The Experts below are selected from a list of 5805 Experts worldwide ranked by ideXlab platform
Lei Jiang - One of the best experts on this subject based on the ideXlab platform.
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Thermochromic Artificial Nacre Based on Montmorillonite
2017Co-Authors: Jingsong Peng, Lei Jiang, Yiren Cheng, Antoni P. Tomsia, Qunfeng ChengAbstract:Nacre-inspired nanocomposites have attracted a great deal of attention in recent years because of their special mechanical properties and universality of the underlying principles of materials engineering. The ability to respond to external stimuli will augment the high toughness and high strength of artificial Nacre-like composites and open new technological horizons for these materials. Herein, we fabricated robust artificial Nacre based on montmorillonite (MMT) that combines robustness with reversible thermochromism. Our artificial Nacre shows great potential in various fields such as aerospace and sensors and opens an avenue to fabricate artificial Nacre responsive to other external stimuli in the future
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robust underwater oil repellent material inspired by columnar Nacre
Advanced Materials, 2016Co-Authors: Tianqi Guo, Jianfeng Wang, Liping Heng, Miaomiao Wang, Lei JiangAbstract:Inspired by natural columnar Nacre, artificial montmorillonite/hydroxyethyl cellulose columnar Nacre-like materials with a site-specific layered structure in the interior and a hierarchical columnar structure on the surface are prepared. The materials exhibit improved tensile strength, good chemical stability in seawater, superior resistance to sand-grain impingement, and robust underwater low-adhesive superoleophobicity.
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Nacre inspired integrated strong and tough reduced graphene oxide poly acrylic acid nanocomposites
Nanoscale, 2016Co-Authors: Sijie Wan, Lei Jiang, Jingsong Peng, Yuzun Fan, Qunfeng ChengAbstract:Inspired by the relationship between interface interactions and the high performance mechanical properties of Nacre, a strong and tough Nacre-inspired nanocomposite was demonstrated based on graphene oxide (GO) and polyacrylic acid (PAA) prepared via a vacuum-assisted filtration self-assembly process. The abundant hydrogen bonding between GO and PAA results in both high strength and toughness of the bioinspired nanocomposites, which are 2 and 3.3 times higher than that of pure reduced GO film, respectively. In addition, the effect of environmental relative humidity on the mechanical properties of bioinspired nanocomposites is also investigated, and is consistent with previous theoretical predictions. Moreover, this Nacre-inspired nanocomposite also displays high electrical conductivity of 108.9 S cm(-1). These excellent physical properties allow this type of Nacre-inspired nanocomposite to be used in many applications, such as flexible electrodes, aerospace applications, and artificial muscles etc. This Nacre-inspired strategy also opens an avenue for constructing integrated high performance graphene-based nanocomposites in the near future.
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use of synergistic interactions to fabricate strong tough and conductive artificial Nacre based on graphene oxide and chitosan
ACS Nano, 2015Co-Authors: Sijie Wan, Lei Jiang, Jingsong Peng, Qunfeng ChengAbstract:Graphene is the strongest and stiffest material, leading to the development of promising applications in many fields. However, the assembly of graphene nanosheets into macrosized nanocomposites for practical applications remains a challenge. Nacre in its natural form sets the "gold standard" for toughness and strength, which serves as a guide to the assembly of graphene nanosheets into high-performance nanocomposites. Here we show the strong, tough, conductive artificial Nacre based on graphene oxide through synergistic interactions of hydrogen and covalent bonding. Tensile strength and toughness was 4 and 10 times higher, respectively, than that of natural Nacre. The exceptional integrated strong and tough artificial Nacre has promising applications in aerospace, artificial muscle, and tissue engineering, especially for flexible supercapacitor electrodes due to its high electrical conductivity. The use of synergistic interactions is a strategy for the development of high-performance nanocomposites.
