Home About us Contact
|
Home About us Contact | ||
|
|
||
Diamond Surface (diamond + surface)
Selected AbstractsDiamond Transistor Array for Extracellular Recording From Electrogenic CellsADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Markus Dankerl Abstract The transduction of electric signals from cells to electronic devices is mandatory for medical applications such as neuroprostheses and fundamental research on communication in neuronal networks. Here, the use of diamond with its advantages for biological applications as a new material for biohybrid devices for the detection of cell signals is investigated. Using the surface conductivity of hydrogen-terminated single-crystalline diamond substrates, arrays of solution-gate field-effect transistors were fabricated. The characterization of the transistors reveals a good stability in electrolyte solutions for at least 7 days. On these devices, cardiomyocyte-like HL-1 cells as well as human embryonic kidney cells (HEK293), which were stably transfected with potassium channels, are cultured. Both types of cells show healthy growth and good adhesion to the substrate. The diamond transistors are used to detect electrical signals from both types of cells by recording the extracellular potential. For the HL-1 cells, the shape of action potentials can be resolved and the propagation of the signal across the cell layer is visible. Potassium currents of HEK293 cells are activated with the patch-clamp technique in voltage-clamp mode and simultaneously measured with the field-effect transistors. The ion sensitivity of the diamond surface enables the detection of released potassium ions accumulated in the cleft between transistor and cell. [source] Carbon nanodots made on diamond surface by focused ion beamPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2006Alexander M. Zaitsev Abstract Carbon nanodots were made on the polished surface of a single crystal CVD diamond by a focused 30 keV Ga+ ion beam. The electrical conductance via the nanodots was measured in two types of structures: single nanodots embedded in the gaps of broken carbon nanowires and linear chains of nanodots. Changes of the conductance with annealing temperature allow to make the conclusion that the size of the electrically conductive area of the nanodots increases from a few nanometers to 20 nm after annealing from 500 to 1000 °C. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Hydrogenation and oxygenation of the (100) diamond surface and the consequences for transfer dopingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2005S. J. Sque Abstract Ab initio density-functional-theory calculations have been performed to determine the structural and electronic properties of the (100) diamond surface with various hydrogen and oxygen terminations. Total energies indicate that an ,OH-terminated surface is favoured over an oxygenated surface plus gas-phase hydrogen. Ionisation potentials and electron affinities (EAs) are reported for the different systems, and the distinction is made between bulk- and surface-related properties. A first-order correction is used to offer estimated surface EAs. A negative bulk EA is found for surfaces terminated with ,H and ,OH groups, although many surfaces have deep traps which can act as positive EA in the absence of band bending. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Simulation of dc conductance of two-dimensional heterogeneous system: application to carbon wires made by ion irradiation on polycrystalline diamondPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2006N. A. Poklonski Abstract A percolation model of two-dimensional heterogeneous system composed of two conductive phases and a method for calculating the macroscopic electric conductance of such a system in direct current regime is proposed. The parameters of the model are its geometrical dimensions, the conductance of the two phases and the relative fractions of the phases in the system. The model satisfactorily describes the non-linear dependence on width of conductance of the carbon nano- and microwires made on polycrystalline diamond surface by focused ion beam irradiation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Chemical Bonding of Fullerene and Fluorinated Fullerene on Bare and Hydrogenated DiamondCHEMPHYSCHEM, Issue 9 2008Ti Ouyang Abstract We investigate the interface between a C60 fullerite film, C60F36, and diamond (100) by using core-level photoemission spectroscopy, cyclic voltammetry (CV), and high-resolution electron energy loss spectroscopy (HREELS). We show that C60 can be covalently bonded to reconstructed C(100)-2×1 and that the bonded interface is sufficiently robust to exhibit characteristic C60 redox peaks in solution. The bare diamond surface can be passivated against oxidation and hydrogenation by covalently bound C60. However, C60F36 is not as