Small

Cover image for Vol. 6 Issue 11

June 6, 2010

Volume 6, Issue 11

Pages 1163–1254

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Contents
    5. Communications
    6. Full Papers
    1. Graphene: Patterned Growth of Graphene over Epitaxial Catalyst Small 11/2010

      Hiroki Ago, Izumi Tanaka, Carlo M. Orofeo, Masaharu Tsuji and Ken-ichi Ikeda

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/smll.201090034

      Thumbnail image of graphical abstract

      The cover picture illustrates the formation of a triangular graphene film inside a pit of epitaxial metal catalyst. Rectangular- and triangular-shaped microscale graphene films are grown on epitaxial Co films deposited on single-crystal MgO substrates with (001) and (111) planes, respectively. Thermal decomposition of polystyrene over the epitaxial metal film in high vacuum gives unique pits, whose orientation and shape are strongly dependent on the crystallographic orientation of the MgO substrate. Raman-mapping measurements reveal preferential formation of few-layer-graphene films inside these pits. These graphene films are transferred onto a SiO2/Si substrate while maintaining the original shape, and field-effect transistors are fabricated using the transferred films. These findings offer lithography-free patterned growth of graphene for future electronics. For more information, please read the Full Paper “Patterned Growth of Graphene over Epitaxial Catalyst” by H. Ago et al., beginning on page 1226.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Contents
    5. Communications
    6. Full Papers
    1. Nanobiosensors: Constraint of DNA on Functionalized Graphene Improves its Biostability and Specificity Small 11/2010

      Zhiwen Tang, Hong Wu, John R. Cort, Garry W. Buchko, Youyu Zhang, Yuyan Shao, Ilhan A. Aksay, Jun Liu and Yuehe Lin

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/smll.201090035

      Thumbnail image of graphical abstract

      The cover picture shows how single-stranded DNA can be effectively and promptly adsorbed onto functionalized graphene via hydrophobic and π-stacking interactions. Interestingly, the absorbed single-stranded DNA can be effectively protected from enzymatic cleavage, which is encouraging for potential graphene-based biomedical applications involving complex cellular and biofluids samples. Anisotropy, fluorescence, NMR, and CD studies suggest that single-stranded DNA adsorbed onto functionalized graphene forms strong molecular interactions that prevent DNase I from approaching the constrained DNA. Furthermore, constraining a single-stranded DNA probe on graphene improves the specificity of its response to a target sequence. The unique features of DNA–graphene interactions are promising traits that may be exploited to construct DNA–graphene nanobiosensors with facile design, excellent sensitivity, selectivity, and biostability. For more information, please read the Communication “Constraint of DNA on Functionalized Graphene Improves its Biostability and Specificity” by Y. Lin et al., beginning on page 1205.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Contents
    5. Communications
    6. Full Papers
    1. Contents: Small 11/2010 (pages 1163–1167)

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/smll.201090036

  4. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Contents
    5. Communications
    6. Full Papers
    1. Metal sensing

      Periodic Mesoporous Organosilica Films: Key Components of Fiber-Optic-Based Heavy-Metal Sensors (pages 1168–1172)

      Jenny Du, Judy Cipot-Wechsler, Jose M. Lobez, Hans-Peter Loock and Cathleen M. Crudden

      Version of Record online: 11 MAY 2010 | DOI: 10.1002/smll.201000269

      Thumbnail image of graphical abstract

      Thick, tetrasulfide-functionalized periodic mesoporous organosilica films are presented as chemically specific coatings on long-period grating (LPG)-inscribed fiber-optic waveguides for the direct, parts per billion (ppb)-level detection of Pb(II) species in solution.

    2. Nanomaterials

      Hydrothermal Synthesis of Bi6S2O15 Nanowires: Structural, in situ EXAFS, and Humidity-Sensing Studies (pages 1173–1179)

      Ying Zhou, Jan-Dierk Grunwaldt, Frank Krumeich, Kaibo Zheng, Guorong Chen, Jan Stötzel, Ronald Frahm and Greta R. Patzke

      Version of Record online: 19 MAY 2010 | DOI: 10.1002/smll.201000112

      Thumbnail image of graphical abstract

      Sensing oxysulfates: A new type of bismuth oxysulfate nanowire emerges from the straightforward hydrothermal reaction of Bi2O3 and K2SO4. The formation pathway of this versatile material is monitored with in situ QEXAFS techniques. The high-aspect-ratio nanorods display promising features for application in humidity sensors.