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bioinspired hierarchical alumina graphene oxide poly vinyl alcohol artificial Nacre with optimized strength and toughness
ACS Applied Materials & Interfaces, 2015Co-Authors: Jinrong Wang, Jianfeng Wang, Jinliang Qiao, Ying Zhu, Lei JiangAbstract:Due to hierarchical organization of micro- and nanostructures, natural Nacre exhibits extraordinary strength and toughness, and thus provides a superior model for the design and fabrication of high-performance artificial composite materials. Although great progress has been made in constructing layered composites by alternately stacking hard inorganic platelets and soft polymers, the real issue is that the excellent strength of these composites was obtained at the sacrifice of toughness. In this work, inspired by the layered aragonite microplatelets/chitin nanofibers–protein structure of natural Nacre, alumina microplatelets–graphene oxide nanosheets–poly(vinyl alcohol) (Al2O3/GO–PVA) artificial Nacre is successfully constructed through layer-by-layer bottom-up assembly, in which Al2O3 and GO–PVA act as “bricks” and “mortar”, respectively. The artificial Nacre has hierarchical “brick-and-mortar” structure and exhibits excellent strength (143 ± 13 MPa) and toughness (9.2 ± 2.7 MJ/m3), which are superior to...
Qunfeng Cheng - One of the best experts on this subject based on the ideXlab platform.
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Thermochromic Artificial Nacre Based on Montmorillonite
2017Co-Authors: Jingsong Peng, Lei Jiang, Yiren Cheng, Antoni P. Tomsia, Qunfeng ChengAbstract:Nacre-inspired nanocomposites have attracted a great deal of attention in recent years because of their special mechanical properties and universality of the underlying principles of materials engineering. The ability to respond to external stimuli will augment the high toughness and high strength of artificial Nacre-like composites and open new technological horizons for these materials. Herein, we fabricated robust artificial Nacre based on montmorillonite (MMT) that combines robustness with reversible thermochromism. Our artificial Nacre shows great potential in various fields such as aerospace and sensors and opens an avenue to fabricate artificial Nacre responsive to other external stimuli in the future
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super tough artificial Nacre based on graphene oxide via synergistic interface interactions of π π stacking and hydrogen bonding
Carbon, 2017Co-Authors: Qunfeng Cheng, Pingan Song, Qipeng Guo, Hao WangAbstract:Abstract Inspired by interfacial interactions of protein matrix and the crystal platelets in Nacre, herein, a super-tough artificial Nacre was produced through constructing the synergistic interface interactions of π-π interaction and hydrogen bonding between graphene oxide (GO) nanosheets and sulfonated styrene-ethylene/butylene-styrene copolymer synthesized with multifunctional benzene. The resultant GO-based artificial Nacre showed super-high toughness of 15.3 ± 2.5 MJ/m3, superior to natural Nacre and other GO-based nanocomposites. The ultra-tough property of the novel Nacre was attributed to synergistic effect of π-π stacking interactions and hydrogen bonding. This bioinspired synergistic toughening strategy opens a new avenue for constructing high performance GO-based nanocomposites in the near future.
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Nacre inspired integrated strong and tough reduced graphene oxide poly acrylic acid nanocomposites
Nanoscale, 2016Co-Authors: Sijie Wan, Lei Jiang, Jingsong Peng, Yuzun Fan, Qunfeng ChengAbstract:Inspired by the relationship between interface interactions and the high performance mechanical properties of Nacre, a strong and tough Nacre-inspired nanocomposite was demonstrated based on graphene oxide (GO) and polyacrylic acid (PAA) prepared via a vacuum-assisted filtration self-assembly process. The abundant hydrogen bonding between GO and PAA results in both high strength and toughness of the bioinspired nanocomposites, which are 2 and 3.3 times higher than that of pure reduced GO film, respectively. In addition, the effect of environmental relative humidity on the mechanical properties of bioinspired nanocomposites is also investigated, and is consistent with previous theoretical predictions. Moreover, this Nacre-inspired nanocomposite also displays high electrical conductivity of 108.9 S cm(-1). These excellent physical properties allow this type of Nacre-inspired nanocomposite to be used in many applications, such as flexible electrodes, aerospace applications, and artificial muscles etc. This Nacre-inspired strategy also opens an avenue for constructing integrated high performance graphene-based nanocomposites in the near future.
