreover, based on AIE-active photosensitizers, the cutting-edge applications of PDT with NIR irradiated therapy, activatable therapy, hypoxic therapy, and synergistic treatment are also outlined.

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Thèses sur le sujet "Aggregation Induced Emission Active Molecule"

Yu, Wai Hong. « Synthesis, Characterization and application studies of new aggregation-induced emission (AIE)-active materials ». HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/496.

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The structural design, synthesis and characterization of luminogens with aggregation-induced emission (AIE) properties are studied in this thesis. The remarkable emission properties, thermal stability and biocompatibility of the AIE-active materials demonstrate the promising applications in bioimaging and organic light-emitting diodes (OLEDs).;Chapter 1 introduces the existence of aggregation-caused quenching (ACQ) effect in most conventional organic dyes as well as phosphorescent transitional metal complexes. Discovery of AIE and its mechanical study allow further exploration of usage in organic luminescent materials. This chapter also gives some examples and the applications these AIE-active compounds.;In Chapter 2, a series of cyanostilbenes with simple electron donor (D)-p-electron acceptor (A) structure are presented and synthesized. They exhibit remarkable AIE effect as well as deep red emission peak in 95 % water fraction in THF. These results indicate that attachment of these electron acceptors provides alternative strategy for designing highly emissive AIE-active materials.;In Chapter 3, strongly emissive cyanostilbenes with phenothiazine unit are designed and synthesized. This chapter also investigates the effect of substituents in phenothiazine and terminal cyanostilbene on the photophysical properties and AIE effect. The results suggest that they are AIE-active with different sizes in nano-aggregates. Furthermore, these dyes exhibit clear and strong fluorescence in live cell imaging with excellent biocompatibility.;In Chapter 4, a series of AIE-active phosphorescent Pt(II) complexes made up of C^N^C tridentate ligands are designed and synthesized. They exhibit different morphologies and emission properties upon aggregation in 90 % water in acetonitrile although similar tridentate ligands are applied. One of the complexes in this chapter show nano-rod formation with the highest quantum efficiency in aggregated state, suggesting that rapid self-assembly process occurs to prevent non-radiative decay and oxygen quenching.;In Chapter 5, a series of bis-cyanostyryl fluorophores are designed and synthesized. They are emissive in solid state with colour range from orange to NIR region. Furthermore, they are AIE-active and some of them may contain hybridized local and charge transfer (HLCT) excited state to achieve highly efficient emission upon solvatochromic investigation. Some bis-cyanostyryl thiophenes are fabricated in OLED devices show deep-red to NIR emission, indicative of a promising way to design solid-state NIR-emissive compounds using bis-cyanostyryl derivatives.;Finally, Chapter 6 and 7 present the concluding remarks and the experimental details of the work in Chapters 2 to 5, respectively.

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Ohtani, Shunsuke. « Creation of Emissive and Functional Materials Based on Fused-Boron Complexes ». Kyoto University, 2021. http://hdl.handle.net/2433/261618.

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Chowdhury, Aniket. « Vinylanthracene and Triphenylamine Based Luminescent Molecular Systems : From Aggregation-Induced Emission to Explosive Detection ». Thesis, 2016. http://etd.iisc.ac.in/handle/2005/2968.

