Publications
2011 |
Ang, Priscilla Kailian; Li, Ang; Jaiswal, Manu; Wang, Yu; Hou, Han Wei; Thong, John T L; Lim, Chwee Teck; Loh, Kian Ping Flow Sensing of Single Cell by Graphene Transistor in a Microfluidic Channel Journal Article NANO LETTERS, 11 (12), pp. 5240-5246, 2011, ISSN: 1530-6984. @article{ISI:000297950200024, title = {Flow Sensing of Single Cell by Graphene Transistor in a Microfluidic Channel}, author = {Priscilla Kailian Ang and Ang Li and Manu Jaiswal and Yu Wang and Han Wei Hou and John T L Thong and Chwee Teck Lim and Kian Ping Loh}, doi = {10.1021/nl202579k}, times_cited = {0}, issn = {1530-6984}, year = {2011}, date = {2011-12-01}, journal = {NANO LETTERS}, volume = {11}, number = {12}, pages = {5240-5246}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {The electronic properties of graphene are strongly influenced by electrostatic forces arising from long-range charge scatterers and by changes in the local dielectric environment. This makes graphene extremely sensitive to the surface charge density of cells interfacing with it Here, we developed a graphene transistor array integrated with microfluidic flow cytometry for the "flow-catch-release" sensing of malaria-infected red blood cells at the single-cell level. Malaria-infected red blood cells induce highly sensitive capacitively coupled changes in the conductivity of graphene. Together with the characteristic conductance dwell times, specific microscopic information about the disease state can be obtained.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The electronic properties of graphene are strongly influenced by electrostatic forces arising from long-range charge scatterers and by changes in the local dielectric environment. This makes graphene extremely sensitive to the surface charge density of cells interfacing with it Here, we developed a graphene transistor array integrated with microfluidic flow cytometry for the "flow-catch-release" sensing of malaria-infected red blood cells at the single-cell level. Malaria-infected red blood cells induce highly sensitive capacitively coupled changes in the conductivity of graphene. Together with the characteristic conductance dwell times, specific microscopic information about the disease state can be obtained. |
Ferreira, Aires; Viana-Gomes, J; Bludov, Yu. V; Pereira, V; Peres, N M R; Neto, Castro A H Faraday effect in graphene enclosed in an optical cavity and the equation of motion method for the study of magneto-optical transport in solids Journal Article PHYSICAL REVIEW B, 84 (23), 2011, ISSN: 2469-9950. @article{ISI:000297551600027, title = {Faraday effect in graphene enclosed in an optical cavity and the equation of motion method for the study of magneto-optical transport in solids}, author = {Aires Ferreira and J Viana-Gomes and Yu. V Bludov and V Pereira and N M R Peres and Castro A H Neto}, doi = {10.1103/PhysRevB.84.235410}, times_cited = {6}, issn = {2469-9950}, year = {2011}, date = {2011-12-01}, journal = {PHYSICAL REVIEW B}, volume = {84}, number = {23}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {We show that by enclosing graphene in an optical cavity, giant Faraday rotations in the infrared regime are generated and measurable Faraday rotation angles in the visible range become possible. Explicit expressions for the Hall steps of the Faraday rotation angle are given for relevant regimes. In the context of this problem we develop an equation of motion (EOM) method for calculation of the magneto-optical properties of metals and semiconductors. It is shown that properly regularized EOM solutions are fully equivalent to the Kubo formula.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We show that by enclosing graphene in an optical cavity, giant Faraday rotations in the infrared regime are generated and measurable Faraday rotation angles in the visible range become possible. Explicit expressions for the Hall steps of the Faraday rotation angle are given for relevant regimes. In the context of this problem we develop an equation of motion (EOM) method for calculation of the magneto-optical properties of metals and semiconductors. It is shown that properly regularized EOM solutions are fully equivalent to the Kubo formula. |