stable as C60 and desorbs below 300,°C (the latter species being stable up to 500,°C on the diamond surface). Neither C60 fullerite nor C60F36 form reactive interfaces on the hydrogenated surface,they both desorb below 300,°C. The surface transfer doping process of hydrogenated diamond by C60F36 is the most evident one among all the adsorbate systems studied (with a coverage-dependent band bending induced by C60F36). [source] Using Scanning Electrochemical Microscopy to Determine the Doping Level and the Flatband Potential of Boron-Doped Diamond ElectrodesCHEMPHYSCHEM, Issue 1 2006Jérôme Chane-Tune Dr. A new approach for determining the doping level (NA) and the flatband potential () of electrochemically activated boron-doped diamond electrodes is presented. Scanning electrochemical microscopy is used to monitor an electrode's approach to a diamond surface (see figure): The obtained approach curves are then used to determine NA (8.3×1019 B,cm,3) and (0.654 V vs. Ag/AgCl). [source] Diamond growth during ultrahigh-pressure metamorphism of the Kokchetav Massif, northern KazakhstanISLAND ARC, Issue 3 2000K. De Corte Abstract Characteristic features of in situ diamonds can be used to retrace diamond formation during ultrahigh pressure (UHP) metamorphism of the Kokchetav Massif, Kazakhstan. These features include the nitrogen aggregation state in diamond, dissolution features observed on diamond surfaces, and the carbon and nitrogen isotopic composition of the diamonds. The minerals in which the diamonds are included provide additional information and support the view that at least some of the Kokchetav microdiamonds are the products of prograde or peak UHP metamorphism. The coexistence of diamond and graphite is evaluated within this framework. [source] Transparent diamond-on-glass micro-electrode arrays for ex-vivo neuronal studyPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2008M. Bonnauron Abstract We report on the fabrication of high aspect ratio diamond Micro Electrode Arrays (MEAs) grown on silicon as well as on glass substrates using an optimised nanoseeding technique and Bias Enhanced Nucleation (BEN). Such MEA systems combine high electrode reactivity and high electrical current injection limits with resiliency, biocompatibility and optical transparency of diamond surfaces. We present the technological steps for the fabrication of 2D as well as 3D diamond microelectrode arrays. The patterning issues involve the use of detonation nanodiamond particles (DND). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microscopic diagnostics of DNA molecules on mono-crystalline diamondPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2007Bohuslav Rezek Abstract Detailed data about deoxyribonucleic acid (DNA) attachment, arrangement, density and functionality on mono-crystalline diamond surfaces are obtained by direct measurements in electrolytic solutions using fluorescence microscopy and atomic force microscopy in various regimes (oscillating, contact, phase, and surface potential imaging) and by fitting the data into a microscopic geometrical model of DNA. DNA is immobilized on undoped and boron-doped diamonds with hydrogen and oxygen surface terminations which were functionalized by aminodecene and nitrofenyl linker molecules. The data show that, except photochemically processed oxidized diamond surfaces, the DNA molecules are covalently linked to diamond in a 65,92 Å thin and highly dense layers (6 × 1012 molecules/cm2) with sub-nanometer intermolecular spacing and a strong tilt of 31° with respect to the surface. Ordering of these DNA layers shows only a weak (<10%) response to a change of buffer salinity in the range of 1,300 mM. The data are discussed with view to biosensor applications. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Long-term adsorption of fetal bovine serum on H/O-terminated diamond studied in situ by atomic force microscopyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009E. Ukraintsev Abstract We investigate adhesion of fetal bovine serum (FBS) on diamond surfaces which have alternating H/O-terminated surface patterns of 30,µm width prepared by hydrogen and oxygen plasma. The samples are immersed into 15% FBS in McCoy's 5A supporting medium and characterized by in situ atomic force microscopy (AFM) during 6 days of adsorption. Within the first day, 2,4,nm primary layer is formed on both H-/O-terminated surfaces. After 6 days, we observe 17,±,5,nm FBS layer on O-terminated surface and 35,±,5,nm layer on H-terminated surface. Adhesion of the primary and secondary layer is weaker on H-terminated surface. We present a model of FBS protein layers on H-/O-terminated diamond and we discuss implications for a preferential cell growth on O-terminated diamond. We also show that the preferential cell growth is not affected by the long-term FBS pre-adsorption. [source] | ||||||||||