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In the last few years, considerable efforts have been given to develop sensitive and effective sensors for explosive materials and to generate systems which exhibit high luminescence in both solution and solid-state. The increasing number of terrorist activities around the world have prompted scientists to design effective ways to detect and disarm even the trace amount of explosives. The nitroaromatics (NACs) are the common constituents of most of the explosives due to high explosive velocity and ease of availability. The NACs were extensively used as the main constituents in landmines until World War II. Apart from their explosive behavior, the NACs are well-known environmental pollutants. The industrial waste and the leakages from unexploded landmines are the major contributors towards the soil and ground water contamination. Presently for effective detection of trace amount of explosives, skilled canines and metal based detectors are commonly used. The canines are trained for a specific type of explosives which limit their ability to detect different types of substrates. The chemical sensors that work on the principle of colorimetric and/or fluorimetric detection techniques have emerged as suitable alternative due to cheap production cost, portability and sensitivity. Different types of materials including conjugated polymers, metal-organic frameworks (MOFs), and quantum-dots have been reported as efficient chemosensors for NACs. However, poor solubility in the common organic solvents, low solid-state fluorescence, very high molecular weight and lack of signal amplification have restricted the application of these material for in-field testing. Renewed interests have been invested in small molecule based systems; and metal-organic discrete molecular architectures due to precise control over their photophysical properties and the supramolecular interaction among neighboring molecules that facilitates energy migration among the molecular backbone. On the other hand, recently post-synthetic modification of different molecular systems including MOFs and polymers has emerged as a potential technique to incorporate desired functional groups into the system and to tune their properties with the retention of basic structures. Reports on the post-synthetic modification of discrete metal-organic architectures are rare due to the delicate nature of the metal-organic bonds that ruptures on mild environmental changes. Therefore, post-synthetic functionalization of discrete molecular systems using mild reaction conditions will open up a myriad of possibilities to generate new systems with desired characteristics. Chapter 1 of the thesis will briefly discuss the history of different explosive materials including different detection methodologies that are widely used. It will also include a brief discussion on different small molecular systems with high solid-state luminescence. In Chapter 2, design and synthesis of triphenylamine-based two Platinum(Pt)(II) molecules functionalized with carboxylic acid and ester groups including their organic analogues have been discussed. The triphenylamine core was chosen due its unique non-planarity and luminescence. On the other hand, Pt(II) center was incorporated to increase intermolecular spacing in solid-state that can induce high luminescence. Scheme 1. Schematic representation of fluorescence quenching using small molecules. All the four molecules were found to be highly sensitive towards NACs including picric acid and dinitrophenol. Although the molecules exhibited similar sensitivity in solution, the carboxylic acid analogues demonstrated superior sensitivity in solid-state. Careful observation of the crystal structures of the systems revealed the acid analogues were oriented in a 2-D grid-like pattern that facilitated energy migration among neighboring molecules (Scheme 1.). Chapter 3 describes design, synthesis, and NACs sensing behavior of anthracene-based four purely organic small molecules. The molecules exhibited high selectivity towards picric acid only. All the molecules were found to be highly emissive in both solution and solid-state due to the vinylanthracene backbone (Scheme 2.). Scheme 2. Schematic representation of fluorescence quenching and solid-state sensing behavior. Chapter 4 discusses the strategy to develop mechano-fluorochromic and AIE active triphenylamine-based Pt(II) complex and its organic analogue. The twisted triphenylamine backbone restricted molecular close packing in solid-state; and weak C-H-- interactions were utilized to hinder the motion of the phenyl rings. As a result, the molecules were highly emissive in solid-state. Grinding disrupted the intermolecular interactions and thus mechano-fluorochromic behavior was observed. Due to twisted backbone, the molecules were also found to be AIE active. Both the systems containing terminal aldehyde groups were finally utilized for selective detection of biomolecule cysteine (Scheme 3.). Scheme 3. Mechano-fluorochromic and AIE behavior of the triphenylamine based Pt(II) complex. In Chapter 5 vinylanthracene-based linear donor was used in combination with carbazole-based 90° and triphenylamine-based 120° Pt(II) acceptors to generate (4+4) and (6+6) molecular squares and hexagons, respectively. The vinylanthracene backbone imparts high solution and solid-state luminescence to the system as well as made them AIE active. The molecules were further investigated for the solution and solid-state sensing for NACs and found to be effective for trinitrotoluene (TNT) and dinitrotoluene (DNT) (Scheme 4.). Scheme 4. Schematic representation of AIE active molecular square and its NACs sensing. Chapter 6 describes the formation of Pd3 self-assembled molecular trinuclear barrels containing triphenylamine imidazole donors and Pd(II) acceptors. Using Knoevenagel condensation the aldehyde group present in the barrel was post-synthetically functionalized with Meldrum’s acid. From spectroscopic characterization, it was proved that the structural integrity remained intact after the post-modification treatment (Scheme 6.). Surprisingly, pre-synthetic modification of the donor alone with Meldrum’s acid followed by self-assembly treatment with the Pd(II) ion did not yield trigonal barrel 6.8. Scheme 6. Post-synthetic functionalization of trinuclear barrels using Knoevenagel condensation.(For colour pictures pl see the abstract pdf file)