Lee, Dong Su; Riedl, Christian; Beringer, Thomas; Neto, Castro A H; von Klitzing, Klaus; Starke, Ulrich; Smet, Jurgen H Quantum Hall Effect in Twisted Bilayer Graphene Journal Article PHYSICAL REVIEW LETTERS, 107 (21), 2011, ISSN: 0031-9007. @article{ISI:000297136400005, title = {Quantum Hall Effect in Twisted Bilayer Graphene}, author = {Dong Su Lee and Christian Riedl and Thomas Beringer and Castro A H Neto and Klaus von Klitzing and Ulrich Starke and Jurgen H Smet}, doi = {10.1103/PhysRevLett.107.216602}, times_cited = {5}, issn = {0031-9007}, year = {2011}, date = {2011-11-16}, journal = {PHYSICAL REVIEW LETTERS}, volume = {107}, number = {21}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {We address the quantum Hall behavior in twisted bilayer graphene transferred from the C face of SiC. The measured Hall conductivity exhibits the same plateau values as for a commensurate Bernal bilayer. This implies that the eightfold degeneracy of the zero energy mode is topologically protected despite rotational disorder as recently predicted. In addition, an anomaly appears. The densities at which these plateaus occur show a magnetic field dependent offset. It suggests the existence of a pool of localized states at low energy, which do not count towards the degeneracy of the lowest band Landau levels. These states originate from an inhomogeneous spatial variation of the interlayer coupling.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We address the quantum Hall behavior in twisted bilayer graphene transferred from the C face of SiC. The measured Hall conductivity exhibits the same plateau values as for a commensurate Bernal bilayer. This implies that the eightfold degeneracy of the zero energy mode is topologically protected despite rotational disorder as recently predicted. In addition, an anomaly appears. The densities at which these plateaus occur show a magnetic field dependent offset. It suggests the existence of a pool of localized states at low energy, which do not count towards the degeneracy of the lowest band Landau levels. These states originate from an inhomogeneous spatial variation of the interlayer coupling. |
Fei, Zhe; Andreev, Gregory O; Bao, Wenzhong; Zhang, Lingfeng M; McLeod, Alexander S; Wang, Chen; Stewart, Margaret K; Zhao, Zeng; Dominguez, Gerardo; Thiemens, Mark; Fogler, Michael M; Tauber, Michael J; Castro-Neto, Antonio H; Lau, Chun Ning; Keilmann, Fritz; Basov, Dimitri N Infrared Nanoscopy of Dirac Plasmons at the Graphene-SiO2 Interface Journal Article NANO LETTERS, 11 (11), pp. 4701-4705, 2011, ISSN: 1530-6984. @article{ISI:000296674700036, title = {Infrared Nanoscopy of Dirac Plasmons at the Graphene-SiO_{2} Interface}, author = {Zhe Fei and Gregory O Andreev and Wenzhong Bao and Lingfeng M Zhang and Alexander S McLeod and Chen Wang and Margaret K Stewart and Zeng Zhao and Gerardo Dominguez and Mark Thiemens and Michael M Fogler and Michael J Tauber and Antonio H Castro-Neto and Chun Ning Lau and Fritz Keilmann and Dimitri N Basov}, doi = {10.1021/nl202362d}, times_cited = {0}, issn = {1530-6984}, year = {2011}, date = {2011-11-01}, journal = {NANO LETTERS}, volume = {11}, number = {11}, pages = {4701-4705}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac fermions in graphene. This is achieved by confining mid-IR radiation at the apex of a nanoscale tip: an approach yielding 2 orders of magnitude increase in the value of in-plane component of incident wavevector q compared to free space propagation. At these high wavevectors, the Dirac plasmon is found to dramatically enhance the near-field interaction with mid-IR surface phonons of SiO2 substrate. Our data augmented by detailed modeling establish graphene as a new medium supporting plasmonic effects that can be controlled by gate voltage.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac fermions in graphene. This is achieved by confining mid-IR radiation at the apex of a nanoscale tip: an approach yielding 2 orders of magnitude increase in the value of in-plane component of incident wavevector q compared to free space propagation. At these high wavevectors, the Dirac plasmon is found to dramatically enhance the near-field interaction with mid-IR surface phonons of SiO2 substrate. Our data augmented by detailed modeling establish graphene as a new medium supporting plasmonic effects that can be controlled by gate voltage. |