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use of synergistic interactions to fabricate strong tough and conductive artificial Nacre based on graphene oxide and chitosan
ACS Nano, 2015Co-Authors: Sijie Wan, Lei Jiang, Jingsong Peng, Qunfeng ChengAbstract:Graphene is the strongest and stiffest material, leading to the development of promising applications in many fields. However, the assembly of graphene nanosheets into macrosized nanocomposites for practical applications remains a challenge. Nacre in its natural form sets the "gold standard" for toughness and strength, which serves as a guide to the assembly of graphene nanosheets into high-performance nanocomposites. Here we show the strong, tough, conductive artificial Nacre based on graphene oxide through synergistic interactions of hydrogen and covalent bonding. Tensile strength and toughness was 4 and 10 times higher, respectively, than that of natural Nacre. The exceptional integrated strong and tough artificial Nacre has promising applications in aerospace, artificial muscle, and tissue engineering, especially for flexible supercapacitor electrodes due to its high electrical conductivity. The use of synergistic interactions is a strategy for the development of high-performance nanocomposites.
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learning from nature constructing integrated graphene based artificial Nacre
ACS Nano, 2015Co-Authors: Qunfeng Cheng, Jianli Duan, Qi Zhang, Lei JiangAbstract:Natural Nacre supplies a number of properties that can be used in designing high-performance bioinspired materials. Likewise, due to the extraordinary properties of graphene, a series of bioinspired graphene-based materials have recently been demonstrated. Compared to other approaches for constructing graphene-based materials, bioinspired concepts result in high-loading graphene, and the resultant high-performance graphene-based artificial Nacres demonstrate isotropic mechanical and electrical properties. In this Perspective, we describe how to construct integrated graphene-based artificial Nacre through the synergistic relationship between interface interactions and building blocks. These integrated graphene-based artificial Nacres show promising applications in many fields, such as aerospace, flexible supercapacitor electrodes, artificial muscle, and tissue engineering.
Frederic Marin - One of the best experts on this subject based on the ideXlab platform.
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Deep conservation of bivalve Nacre proteins highlighted by shell matrix proteomics of the Unionoida Elliptio complanata and Villosa lienosa.
Journal of the Royal Society Interface, 2017Co-Authors: Benjamin Marie, Sophie Berland, Arul Marie, Jaison Arivalagan, Lucrèce Mathéron, Gérard Bolbach, Frederic MarinAbstract:The formation of the molluscan shell Nacre is regulated to a large extent by a matrix of extracellular macromolecules that are secreted by the shell-forming tissue, the mantle. This so-called 'calcifying matrix' is a complex mixture of proteins, glycoproteins and polysaccharides that is assembled and occluded within the mineral phase during the calcification process. Better molecular-level characterization of the substances that regulate Nacre formation is still required. Notable advances in expressed tag sequencing of freshwater mussels, such as Elliptio complanata and Villosa lienosa, provide a pre-requisite to further characterize bivalve Nacre proteins by a proteomic approach. In this study, we have identified a total of 48 different proteins from the insoluble matrices of the Nacre, 31 of which are common to both E. complanata and V. lienosa A few of these proteins, such as PIF, MSI60, CA, shematrin-like, Kunitz-like, LamG, chitin-binding-containing proteins, together with A-, D-, G-, M- and Q-rich proteins, appear to be analogues, if not true homologues, of proteins previously described from the pearl oyster or the edible mussel Nacre matrices, thus forming a remarkable list of deeply conserved Nacre proteins. This work constitutes a comprehensive Nacre proteomic study of non-pteriomorphid bivalves that has enabled us to describe the molecular basis of a deeply conserved biomineralization toolkit among Nacreous shell-bearing bivalves, with regard to proteins associated with other shell microstructures, with those of other mollusc classes (gastropods, cephalopods) and, finally, with other lophotrochozoans (brachiopods).