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Chapitres de livres sur le sujet "Aggregation Induced Emission Active Molecule"

Chen, Qi, et Bao-Hang Han. « Carbohydrate-Functionalized AIE-Active Molecules as Luminescent Probes for Biosensing ». Dans Aggregation-Induced Emission : Fundamentals, 189–207. Chichester, United Kingdom : John Wiley and Sons Ltd, 2013. http://dx.doi.org/10.1002/9781118735183.ch27.

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Tanaka, Kazuo, et Yoshiki Chujo. « Rational Designs of AIE-Active Molecules and Luminochromic Materials Based on Group 13 Element-Containing Element-Blocks ». Dans Principles and Applications of Aggregation-Induced Emission, 27–42. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99037-8_2.

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Hu, Rongrong, Jacky W. Y. Lam et Ben Zhong Tang. « AIE-Active Polymers ». Dans Aggregation-Induced Emission : Fundamentals, 253–83. Chichester, United Kingdom : John Wiley and Sons Ltd, 2013. http://dx.doi.org/10.1002/9781118735183.ch12.

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Sanji, Takanobu, et Masato Tanaka. « Biogenic Amine Sensing with Aggregation-Induced Emission-Active Tetraphenylethenes ». Dans Aggregation-Induced Emission : Fundamentals, 157–64. Chichester, United Kingdom : John Wiley and Sons Ltd, 2013. http://dx.doi.org/10.1002/9781118735183.ch25.

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Shimizu, Masaki. « Precious Metal-Free Organic Small Molecule Luminophores That Exhibit Room Temperature Phosphorescence ». Dans Principles and Applications of Aggregation-Induced Emission, 43–76. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99037-8_3.

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Siddiqui, Zahir Ali, Aishwarya P. Waghchoure, Sandeep P. More, Nagaiyan Sekar et Rajesh S. Bhosale. « Self-assembled functional materials of aggregation-induced emission active molecules ». Dans Design, Principle and Application of Self-Assembled Nanobiomaterials in Biology and Medicine, 105–21. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-323-90984-6.00012-x.

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Zhang, Yahui, Zhengxu Cai et Yuping Dong. « Chapter 7 AIE-active 1,3-butadiene-based biosensors and bioimagings ». Dans Aggregation-Induced Emission, 155–88. De Gruyter, 2022. http://dx.doi.org/10.1515/9783110672220-007.

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Cametti, Massimo, et Zoran Džolić. « AIE-active supramolecular gel systems ». Dans Aggregation-Induced Emission (AIE), 117–64. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-824335-0.00002-7.

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Pucci, Andrea. « AIE-active materials for photovoltaics ». Dans Aggregation-Induced Emission (AIE), 427–47. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-824335-0.00014-3.

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Zhou, Hui, Ming Hui Chua, Qiang Zhu et Jianwei Xu. « AIE-active polymers for explosive detection ». Dans Aggregation-Induced Emission (AIE), 555–82. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-824335-0.00013-1.

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Actes de conférences sur le sujet "Aggregation Induced Emission Active Molecule"

Luo, Zhijun, Yanan Liu, Menglin Chen, Zongsong Gan et Chang-Sheng Xie. « Aggregation induced emission molecule applied in optical data storage ». Dans Information Storage System and Technology. Washington, D.C. : OSA, 2019. http://dx.doi.org/10.1364/isst.2019.jw4a.13.