Rodrigues, J N B; Goncalves, P A D; Rodrigues, N F G; Ribeiro, R M; dos Santos, Lopes J M B; Peres, N M R Zigzag graphene nanoribbon edge reconstruction with Stone-Wales defects Journal Article PHYSICAL REVIEW B, 84 (15), 2011, ISSN: 1098-0121. @article{ISI:000296290000014, title = {Zigzag graphene nanoribbon edge reconstruction with Stone-Wales defects}, author = {J N B Rodrigues and P A D Goncalves and N F G Rodrigues and R M Ribeiro and Lopes J M B dos Santos and N M R Peres}, doi = {10.1103/PhysRevB.84.155435}, times_cited = {0}, issn = {1098-0121}, year = {2011}, date = {2011-10-18}, journal = {PHYSICAL REVIEW B}, volume = {84}, number = {15}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {In this paper, we study zigzag graphene nanoribbons with edges reconstructed with Stone-Wales defects, by means of an empirical (first-neighbor) tight-binding method, with parameters determined by ab initio calculations of very narrow ribbons. We explore the characteristics of the electronic band structure with a focus on the nature of edge states. Edge reconstruction allows the appearance of a new type of edge states. They are dispersive, with nonzero amplitudes in both sublattices; furthermore, the amplitudes have two components that decrease with different decay lengths with the distance from the edge; at the Dirac points one of these lengths diverges, whereas the other remains finite, of the order of the lattice parameter. We trace this curious effect to the doubling of the unit cell along the edge, brought about by the edge reconstruction. In the presence of a magnetic field, the zero-energy Landau level is no longer degenerate with edge states as in the case of the pristine zigzag ribbon.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this paper, we study zigzag graphene nanoribbons with edges reconstructed with Stone-Wales defects, by means of an empirical (first-neighbor) tight-binding method, with parameters determined by ab initio calculations of very narrow ribbons. We explore the characteristics of the electronic band structure with a focus on the nature of edge states. Edge reconstruction allows the appearance of a new type of edge states. They are dispersive, with nonzero amplitudes in both sublattices; furthermore, the amplitudes have two components that decrease with different decay lengths with the distance from the edge; at the Dirac points one of these lengths diverges, whereas the other remains finite, of the order of the lattice parameter. We trace this curious effect to the doubling of the unit cell along the edge, brought about by the edge reconstruction. In the presence of a magnetic field, the zero-energy Landau level is no longer degenerate with edge states as in the case of the pristine zigzag ribbon. |
Rappoport, T G; Godoy, M; Uchoa, B; Santos, Dos R R; Neto, Castro A H Magnetic exchange mechanism for electronic gap opening in graphene Journal Article EPL, 96 (2), 2011, ISSN: 0295-5075. @article{ISI:000295974600033, title = {Magnetic exchange mechanism for electronic gap opening in graphene}, author = {T G Rappoport and M Godoy and B Uchoa and Dos R R Santos and Castro A H Neto}, doi = {10.1209/0295-5075/96/27010}, times_cited = {0}, issn = {0295-5075}, year = {2011}, date = {2011-10-01}, journal = {EPL}, volume = {96}, number = {2}, publisher = {IOP PUBLISHING LTD}, address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, abstract = {We show within a local self-consistent mean-field treatment that a random distribution of magnetic adatoms can open a robust gap in the electronic spectrum of graphene. The electronic gap results from the localization of the charge carriers that arises from the interplay between the graphene sublattice structure and the exchange interaction between the adatoms. The size of the gap depends on the strength of the exchange interaction between carriers and localized spins and can be controlled by both temperature and external magnetic field. Furthermore, we show that an external magnetic field creates an imbalance of spin-up and spin-down carriers at the Fermi level, making doped graphene suitable for spin injection and other spintronic applications. Copyright (C) EPLA, 2011}, keywords = {}, pubstate = {published}, tppubtype = {article} } We show within a local self-consistent mean-field treatment that a random distribution of magnetic adatoms can open a robust gap in the electronic spectrum of graphene. The electronic gap results from the localization of the charge carriers that arises from the interplay between the graphene sublattice structure and the exchange interaction between the adatoms. The size of the gap depends on the strength of the exchange interaction between carriers and localized spins and can be controlled by both temperature and external magnetic field. Furthermore, we show that an external magnetic field creates an imbalance of spin-up and spin-down carriers at the Fermi level, making doped graphene suitable for spin injection and other spintronic applications. Copyright (C) EPLA, 2011 |