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nanoscale assembly processes revealed in the nacroprismatic transition zone of pinna nobilis mollusc shells
Nature Communications, 2015Co-Authors: Robert Hovden, Frederic Marin, Stephan E Wolf, Megan E Holtz, David A Muller, Lara A EstroffAbstract:Intricate biomineralization processes in molluscs engineer hierarchical structures with meso-, nano- and atomic architectures that give the final composite material exceptional mechanical strength and optical iridescence on the macroscale. This multiscale biological assembly inspires new synthetic routes to complex materials. Our investigation of the prism-Nacre interface reveals nanoscale details governing the onset of Nacre formation using high-resolution scanning transmission electron microscopy. A wedge-polishing technique provides unprecedented, large-area specimens required to span the entire interface. Within this region, we find a transition from nanofibrillar aggregation to irregular early-Nacre layers, to well-ordered mature Nacre suggesting the assembly process is driven by aggregation of nanoparticles (∼50-80 nm) within an organic matrix that arrange in fibre-like polycrystalline configurations. The particle number increases successively and, when critical packing is reached, they merge into early-Nacre platelets. These results give new insights into Nacre formation and particle-accretion mechanisms that may be common to many calcareous biominerals.
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Pmarg-pearlin is a matrix protein involved in Nacre framework formation in the pearl oyster Pinctada margaritifera.
ChemBioChem, 2011Co-Authors: Caroline Montagnani, Yves Guéguen, Corinne Belliard, Frederic Marin, Elodie Fleury, Alexandre Tayale, Benjamin Marie, F. Riquet, Isabelle Zanella-cléon, David PiquemalAbstract:The shell of pearl oysters is organized in multiple layers of CaCO(3) crystallites packed together in an organic matrix. Relationships between the components of the organic matrix and mechanisms of Nacre formation currently constitute the main focus of research into biomineralization. In this study, we characterized the pearlin protein from the oyster Pinctada margaritifera (Pmarg); this shares structural features with other members of a matrix protein family, N14/N16/pearlin. Pmarg pearlin exhibits calcium- and chitin-binding properties. Pmarg pearlin transcripts are distinctively localized in the mineralizing tissue responsible for Nacre formation. More specifically, we demonstrate that Pmarg pearlin is localized within the interlamellar matrix of Nacre aragonite tablets. Our results support recent models for multidomain matrix protein involvement in Nacreous layer formation. We provide evidence here for the existence of a conserved family of Nacre-associated proteins in Pteriidae, and reassess the evolutionarily conserved set of biomineralization genes related to Nacre formation in this taxa.
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Acidic shell proteins of the Mediterranean fan mussel Pinna nobilis.
2011Co-Authors: Frederic Marin, Prabakaran Narayanappa, Sébastien MotreuilAbstract:In molluscs, the shell secretion process is controlled by a set of extracellular macromolecules collectively called the shell matrix. The shell matrix, which is produced by the mantle epithelial cells during mineralization, is predominantly composed of proteins, glycoproteins, acidic polysaccharides, and chitin that precisely regulate the deposition of calcium carbonate outside the mantle cells. In the present paper, we focus on the shell of Pinna nobilis, the giant Mediterranean fan mussel, usually considered as a model for studying molluscan biomineralization processes. P. nobilis exhibits indeed a nacro-prismatic shell, the outer layer of which is constituted of the so-called "regular simple calcitic prisms," according to Carter and Clark (1985). We review here the microstructural characteristics of the prisms and Nacre and the biochemical properties of their associated matrices. In particular, the calcitic prisms of P. nobilis are characterized by a cortege of unusually acidic intraprismatic proteins, while the ones of the Nacreous layer seem less acidic. A brief description of the molecular characterization of three acidic proteins, caspartin, calprismin and mucoperlin, is given. In particular, we show that extremely acidic intracrystalline proteins such as caspartin interact with calcium carbonate at different scales, from micrometric to crystal lattice levels.