    3. Nanotubes

      TiO2 Nano Test Tubes as a Self-Cleaning Platform for High-Sensitivity Immunoassays (pages 1180–1184)

      Yan-Yan Song, Felix Schmidt-Stein, Steffen Berger and Patrik Schmuki

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/smll.200902116

      Thumbnail image of graphical abstract

      High-aspect-ratio TiO2 nanotube (TiNT) layers can be used as low-cost, low-volume arrays for fluorescence immunosensing. High sensitivity for antibodies at a concentration of 0.01 pg mL−1 is provided by the high observation length (L) of the nanotubes. The photocatalytic properties of TiO2 make the TiNT arrays reusable after a short UV treatment.

    4. Mesoporous silica nanoparticles

      Mesoporous Silica Nanoparticles Facilitate Delivery of siRNA to Shutdown Signaling Pathways in Mammalian Cells (pages 1185–1190)

      Christopher Hom, Jie Lu, Monty Liong, Hanzhi Luo, Zongxi Li, Jeffrey I. Zink and Fuyuhiko Tamanoi

      Version of Record online: 11 MAY 2010 | DOI: 10.1002/smll.200901966

      Thumbnail image of graphical abstract

      A nanocomplex assembly of polyethylenimine and mesoporous silica nanoparticles are used to successfully protect and deliver siRNA into human cells, effectively shutting down both exogenous and endogenous gene signal.

    5. Self-assembly

      Synthetic Viruslike Particles and Hybrid Constructs Based on Lipopeptide Self-Assembly (pages 1191–1196)

      Adam W. Perriman, David S. Williams, Andrew J. Jackson, Isabelle Grillo, Jimy M. Koomullil, Arin Ghasparian, John A. Robinson and Stephen Mann

      Version of Record online: 11 MAY 2010 | DOI: 10.1002/smll.200901186

      Thumbnail image of graphical abstract

      A method for fabricating hybrid monodisperse nanostructures comprising synthetic viruslike particles enclosed in an impermeable ultrathin amorphous calcium phosphate shell is described. The native and hybrid nanostructures are fully characterized at nanometer resolution and the permeability of the coronal layer is probed using fluorescence spectroscopy.

    6. Nanowire switches

      Nanowire Mechanical Switch with a Built-In Diode (pages 1197–1200)

      Jin-Woo Han, Jae-Hyuk Ahn, Min-Wu Kim, Jeong Oen Lee, Jun-Bo Yoon and Yang-Kyu Choi

      Version of Record online: 11 MAY 2010 | DOI: 10.1002/smll.201000170

      Thumbnail image of graphical abstract

      A nanoelectromechanical switch consists of two landing electrodes on either side of a movable silicon nanowire, separated by a nanoscale air gap. The bistable mechanical state of the nanowire determines an on/off state, which is sensed by measuring the contact resistance. The n-type semiconductor electrodes and p-type nanowire form a p–n junction diode at the cross-point.

    7. Encapsulation

      Magnetite-Nanoparticle-Encapsulated pH-Responsive Polymeric Micelle as an MRI Probe for Detecting Acidic Pathologic Areas (pages 1201–1204)

      Guang Hui Gao, Geun Ho Im, Min Sang Kim, Jae Won Lee, Jehoon Yang, Hyesung Jeon, Jung Hee Lee and Doo Sung Lee

      Version of Record online: 6 MAY 2010 | DOI: 10.1002/smll.200902317

      Thumbnail image of graphical abstract

      A facile and powerful pH-responsive polymeric micelle encapsulates Fe3O4 nanoparticles as an acid-targeting MRI contrast agent for pathologic diagnosis. This MRI probe remains in a micellar state in the physiological environment whereas it can be dissolved in acidic pathological areas. More biomedical applications will be possible owing to its unique ability to target an acidic pathologic environment.

