The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Mehmet Sarikaya - One of the best experts on this subject based on the ideXlab platform.
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Nonequilibrium synthesis and assembly of hybrid inorganic-protein nanostructures using an engineered DNA binding protein.
Journal of the American Chemical Society, 2005Co-Authors: Haixia Dai, Mehmet Sarikaya, Woo-seok Choe, Corrine K. Thai, Beth Traxler, François Baneyx, Daniel T. SchwartzAbstract:We show that a protein with no intrinsic inorganic synthesis activity can be endowed with the ability to control the formation of inorganic nanostructures under thermodynamically unfavorable (nonequilibrium) conditions, reproducing a key feature of Biological Hard-Tissue growth and assembly. The nonequilibrium synthesis of Cu(2)O nanoparticles is accomplished using an engineered derivative of the DNA-binding protein TraI in a room-temperature precursor electrolyte. The functional TraI derivative (TraIi1753::CN225) is engineered to possess a cysteine-constrained 12-residue Cu(2)O binding sequence, designated CN225, that is inserted into a permissive site in TraI. When TraIi1753::CN225 is included in the precursor electrolyte, stable Cu(2)O nanoparticles form, even though the concentrations of [Cu(+)] and [OH(-)] are at 5% of the solubility product (K(sp,Cu2O)). Negative control experiments verify that Cu(2)O formation is controlled by inclusion of the CN225 binding sequence. Transmission electron microscopy and electron diffraction reveal a core-shell structure for the nonequilibrium nanoparticles: a 2 nm Cu(2)O core is surrounded by an adsorbed protein shell. Quantitative protein adsorption studies show that the unexpected stability of Cu(2)O is imparted by the nanomolar surface binding affinity of TraIi1753::CN225 for Cu(2)O (K(d) = 1.2 x 10(-)(8) M), which provides favorable interfacial energetics (-45 kJ/mol) for the core-shell configuration. The protein shell retains the DNA-binding traits of TraI, as evidenced by the spontaneous organization of nanoparticles onto circular double-stranded DNA.
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Growth dynamics of red abalone shell: a biomimetic model
Materials Science and Engineering: C, 2000Co-Authors: Thomas J. A. Graham, Mehmet SarikayaAbstract:Abstract A model of shell formulation was developed in red abalone in which the nacre forms over the prismatic section. The model was based on roughness variations of the growing edge of the mollusc determined by atomic force microscopy. These variations were spatially distinguished and related to various sections of the shell, i.e., nacreous, prismatic, and the interface in between. With a diffusional growth model, it was estimated that for a relatively rough, zrms=(1.34±0.23) μm, surface, it will take (16.5±2.5) days for this surface to become flat, zrms=1 nm. This is the time it takes what was once a rough prismatic surface eventually smoothening to become a nacreous layer. For this time interval, the shell will have grown radially by approximately 1.2 mm. The smoothening coefficient, which measures the rate at which the nacre forms over the prismatic surface, was found to be es=(0.042±0.005) μm2/day. The model may have implications both for better understanding of Biological Hard Tissue formation and their biomimetic regeneration.
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A TEM study of the interface between organic matrix and aragonite in a Biological Hard Tissue, nacre
Proceedings annual meeting Electron Microscopy Society of America, 1992Co-Authors: Jun Liu, Katie E. Gunnison, Mehmet Sarikaya, Ilhan A. AksayAbstract:The interfacial structure between the organic and inorganic phases in Biological Hard Tissues plays an important role in controlling the growth and the mechanical properties of these materials. The objective of this work was to investigate these interfaces in nacre by transmission electron microscopy. The nacreous section of several different seashells -- abalone, pearl oyster, and nautilus -- were studied. Nacre is a laminated composite material consisting of CaCO3 platelets (constituting > 90 vol.% of the overall composite) separated by a thin organic matrix. Nacre is of interest to biomimetics because of its highly ordered structure and a good combination of mechanical properties. In this study, electron transparent thin sections were prepared by a low-temperature ion-beam milling procedure and by ultramicrotomy. To reveal structures in the organic layers as well as in the interfacial region, samples were further subjected to chemical fixation and labeling, or chemical etching. All experiments were performed with a Philips 430T TEM/STEM at 300 keV with a liquid Nitrogen sample holder.
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A Hierarchically Structured Model Composite: A Tem Study of the Hard Tissue of Red Abalone
MRS Online Proceedings Library, 1991Co-Authors: Jun Liu, Mehmet Sarikaya, Ilhan A. AksayAbstract:The structure and crystallography of the nacre of red abalone, Haliotis rufescens, was studied by transmission electron microscopy imaging and diffraction. We found that the nacre structure is based upon hierarchical {110} twinning in aragonite with the following organization: (i) first generation twins between platelets having incoherent boundaries, (ii) second generation twins between domains having coherent boundaries within a given platelet, and (iii) nanometer-scale third generation twins within domains. Since the aragonite platelets nucleate and grow as separate crystals, this long-range crystallographic relationship between the inorganic units of a Biological Hard Tissue indicates that the nucleation and growth process of crystals may be mediated by the organic matrix and that the organic template structure may also be long-range ordered. We propose a superlattice structure based on the possible twin variants and suggest that the organic matrix structure, or the arrangement of nucleation sites, is compatible with the superlattice. Multiple tiling based upon this superlattice allows all of the crystallographic and morphological platelet configurations observed in nacre.