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evolution of Nacre biochemistry and proteomics of the shell organic matrix of the cephalopod nautilus macromphalus
ChemBioChem, 2009Co-Authors: Benjamin Marie, Laurent Bedouet, Christian Milet, Frederic Marin, Arul Marie, Lionel Dubost, Gerard Alcaraz, Gilles LuquetAbstract:Matrix evolutions: We have biochemically characterized the Nacre matrix of the cephalopod Nautilus macromphalus, in part by a proteomic approach applied to the acetic acid-soluble and -insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Strikingly, most of the obtained partial sequences are entirely new, whereas a few correspond only partly with bivalvian Nacre proteins. Our findings shed new light on the macroevolution of Nacre matrix proteins. In mollusks, one of the most widely studied shell textures is Nacre, the lustrous aragonitic layer that constitutes the internal components of the shells of several bivalves, a few gastropods, and one cephalopod: the nautilus. Nacre contains a minor organic fraction, which displays a wide range of functions in relation to the biomineralization process. Here, we have biochemically characterized the Nacre matrix of the cephalopod Nautilus macromphalus. The acid-soluble matrix contains a mixture of polydisperse and discrete proteins and glycoproteins, which interact with the formation of calcite crystals. In addition, a few bind calcium ions. Furthermore, we have used a proteomic approach, which was applied to the acetic acid-soluble and -insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Our data demonstrate that the insoluble and soluble matrices, although different in their bulk monosaccharide and amino acid compositions, contain numerous shared peptides. Strikingly, most of the obtained partial sequences are entirely new. A few only partly match with bivalvian Nacre proteins. Our findings have implications for knowledge of the long-term evolution of molluskan Nacre matrices.
Paul C Southgate - One of the best experts on this subject based on the ideXlab platform.
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effects of nucleus position profile and arrangement on the quality of mabe pearls produced by the winged pearl oyster pteria penguin
Aquaculture, 2019Co-Authors: Sophie E Gordon, Siolaa Malimali, Ipek D Kurtboke, Max Wingfield, Paul C SouthgateAbstract:The position and arrangement of nuclei is the most important technical aspect of mabe pearl (half-pearl) production. This study examined the effects of nucleus arrangement, profile (height) and position, on quality, Nacre thickness and shape of mabe pearls produced by Pteria penguin. Oysters implanted with three nuclei produced a greater proportion of saleable mabe pearls with more regular shapes than oysters implanted with five nuclei. Use of low profile nuclei resulted in mabe pearls with increased Nacre thickness and produced mabe pearls of significantly higher quality, with more regular shapes than high profile nuclei. Nucleus position significantly influenced mabe pearl quality, Nacre thickness and shape. The posterior-ventral position of the left shell valve produced mabe pearls of the highest quality with the thickest Nacre and was the best location for mabe pearl culture. Based on the results of this study, it is recommended that P. penguin is implanted with a maximum of three nuclei to increase the production of regular-shaped mabe pearls, and that low profile nuclei are used to improve quality and Nacre thickness of mabe pearls produced in less favourable nucleus positions. An optimal nucleus arrangement for P. penguin of 130–150mm dorso-ventral height would include one high profile nucleus in the posterior-ventral position of the left shell plus additional low profile nuclei in both the anterior-ventral position of the left shell valve and, the center of the right shell. Based on the quality grading system used in this study, a minimum commercial Nacre thickness of 0.25mm is recommended for mabe pearl production using P. penguin.