Santos, Jaime E; Peres, Nuno M R; dos Santos, Joao Lopes M B; Neto, Antonio Castro H Electronic doping of graphene by deposited transition metal atoms Journal Article PHYSICAL REVIEW B, 84 (8), 2011, ISSN: 2469-9950. @article{ISI:000294325400014, title = {Electronic doping of graphene by deposited transition metal atoms}, author = {Jaime E Santos and Nuno M R Peres and Joao Lopes M B dos Santos and Antonio Castro H Neto}, doi = {10.1103/PhysRevB.84.085430}, times_cited = {0}, issn = {2469-9950}, year = {2011}, date = {2011-08-26}, journal = {PHYSICAL REVIEW B}, volume = {84}, number = {8}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {We perform a phenomenological analysis of the problem of the electronic doping of a graphene sheet by deposited transition metal atoms, which aggregate in clusters. The sample is placed in a capacitor device such that the electronic doping of graphene can be varied by the application of a gate voltage and such that transport measurements can be performed via the application of a (much smaller) voltage along the graphene sample, as reported in the work of Pi et al. [Phys. Rev. B 80, 075406 (2009)]. The analysis allows us to explain the thermodynamic properties of the device, such as the level of doping of graphene and the ionization potential of the metal clusters, in terms of the chemical interaction between graphene and the clusters. We are also able, by modeling the metallic clusters as perfectly conducting spheres, to determine the scattering potential due to these clusters on the electronic carriers of graphene and hence the contribution of these clusters to the resistivity of the sample. The model presented is able to explain the measurements performed by Pi et al. on Pt-covered graphene samples at the lowest metallic coverages measured, and we also present a theoretical argument based on the above model that explains why significant deviations from such a theory are observed at higher levels of coverage.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We perform a phenomenological analysis of the problem of the electronic doping of a graphene sheet by deposited transition metal atoms, which aggregate in clusters. The sample is placed in a capacitor device such that the electronic doping of graphene can be varied by the application of a gate voltage and such that transport measurements can be performed via the application of a (much smaller) voltage along the graphene sample, as reported in the work of Pi et al. [Phys. Rev. B 80, 075406 (2009)]. The analysis allows us to explain the thermodynamic properties of the device, such as the level of doping of graphene and the ionization potential of the metal clusters, in terms of the chemical interaction between graphene and the clusters. We are also able, by modeling the metallic clusters as perfectly conducting spheres, to determine the scattering potential due to these clusters on the electronic carriers of graphene and hence the contribution of these clusters to the resistivity of the sample. The model presented is able to explain the measurements performed by Pi et al. on Pt-covered graphene samples at the lowest metallic coverages measured, and we also present a theoretical argument based on the above model that explains why significant deviations from such a theory are observed at higher levels of coverage. |
Neto, Castro A H; Novoselov, K New directions in science and technology: two-dimensional crystals Journal Article REPORTS ON PROGRESS IN PHYSICS, 74 (8), 2011, ISSN: 0034-4885. @article{ISI:000293225900001, title = {New directions in science and technology: two-dimensional crystals}, author = {Castro A H Neto and K Novoselov}, doi = {10.1088/0034-4885/74/8/082501}, times_cited = {0}, issn = {0034-4885}, year = {2011}, date = {2011-08-01}, journal = {REPORTS ON PROGRESS IN PHYSICS}, volume = {74}, number = {8}, publisher = {IOP PUBLISHING LTD}, address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, abstract = {Graphene is possibly one of the largest and fastest growing fields in condensed matter research. However, graphene is only one example in a large class of two-dimensional crystals with unusual properties. In this paper we briefly review the properties of graphene and look at the exciting possibilities that lie ahead.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Graphene is possibly one of the largest and fastest growing fields in condensed matter research. However, graphene is only one example in a large class of two-dimensional crystals with unusual properties. In this paper we briefly review the properties of graphene and look at the exciting possibilities that lie ahead. |