Chenghuang Tang - One of the best experts on this subject based on the ideXlab platform.
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Novel β-type Zr–Mo–Ti alloys for Biological Hard Tissue replacements
Materials & Design, 2014Co-Authors: Li Nie, Yongzhong Zhan, Hao Liu, Chenghuang TangAbstract:Abstract In order to develop new biomaterials for Hard Tissue replacements, Zr–12Mo–xTi (x = 0, 3, 7 and 11, in at.%) alloys with required properties have been designed and prepared using vacuum arc melting method for the first time. Phase analysis and microstructural observation shows that all the as-cast samples consist of equiaxed β-Zr phase. Variations of lattice constants, volume and density of the Zr–12Mo–xTi alloys as a function of Ti content have been discussed. With the increase of Ti content, the microstructure is refined. The solid solution effect of the β-phase stabilization elements (i.e. Mo and Ti) predominantly determines the mechanical properties. These β-type Zr–12Mo–xTi alloys exhibit high compressive strength (1469–1584 MPa), high yield strength (1175–1375 MPa), high elastic energy (21–28 MJ/m3) and low Young’s modulus (32–35 GPa), together with plastic strain (11–25%). As the Zr–12Mo–xTi alloys are based on biocompatible elements, this good combination of biomechanical characteristics makes them potential biomedical materials for Hard Tissue replacements.
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In situ synthesized low modulus biomedical Zr-4Cu-xNb alloys.
Materials science & engineering. C Materials for biological applications, 2013Co-Authors: Li Nie, Yongzhong Zhan, Hao Liu, Chenghuang TangAbstract:In order to develop new biomaterials for Hard Tissue replacements, the Zr-4Cu-xNb (x=0, 0.3, 0.6 and 0.9) biomedical alloys with required properties were designed and prepared using vacuum arc melting method for the first time. Phase analysis and microstructure observation showed that all the as-cast Zr-4Cu-xNb samples consisted of α-Zr and Zr3Cu. In addition, the lamellar eutectoid is found near the grain boundary. These alloys exhibited moderate compressive strength (1150-1300 MPa), yield stress (750-1000 MPa), favorable plastic strain (19%-27%), high elastic energy (11 MJ/m(3)-16 MJ/m(3)) and low Young's modulus (25GPa-31GPa). This good combination of mechanical properties indicates them potential biomedical materials for Biological Hard Tissue replacements.
C. M. St. John - One of the best experts on this subject based on the ideXlab platform.
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Biomimetic Lithography and Deposition Kinetics of Iron Oxyhydroxide Thin Films
MRS Online Proceedings Library, 1993Co-Authors: Peter C. Rieke, Laurie L Wood, Mark H Engelhard, Gerald E Fryxell, D.r. Baer, Barbara J. Tarasevich, Brian D. Marsh, Lin Song, C. M. St. JohnAbstract:Heterogeneous nucleation and crystal growth on protein substrates are critical steps in Biological Hard Tissue formation. Self assembled monolayers can be derivatized with various organic functional groups to mimic the “nucleation proteins” for induction of mineral growth. Studies of nucleation and growth on SAMs can provide a better understanding of biomineralization and can also form the basis of a superior thin film deposition process. We demonstrate that micron-scale, electron and ion beam, lithographic techniques can be used to pattern SAMs with functional organic groups that either inhibit or promote mineral deposition. Patterned films of iron oxyhydroxide were deposited on the areas patterned with nucleation sites. Studies of the deposition kinetic of these films show that the surface indeed induces heterogeneous nucleation and that film formation does not occur via absorption of polymers or colloidal material formed homogeneously in solution. The nucleus interfacial free energy was calculated to be 88 mJ/m^2 on a SAM surface composed entirely of sulfonate groups.
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Biomimetic lithography and deposition kinetics of iron oxyhydroxide thin films
MRS Proceedings, 1993Co-Authors: Peter C. Rieke, B.m. Marsh, Laurie L Wood, Mark H Engelhard, Gerald E Fryxell, D.r. Baer, Barbara J. Tarasevich, C. M. St. JohnAbstract:Heterogeneous nucleation and crystal growth on functionalized organic substrates is a critical step in Biological Hard Tissue formation. Self assembled monolayers can be derivatized with various organic functional groups to mimic the ``nucleation proteins`` for induction of mineral growth. Studies of nucleation and growth on SAMs can provide a better understanding of biomineralization and can also form the basis of a superior thin film deposition process. We demonstrate that micron-scale, electron and ion beam, lithographic techniques can be used to pattern SAMs with functional organic groups that either inhibit or promote mineral deposition. Patterned films of iron oxyhydroxide were deposited on the areas patterned with nucleation sites. Studies of the deposition kinetic of these films show that indeed the surface induces heterogeneous nucleation and that film formation does not occur via absorption of polymers or colloidal material formed homogeneously in solution. The nucleus interfacial free energy was calculated to be 24 mJ/m2 on a SAM surface composed entirely of sulfonate groups.