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Using microradiography to assess Nacre thickness of mabé pearls: Technique suitability and insights
Aquaculture, 2018Co-Authors: Sophie E Gordon, Pranesh Kishore, Siolaa Malimali, 'ana 'akau'ola, Max Wingfield, Paul C SouthgateAbstract:Abstract Nacre thickness is a major factor influencing the quality and value of half-pearls (‘mabe’), yet accurate determination of Nacre thickness, in a non-destructive manner, is problematic. Microradiography is commonly used to measure the Nacre thickness of round pearls, however the suitability of this technique for mabe has not previously been assessed. Mabe were cultured in winged pearl oysters (Pteria penguin) for periods of 200 to 380 days to produce pearls with a range of Nacre thicknesses. The Nacre thickness of each pearl was quantified using microradiography and standard micrometer techniques. A strong, significant relationship was observed between measurements obtained using both techniques (R2 = 0.88, P ≤ 0.001). Microradiography produced defined, measureable images, with a resolution of ±0.04 mm, for mabe pearls with Nacre thicknesses between 0.1 and 1.3 mm. Mabe Nacre thickness and pearl quality were significantly influenced by the position of the pearl nucleus within the shell (T(95) = 7.14, P
Christian Milet - One of the best experts on this subject based on the ideXlab platform.
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evolution of Nacre biochemistry and proteomics of the shell organic matrix of the cephalopod nautilus macromphalus
ChemBioChem, 2009Co-Authors: Benjamin Marie, Laurent Bedouet, Christian Milet, Frederic Marin, Arul Marie, Lionel Dubost, Gerard Alcaraz, Gilles LuquetAbstract:Matrix evolutions: We have biochemically characterized the Nacre matrix of the cephalopod Nautilus macromphalus, in part by a proteomic approach applied to the acetic acid-soluble and -insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Strikingly, most of the obtained partial sequences are entirely new, whereas a few correspond only partly with bivalvian Nacre proteins. Our findings shed new light on the macroevolution of Nacre matrix proteins. In mollusks, one of the most widely studied shell textures is Nacre, the lustrous aragonitic layer that constitutes the internal components of the shells of several bivalves, a few gastropods, and one cephalopod: the nautilus. Nacre contains a minor organic fraction, which displays a wide range of functions in relation to the biomineralization process. Here, we have biochemically characterized the Nacre matrix of the cephalopod Nautilus macromphalus. The acid-soluble matrix contains a mixture of polydisperse and discrete proteins and glycoproteins, which interact with the formation of calcite crystals. In addition, a few bind calcium ions. Furthermore, we have used a proteomic approach, which was applied to the acetic acid-soluble and -insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Our data demonstrate that the insoluble and soluble matrices, although different in their bulk monosaccharide and amino acid compositions, contain numerous shared peptides. Strikingly, most of the obtained partial sequences are entirely new. A few only partly match with bivalvian Nacre proteins. Our findings have implications for knowledge of the long-term evolution of molluskan Nacre matrices.
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evolution of Nacre biochemistry and proteomics of the shell organic matrix of the cephalopod nautilus macromphalus
ChemBioChem, 2009Co-Authors: Benjamin Marie, Laurent Bedouet, Christian Milet, Frederic Marin, Arul Marie, Lionel Dubost, Gerard Alcaraz, Gilles LuquetAbstract:In mollusks, one of the most widely studied shell textures is Nacre, the lustrous aragonitic layer that constitutes the internal components of the shells of several bivalves, a few gastropods,and one cephalopod: the nautilus. Nacre contains a minor organic fraction, which displays a wide range of functions in relation to the biomineralization process. Here, we have biochemically characterized the Nacre matrix of the cephalopod Nautilus macromphalus. The acid-soluble matrix contains a mixture of polydisperse and discrete proteins and glycoproteins, which interact with the formation of calcite crystals. In addition, a few bind calcium ions. Furthermore, we have used a proteomic approach,which was applied to the acetic acid-soluble and -insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Our data demonstrate that the insoluble and soluble matrices, although different in their bulk monosaccharide and amino acid compositions, contain numerous shared peptides. Strikingly, most of the obtained partial sequences are entirely new. A few only partly match with bivalvian Nacre proteins.Our findings have implications for knowledge of the long-term evolution of molluskan Nacre matrices.