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Lu, H. Peter, et X. Sunney Xie. « Dynamics of single Molecules at Room Temperature ». Dans Laser Applications to Chemical and Environmental Analysis. Washington, D.C. : Optica Publishing Group, 1996. http://dx.doi.org/10.1364/lacea.1996.lwb.4.

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Recent advances in fluorescence microscopy have made room temperature single molecule spectroscopy an active area of research. In this work, we investigate the room temperature spectral evolution of single sulforhodamine 101 molecules adsorbed on a silicate glass surface and covered by a PMMA polymer film. Single molecule emission spectra are taken and analyzed with a time resolution of 250 millisecond. Time correlation functions of single molecule spectral trajectories are obtained, with decay time constants inversely proportional to excitation intensities, demonstrating the spectral fluctuation is photo-induced in nature. A stochastic model is developed in order to account for the experimental observations. Understanding the origin of the spectral jumps encountered in the room temperature single molecule experiments is important for conducting further experiments to study chemical dynamics of single molecules in a variety of systems. The latest results of the further experiments will also be presented.

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Barnes, M. J., C. M. Fitzsimmons et L. F. Morton. « THE STRUCTURE OF PLATELET-REACTIVE SITES IN COLLAGENS ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643588.

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Collagen-induced platelet aggregation is an essential step in haemostasis and may be important in thrombosis, particularly that associated with the atherosclerotic plaque. We have located platelet-binding sites in collagen by fragmentation of the molecule with cyanogen bromide (CB) and measurement of the platelet aggregatory activity of the fragments following their renaturation to restore triple-helical configuration and polymerisation to introduce quaternary structure. We have found a high1y-reactive site in collagen type III located in the peptide α1(III)CB4 which was active at a concentration of less than 0.5μg/ml. The equivalent peptide from type I collagen α1(I)CB3 occurring in precisely the same location in the respective parent molecule (residues 403-551) and exhibiting a structure highly homologous to that of α1(III)CB4 was active only at concentrations higher than 200μg/ml. α1(I)CB7, the most active of the type I peptides, was able to cause platelet aggregation at around 5μg/ml whilst the equivalent type III peptide μ1(III)CB5 was inactive. Modification of specific amino acid residues indicated the importance of lysine in the activity of μ1(III)CB4 and of arginine in that of α1(I)CB7. Comparison of the structure of these peptides leads us to conclude that a reactive site comprises two basic residues, a specific distance apart, the conformation of one to the other dictated by collagen triple-helical configuration. One residue occurs in the sequence GlyPro(orHyp)LYS(orARG)GlyGlu, the other in GlyLYS(orARG)Pro(orHyp)GlyGlu. The lower reactivity of α1(I)CB7 relative to α1(III)CB4 can be attributed to the presence of two arginyl rather than lysyl residues and because the spacing of the two in CB4(G1y-LYS-Y-G1y-X-Y-G1y-X-LYS) represents a more favourable one than in CB7(Gly-X-ARG-Gly-X-Y-Gly-X-Y-Gly-ARG-Y).

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Timmons, Sheila, Jadwiqa Grabarek et Jack Hawiqer. « ENDOTOXIC LIPID A INDUCES BINDING OF FIBRINOGEN TO HUMAN PLATELETS VIA PROTEIN KINASE C PATHWAY ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644252.