Li Nie - One of the best experts on this subject based on the ideXlab platform.
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Novel β-type Zr–Mo–Ti alloys for Biological Hard Tissue replacements
Materials & Design, 2014Co-Authors: Li Nie, Yongzhong Zhan, Hao Liu, Chenghuang TangAbstract:Abstract In order to develop new biomaterials for Hard Tissue replacements, Zr–12Mo–xTi (x = 0, 3, 7 and 11, in at.%) alloys with required properties have been designed and prepared using vacuum arc melting method for the first time. Phase analysis and microstructural observation shows that all the as-cast samples consist of equiaxed β-Zr phase. Variations of lattice constants, volume and density of the Zr–12Mo–xTi alloys as a function of Ti content have been discussed. With the increase of Ti content, the microstructure is refined. The solid solution effect of the β-phase stabilization elements (i.e. Mo and Ti) predominantly determines the mechanical properties. These β-type Zr–12Mo–xTi alloys exhibit high compressive strength (1469–1584 MPa), high yield strength (1175–1375 MPa), high elastic energy (21–28 MJ/m3) and low Young’s modulus (32–35 GPa), together with plastic strain (11–25%). As the Zr–12Mo–xTi alloys are based on biocompatible elements, this good combination of biomechanical characteristics makes them potential biomedical materials for Hard Tissue replacements.
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In situ synthesized low modulus biomedical Zr-4Cu-xNb alloys.
Materials science & engineering. C Materials for biological applications, 2013Co-Authors: Li Nie, Yongzhong Zhan, Hao Liu, Chenghuang TangAbstract:In order to develop new biomaterials for Hard Tissue replacements, the Zr-4Cu-xNb (x=0, 0.3, 0.6 and 0.9) biomedical alloys with required properties were designed and prepared using vacuum arc melting method for the first time. Phase analysis and microstructure observation showed that all the as-cast Zr-4Cu-xNb samples consisted of α-Zr and Zr3Cu. In addition, the lamellar eutectoid is found near the grain boundary. These alloys exhibited moderate compressive strength (1150-1300 MPa), yield stress (750-1000 MPa), favorable plastic strain (19%-27%), high elastic energy (11 MJ/m(3)-16 MJ/m(3)) and low Young's modulus (25GPa-31GPa). This good combination of mechanical properties indicates them potential biomedical materials for Biological Hard Tissue replacements.
Peter C. Rieke - One of the best experts on this subject based on the ideXlab platform.
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Biomimetic Lithography and Deposition Kinetics of Iron Oxyhydroxide Thin Films
MRS Online Proceedings Library, 1993Co-Authors: Peter C. Rieke, Laurie L Wood, Mark H Engelhard, Gerald E Fryxell, D.r. Baer, Barbara J. Tarasevich, Brian D. Marsh, Lin Song, C. M. St. JohnAbstract:Heterogeneous nucleation and crystal growth on protein substrates are critical steps in Biological Hard Tissue formation. Self assembled monolayers can be derivatized with various organic functional groups to mimic the “nucleation proteins” for induction of mineral growth. Studies of nucleation and growth on SAMs can provide a better understanding of biomineralization and can also form the basis of a superior thin film deposition process. We demonstrate that micron-scale, electron and ion beam, lithographic techniques can be used to pattern SAMs with functional organic groups that either inhibit or promote mineral deposition. Patterned films of iron oxyhydroxide were deposited on the areas patterned with nucleation sites. Studies of the deposition kinetic of these films show that the surface indeed induces heterogeneous nucleation and that film formation does not occur via absorption of polymers or colloidal material formed homogeneously in solution. The nucleus interfacial free energy was calculated to be 88 mJ/m^2 on a SAM surface composed entirely of sulfonate groups.
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Biomimetic lithography and deposition kinetics of iron oxyhydroxide thin films
MRS Proceedings, 1993Co-Authors: Peter C. Rieke, B.m. Marsh, Laurie L Wood, Mark H Engelhard, Gerald E Fryxell, D.r. Baer, Barbara J. Tarasevich, C. M. St. JohnAbstract:Heterogeneous nucleation and crystal growth on functionalized organic substrates is a critical step in Biological Hard Tissue formation. Self assembled monolayers can be derivatized with various organic functional groups to mimic the ``nucleation proteins`` for induction of mineral growth. Studies of nucleation and growth on SAMs can provide a better understanding of biomineralization and can also form the basis of a superior thin film deposition process. We demonstrate that micron-scale, electron and ion beam, lithographic techniques can be used to pattern SAMs with functional organic groups that either inhibit or promote mineral deposition. Patterned films of iron oxyhydroxide were deposited on the areas patterned with nucleation sites. Studies of the deposition kinetic of these films show that indeed the surface induces heterogeneous nucleation and that film formation does not occur via absorption of polymers or colloidal material formed homogeneously in solution. The nucleus interfacial free energy was calculated to be 24 mJ/m2 on a SAM surface composed entirely of sulfonate groups.