de Gail, R; Goerbig, M O; Guinea, F; Montambaux, G; Neto, Castro A H Topologically protected zero modes in twisted bilayer graphene Journal Article PHYSICAL REVIEW B, 84 (4), 2011, ISSN: 1098-0121. @article{ISI:000292825100016, title = {Topologically protected zero modes in twisted bilayer graphene}, author = {R de Gail and M O Goerbig and F Guinea and G Montambaux and Castro A H Neto}, doi = {10.1103/PhysRevB.84.045436}, times_cited = {0}, issn = {1098-0121}, year = {2011}, date = {2011-07-18}, journal = {PHYSICAL REVIEW B}, volume = {84}, number = {4}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {We show that a twisted graphene bilayer can reveal unusual topological properties at low energies, as a consequence of a Dirac-point splitting. These features rely on a symmetry analysis of the electron hopping between the two layers of graphene and we derive a simplified effective low-energy Hamiltonian which captures the essential topological properties of a twisted graphene bilayer. The corresponding Landau levels peculiarly reveal a degenerate zero-energy mode which cannot be lifted by strong magnetic fields.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We show that a twisted graphene bilayer can reveal unusual topological properties at low energies, as a consequence of a Dirac-point splitting. These features rely on a symmetry analysis of the electron hopping between the two layers of graphene and we derive a simplified effective low-energy Hamiltonian which captures the essential topological properties of a twisted graphene bilayer. The corresponding Landau levels peculiarly reveal a degenerate zero-energy mode which cannot be lifted by strong magnetic fields. |
Peres, N M R; dos Santos, Lopes J M B; Neto, Castro A H Coulomb drag and high-resistivity behavior in double-layer graphene Journal Article EPL, 95 (1), 2011, ISSN: 0295-5075. @article{ISI:000291990600030, title = {Coulomb drag and high-resistivity behavior in double-layer graphene}, author = {N M R Peres and Lopes J M B dos Santos and Castro A H Neto}, doi = {10.1209/0295-5075/95/18001}, times_cited = {0}, issn = {0295-5075}, year = {2011}, date = {2011-07-01}, journal = {EPL}, volume = {95}, number = {1}, publisher = {IOP PUBLISHING LTD}, address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, abstract = {We show that Coulomb drag in ultra-clean graphene double layers can be used for controlling the on-and-off ratio for current flow by tuning the external gate voltage. Hence, although graphene remains semi-metallic, the double-layer graphene system can be tuned from conductive to a highly resistive state. We show that our results explain previous data of Coulomb drag in double-layer graphene samples in disordered SiO2 substrates. Copyright (C) EPLA, 2011}, keywords = {}, pubstate = {published}, tppubtype = {article} } We show that Coulomb drag in ultra-clean graphene double layers can be used for controlling the on-and-off ratio for current flow by tuning the external gate voltage. Hence, although graphene remains semi-metallic, the double-layer graphene system can be tuned from conductive to a highly resistive state. We show that our results explain previous data of Coulomb drag in double-layer graphene samples in disordered SiO2 substrates. Copyright (C) EPLA, 2011 |
Avsar, Ahmet; Yang, Tsung-Yeh; Bae, Sukang; Balakrishnan, Jayakumar; Volmer, Frank; Jaiswal, Manu; Yi, Zheng; Ali, Syed Rizwan; Guentherodt, Gernot; Hong, Byung Hee; Beschoten, Bernd; Oezyilmaz, Barbaros Toward Wafer Scale Fabrication of Graphene Based Spin Valve Devices Journal Article NANO LETTERS, 11 (6), pp. 2363-2368, 2011, ISSN: 1530-6984. @article{ISI:000291322600029, title = {Toward Wafer Scale Fabrication of Graphene Based Spin Valve Devices}, author = {Ahmet Avsar and Tsung-Yeh Yang and Sukang Bae and Jayakumar Balakrishnan and Frank Volmer and Manu Jaiswal and Zheng Yi and Syed Rizwan Ali and Gernot Guentherodt and Byung Hee Hong and Bernd Beschoten and Barbaros Oezyilmaz}, doi = {10.1021/nl200714q}, times_cited = {2}, issn = {1530-6984}, year = {2011}, date = {2011-06-01}, journal = {NANO LETTERS}, volume = {11}, number = {6}, pages = {2363-2368}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {We demonstrate injection, transport, and detection of spins in spin valve arrays patterned in both copper based chemical vapor deposition (Cu-CVD) synthesized