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bioactivity of Nacre water soluble organic matrix from the bivalve mollusk pinctada maxima in three mammalian cell types fibroblasts bone marrow stromal cells and osteoblasts
Comparative Biochemistry and Physiology B, 2002Co-Authors: Lucilia Mouries, Christian Milet, Mariajose Almeida, Sophie Berland, Evelyne LopezAbstract:Abstract In vivo and in vitro studies provide strong evidence of the osteogenic activity of Nacre obtained from Pinctada maxima. The in vitro studies indicate that diffusible factors from Nacre are involved in cell stimulation. The water-soluble matrix (WSM) was extracted from Nacre by a non-decalcifying process, and four fractions (SE1–SE4) were separated by SE-HPLC. Those fractions were tested in vitro on MRC5 fibroblasts. Alkaline phosphatase (ALP) activity was measured as a marker of osteoblastic differentiation. The anti-apoptotic protein Bcl-2 was also immunodetected in cultured osteoblasts from rat calvaria. WSM and fraction SE4 increased ALP activity. BMP-2 had the same effect on the cells as WSM and SE4. WSM greatly increased the amount of Bcl-2 in the cytoplasm and nucleus of osteoblasts. These in vitro studies support our initial hypothesis that Nacre organic matrix (WSM) of a bivalve mollusk contains signal-molecules that can stimulate the osteogenic pathway in mammalian cells that are targets for bone induction.
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soluble proteins of the Nacre of the giant oyster pinctada maxima and of the abalone haliotis tuberculata extraction and partial analysis of Nacre proteins
Comparative Biochemistry and Physiology B, 2001Co-Authors: Laurent Bedouet, Maria Jose Schuller, Christian Milet, Evelyne Lopez, Frederic Marin, Michel GiraudAbstract:Several proteins from Nacre of the oyster Pinctada maxima and the abalone Haliotis tuberculata were extracted and partly characterized. Proteins dispersed in aragonite were solubilized during demineralization with acetic acid whereas proteins adsorbed on conchiolin were extracted with sodium dodecyl sulfate and β-mercaptoethanol. The matrix of Pinctada maxima Nacre is composed of one main protein with an apparent molecular weight of 20 kDa (p20). This protein was found in the acetic acid soluble fraction of Nacre, as well as in the Laemmli-solubilized extract of conchiolin. In addition, the p20 solubilized with acetic acid can form oligomers made of 6 monomers linked together by disulfide bridges. The first N-terminal 21 amino acids of p20 were determined and no homology with known proteins was found. In Haliotis tuberculata Nacre, 5 main proteins were solubilized during demineralization and 3 glycoproteins were detected. Stains-all and Alcian blue staining revealed polyanionic proteins in the extracts isolated from Pinctada maxima and Haliotis tuberculata Nacre.
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characterization and quantification of chitosan extracted from Nacre of the abalone haliotis tuberculata and the oyster pinctada maxima
Marine Biotechnology, 2001Co-Authors: Frederic Zentz, Laurent Bedouet, Christian Milet, Maria Almeida, Evelyne Lopez, Michel GiraudAbstract:This study was performed to characterize and quantify chitosan by simple physicochemical methods (infrared spectroscopy and potentiometric measurements). These procedures were validated with well-characterized chitosan before being used to investigate chitosan in Nacre of the abalone Haliotis tuberculata and of the giant oyster Pinctada maxima. Potentiometric study revealed a chitosan extract from the Nacre of H. tuberculata with a degree of deacetylation of around 88% and an intrinsic pK of 6.5. According to infrared and potentiometric data, a low yield (η) of extraction was calculated (η= 0.064%). For experiments performed on the Nacre of P. maxima, and in spite of more stringent deacetylation conditions, results suggested that a chitin-protein complex (η= 0.053%) was isolated rather than chitosan.