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Endotoxic Lipid A is the biologically active principle of lipopolysaccharide of Gram-negative bacteria, a most frequent cause of sepsis underlying Disseminated Intravascular Coagulation (DIC) and shock. We have shown that endotoxic Lipid A activates Protein Kinase C in human platelets. Phosphorylation of a 47kDa protein (P47), a marker for Protein Kinase C activation, was observed within the first minute of interaction of Lipid A with platelets. This was accompanied by gradual exposure of the receptor for 125I-labeled fibrinogen (F). Binding of 125I-F was saturable and specific. When Lipid X, a precursor of endotoxic Lipid A and its competitive inhibitor, was used, the binding of 125I-F was blocked with 50% inhibition at a 1:1 stoichiometry between Lipid X and Lipid A. At the same time, phosphorylation of P47 was prevented. Since Lipid X constitutes a "half molecule" of Lipid A, we interpret these results as indicative of competitive blocking of endotoxic Lipid A in terms of Protein Kinase C activation and exposure of platelet receptors for fibrinogen. Binding of fibrinogen is necessary for platelet aggregation and endotoxic Lipid A-induced aggregation was also blocked by Lipid X. Endotoxic Lipid A-induced exposure of fibrinogen receptors via the Protein Kinase C pathway can contribute to involvement of platelets in microcirculatory thrombosis observed in patients with DIC and Gram-negative sepsis

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Larsson, L. J., E. P. Frisch et I. Bjoörk. « PROPERTIES OF THE COMPLEX BETWEEN ou-MACROGLOBULIN AND THE PROTEINASE BRINASE FROM ASPERGILLUS ORYZAE ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643039.

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Brinase, a proteinase from Aspergillus oryzae, has previously been shown to have a significant thrombolytic effect in patients suffering from peripheral arterial disease. Brinase is rapidly bound to α1-proteinase inhibitor and α2-macroglobulin (α2M) in plasma. Since binding of a proteinase to α2 M only results in ste-rical blockingof the active siteand not complete inactivation of the enzyme, it has been suggested that brinase in complex with α2M may retain ability to digest fibrin.To test this hypothesis, we have characterized the binding of brinase to α2M and the properties of the complex formed. Analyses by several techniques showed that one molecule of α2M can maximally bind twomolecules of brinase. The bait region and the thioester bonds of α2M were cleaved in this reaction in a similar manner as in the reactionwith trypsin. Moreover, a conformational change highly similar to that-caused by trypsin was induced in oα2M by brinase, as shown by changes of fluorescence emission, far-u.v. circular dichroism and u.v. absorption difference spectra. Thus, brinase appears to bind to α2M in the same manner as other proteinases. The activities of free brinase and two forms of brinase-α2M complex, produced by reaction of thetwo components in an equimolar ratio or by saturation of inhibitor with enzyme, were compared by two different assays with high-molecular-weight substrates, i.e. hide powder azure or fibrin. The complex formed with equimolar amounts of brinase and α2M showed ∼15% of the activity of free brinase in both assays, whereas the complex formed at saturation of inhibitor with enzyme showed ∼35% of the free brinase activity. Although the brinase-α2M complex, like other α2M proteinase complexes, is eliminated rapidly from plasma, the anility of the complex to cleave high-molecular-weight substrates may be an explanation of the thrombolytic effect of brinase seen in patients.

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Berndt, M. « STRUCTURE AND FUNCTION OF THE GLYCOPROTEIN Ib-IX COMPLEX ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643729.