wafer scale single layer and bilayer graphene. We observe spin relaxation times comparable to those reported for exfoliated graphene samples demonstrating that chemical vapor deposition specific structural differences such as nanoripples do not limit spin transport in the present samples. Our observations make Cu-CVD graphene a promising material of choice for large scale spintronic applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We demonstrate injection, transport, and detection of spins in spin valve arrays patterned in both copper based chemical vapor deposition (Cu-CVD) synthesized wafer scale single layer and bilayer graphene. We observe spin relaxation times comparable to those reported for exfoliated graphene samples demonstrating that chemical vapor deposition specific structural differences such as nanoripples do not limit spin transport in the present samples. Our observations make Cu-CVD graphene a promising material of choice for large scale spintronic applications. |
Nayak, Tapas R; Andersen, Henrik; Makam, Venkata S; Khaw, Clement; Bae, Sukang; Xu, Xiangfan; Ee, Pui-Lai R; Ahn, Jong-Hyun; Hong, Byung Hee; Pastorin, Giorgia; Oezyilmaz, Barbaros Graphene for Controlled and Accelerated Osteogenic Differentiation of Human Mesenchymal Stem Cells Journal Article ACS NANO, 5 (6), pp. 4670-4678, 2011, ISSN: 1936-0851. @article{ISI:000292055200049, title = {Graphene for Controlled and Accelerated Osteogenic Differentiation of Human Mesenchymal Stem Cells}, author = {Tapas R Nayak and Henrik Andersen and Venkata S Makam and Clement Khaw and Sukang Bae and Xiangfan Xu and Pui-Lai R Ee and Jong-Hyun Ahn and Byung Hee Hong and Giorgia Pastorin and Barbaros Oezyilmaz}, doi = {10.1021/nn200500h}, times_cited = {0}, issn = {1936-0851}, year = {2011}, date = {2011-06-01}, journal = {ACS NANO}, volume = {5}, number = {6}, pages = {4670-4678}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Current tissue engineering approaches combine different scaffold materials with living cells to provide biological substitutes that can repair and eventually improve tissue functions. Both natural and synthetic materials have been fabricated for transplantation of stem cells and their specific differentiation Into muscles, bones, and cartilages. One of the key objectives for bone regeneration therapy to be successful Is to direct stem cells' proliferation and to accelerate their differentiation in a controlled manner through the use of growth factors and osteogenic inducers. Here we show that graphene provides a promising biocompatible scaffold that does not hamper the proliferation of human mesenchymal stem cells (hMSCs) and accelerates their specific differentiation into bone cells. The differentiation rate Is comparable to the one achieved with common growth factors, demonstrating graphene's potential for stem cell research.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Current tissue engineering approaches combine different scaffold materials with living cells to provide biological substitutes that can repair and eventually improve tissue functions. Both natural and synthetic materials have been fabricated for transplantation of stem cells and their specific differentiation Into muscles, bones, and cartilages. One of the key objectives for bone regeneration therapy to be successful Is to direct stem cells' proliferation and to accelerate their differentiation in a controlled manner through the use of growth factors and osteogenic inducers. Here we show that graphene provides a promising biocompatible scaffold that does not hamper the proliferation of human mesenchymal stem cells (hMSCs) and accelerates their specific differentiation into bone cells. The differentiation rate Is comparable to the one achieved with common growth factors, demonstrating graphene's potential for stem cell research. |
Neto, Antonio Castro H Another Spin on Graphene Journal Article SCIENCE, 332 (6027), pp. 315-316, 2011, ISSN: 0036-8075. @article{ISI:000289516600033, title = {Another Spin on Graphene}, author = {Antonio Castro H Neto}, doi = {10.1126/science.1204496}, times_cited = {0}, issn = {0036-8075}, year = {2011}, date = {2011-04-15}, journal = {SCIENCE}, volume = {332}, number = {6027}, pages = {315-316}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, address = {1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Neto, Castro A H; Novoselov, K Two-Dimensional Crystals: Beyond Graphene Journal Article MATERIALS EXPRESS, 1 (1), pp. 10-17, 2011, ISSN: 2158-5849. @article{ISI:000311866900002, title = {Two-Dimensional Crystals: Beyond Graphene}, author = {Castro A H Neto and K Novoselov}, doi = {10.1166/mex.2011.1002}, times_cited = {0}, issn = {2158-5849}, year = {2011}, date = {2011-03-01}, journal = {MATERIALS EXPRESS}, volume = {1}, number = {1}, pages = {10-17}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {Human progress and development has always been marked by breakthroughs in the control of materials. Since pre-historic times, through the stone, bronze, and iron ages, humans have exploited their environment for materials that can be either used directly or can be modified for their benefit, to make their life more comfortable, productive, or to give them military advantage. One age replaces another when the material that is the basis for its sustainability runs its course and is replaced by another material which presents more qualities. Multi-tasking, speed, versatility, and flexibility are at the heart of modern technology. In recent years a new class of materials that can fulfill these needs have emerged: two-dimensional (2D) crystals. Graphene is probably the most famous example, but there are numerous other examples with amazing electronic and structural properties. In this paper we look into the possible routes for exploration of this new field that presents new venues in basic science as well as in applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Human progress and development has always been marked by breakthroughs in the control of materials. Since pre-historic times, through the stone, bronze, and iron ages, humans have exploited their environment for materials that can be either used directly or can be modified for their benefit, to make their life more comfortable, productive, or to give them military advantage. One age replaces another when the material that is the basis for its sustainability runs its course and is replaced by another material which presents more qualities. Multi-tasking, speed, versatility, and flexibility are at the heart of modern technology. In recent years a new class of materials that can fulfill these needs have emerged: two-dimensional (2D) crystals. Graphene is probably the most famous example, but there are numerous other examples with amazing electronic and structural properties. In this paper we look into the possible routes for exploration of this new field that presents new venues in basic science as well as in applications. |
2010 |
Pereira, Vitor M; Ribeiro, R M; Peres, N M R; Neto, Castro A H Optical properties of strained graphene Journal Article EPL, 92 (6), 2010, ISSN: 0295-5075. @article{ISI:000287023900021, title = {Optical properties of strained graphene}, author = {Vitor M Pereira and R M Ribeiro and N M R Peres and Castro A H Neto}, doi = {10.1209/0295-5075/92/67001}, times_cited = {0}, issn = {0295-5075}, year = {2010}, date = {2010-12-01}, journal = {EPL}, volume = {92}, number = {6}, publisher = {IOP PUBLISHING LTD}, address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, abstract = {The optical conductivity of graphene strained uniaxially is studied within the Kubo-Greenwood formalism. Focusing on inter-band absorption, we analyze and quantify the breakdown of universal transparency in the visible region of the spectrum, and analytically characterize the transparency as a function of strain and polarization. Measuring transmittance as a function of incident polarization directly reflects the magnitude and direction of strain. Moreover, direction-dependent selection rules permit the identification of the lattice orientation by monitoring the van Hove transitions. These photoelastic effects in graphene can be explored towards atomically thin, broadband optical elements. Copyright (C) EPLA, 2010}, keywords = {}, pubstate = {published}, tppubtype = {article} } The optical conductivity of graphene strained uniaxially is studied within the Kubo-Greenwood formalism. Focusing on inter-band absorption, we analyze and quantify the breakdown of universal transparency in the visible region of the spectrum, and analytically characterize the transparency as a function of strain and polarization. Measuring transmittance as a function of incident polarization directly reflects the magnitude and direction of strain. Moreover, direction-dependent selection rules permit the identification of the lattice orientation by monitoring the van Hove transitions. These photoelastic effects in graphene can be explored towards atomically thin, broadband optical elements. Copyright (C) EPLA, 2010 |