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At high shear flow, the adhesion of platelets to the exposed vascular subendothelium requires von Willebrand factor (vWF) and is dependent upon a specific platelet membrane adhesion receptor, the human platelet membrane glycoprotein (GP) Ib-IX complex. Recent evidence suggests that vWFbinding to the GP Ib-IX complex plays an important role in other key aspects of hemostasis and thrombosis such as shear-induced platelet aggregation and the interaction of platelets with fibrin.Studies in our laboratory with a seriesof murine monoclonal antibodies directed against epitopes on GP lb, GP IX, or against complex-specificepitopes indicate that GP lb and GP IX exist in the intact platelet membrane as a native heterodimer complex(-25,000 copies/platelet). By analysis onSDS-polyacrylamide gels, GP lb has an apparent molecular weight of 170,000 and cnsists of two disulfide-linked subunits, GP Iba (Mr = 135,000) and GP Ibβ (Mr = 25,000),whilst GP IX has an equivalent molecularweight under both nonreducing and reducing conditions (Mr = 22,000).The ±-chain ofGP lb has a central macroglycopeptide core (Mr =90,000) which is highly glycosylated. At each end of themacroglycopeptide region is a domainsensitive to proteolytic cleavage. Cleavage at the end proximal to the platelet membrane, e.g. by calpain, Serratia marcescens metalloprotease and trypsin, generates two fragments :a Mr =130,000 highly glycosylated fragment termed glycocalicin anda membrane-associated region consisting ofa Mr -25,000 fragment that remains disulfide-linkedto GP Ibβ and associated with GP IX. In resting platelets, the membrane-associated region spans the lipid bilayer linking the GP Ib-IX complex to the platelet endoskeleton via actin-binding protein. This membrane-associated region also contains the domain(s) recognized by quinine/quinidine drug-dependent antibodies. Cleavage at the plasma end of the macroglycopeptide, e.g. by human leukocyte elastase, generates a poorly glycosylated Mr = 45,000 fragment of GP Ibα (peptide tail region) and a heavily glycosylated Mr = 100,000 fragment that remains disulfide-linked to GP Ibg and associated with GP IX. Platelets lacking the N-terminal peptide tail region of GP Iba fail to agglutinate with ristocetin and vWF and show a delayed response to a-thrombin.Polyclonal and monoclonal antibodies against this region also inhibit both these platelet responses suggesting that the peptide tail region contains the binding sites for both α-thrombinand vWF. Rotary shadowingelectron microscopy of purified GP Ib-IX complex shows the structure to be highlyasymmetric with each complex existing asa flexible rod with a globular domain at each end. The overall length of the complexwas =60 nm.The smaller globular domain (peptidetail region) has a diameter of =9nm; the larger globular domain (membrane-associated region), a diameter of =16 nmWe have recently examined whetherthe human platelet GP Ib-IX complex is the receptor for the ristocetin-dependent binding of vWF by reconstitution with the purified components using a solid-phasebead assay. Our approach was to indirectlybind and orientate the GP Ib-IX complex onthe beads via a monoclonal antibody directed against the membrane-associated region of the complex (FMC 25, epitope on GP IX).Immunobeads were chosen as the insoluble matrix because they are uniform in size (=10μm in diameter), impermeable,specifically designed for the coupling of IgG, and because, like platelets, the beads have a net negative charge atneutral pH.Specific binding of 125I-labelled human vWF tothe GP Ib-IX complex-coated immunobeads was strictly ristocetin-dependent with maximal binding occurring atristocetin concentrations >1 mg/ml. Ristocetin-dependent specificbinding of 125I-labelled vWF was saturable.Scatchardanalysis revealed a single classof binding sites for vWF with purified GP Ib-IX complex.Monoclonal antibodies against the Mr = 45,000 peptide tail region ofGP lb which stronglyinhibitthe ristocetin-dependent binding ofvWF toplatelets also strongly inhibited the ristocetin-dependent binding of vWFto the GP Ib-IX coated beads. Monoclonalantibody against either themacroglycopeptide or membrane-associated regions of the GPIb-IX complex did not inhibit the ristocetin-dependent binding of vWF to platelets or to the GP Ib-IX complex-coated beads. Similar functional correlations were obtained with anti-vWFmonoclonal antibodies. The reconstitutiondata therefore confirm the functional roleof the GP Ib-IX complex as a major plateletvWF receptor. The region ofthe vWF molecule involved in binding to the GP Ib-IX complex has been localized toa Mr =50,000 domain towards theN-terminal end of the vWF subunit. The reconstitution assay should prove useful in the further definition of active peptides of vWF that bind tothe human platelet GP Ib-IX complex.

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