    8. Nanobiosensors

      Constraint of DNA on Functionalized Graphene Improves its Biostability and Specificity (pages 1205–1209)

      Zhiwen Tang, Hong Wu, John R. Cort, Garry W. Buchko, Youyu Zhang, Yuyan Shao, Ilhan A. Aksay, Jun Liu and Yuehe Lin

      Version of Record online: 11 MAY 2010 | DOI: 10.1002/smll.201000024

      Thumbnail image of graphical abstract

      Single-stranded DNA constrained on a graphene surface is effectively protected from enzymatic cleavage by DNase I. Various spectroscopy studies suggest that the single-stranded DNA is promptly adsorbed onto graphene forming strong molecular interactions. Constraint of the DNA probe on the graphene surface improves the specificity of its response to complementary DNA.

    9. Field-effect transistors

      Channel-Length-Dependent Field-Effect Mobility and Carrier Concentration of Reduced Graphene Oxide Thin-Film Transistors (pages 1210–1215)

      Toshiyuki Kobayashi, Nozomi Kimura, Junbin Chi, Shintaro Hirata and Daisuke Hobara

      Version of Record online: 6 MAY 2010 | DOI: 10.1002/smll.200902407

      Thumbnail image of graphical abstract

      Reduced graphene oxide thin-film transistors exhibit unique channel-length-dependent field-effect mobilities and carrier concentrations due to their structural and electronic properties. Increase in these characteristics with decreasing channel length is a consequence of the hopping transport from nanosheet to nanosheet and pinning of the Fermi energy at source and drain electrodes.

    10. Gold clusters

      HCl-Induced Nuclearity Convergence in Diphosphine-Protected Ultrasmall Gold Clusters: A Novel Synthetic Route to “Magic-Number” Au13 Clusters (pages 1216–1220)

      Yukatsu Shichibu and Katsuaki Konishi

      Version of Record online: 18 MAY 2010 | DOI: 10.1002/smll.200902398

      Thumbnail image of graphical abstract

      A magic-number Au13 cluster with icosahedral geometry can be exclusively generated from a polydisperse mixture of ultrasmall 1,2-bis(diphenylphosphino)ethane-coordinated gold clusters upon treatment with HCl, which acts as an efficient promoter.

    11. Nanoreactors

      Polymerase-Functionalized Hierarchical Mesoporous Titania Thin Films: Towards a Nanoreactor Platform for DNA Amplification (pages 1221–1225)

      Martín G. Bellino, Ivanna Tropper, Hebe Duran, Alberto E. Regazzoni and Galo J. A. A. Soler-Illia

      Version of Record online: 11 MAY 2010 | DOI: 10.1002/smll.201000066

      Thumbnail image of graphical abstract

      Titania thin films with hierarchical nanopore architecture are efficient hosts for Taq polymerase, which is selectively located in large-size mesopores. These biofunctional nanomaterials, highly tuned on the biomolecular length scale, are able to efficiently amplify DNA in a polymerase chain reaction. The engineered pore sizes and interconnectivity at the nanoscale are the key to bio-functionalization and enzyme performance.

  5. Full Papers

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Contents
    5. Communications
    6. Full Papers
    1. Graphene

      Patterned Growth of Graphene over Epitaxial Catalyst (pages 1226–1233)

      Hiroki Ago, Izumi Tanaka, Carlo M. Orofeo, Masaharu Tsuji and Ken-ichi Ikeda

      Version of Record online: 19 MAY 2010 | DOI: 10.1002/smll.200902405

      Thumbnail image of graphical abstract

      Growth of graphene films over epitaxial metal films deposited on single-crystalline substrates is studied. The epitaxial metal film gives unique micropits with rectangular and triangular shapes, reflecting the crystallographic orientation of the substrate. Thin films of graphene are observed inside these pits. This patterned graphene is transformed on SiO2/Si substrates and their Raman spectra and atomic force microscopy data show the formation of few-layer graphene.

    2. Cancer therapy

      Cancer-Cell-Specific Induction of Apoptosis Using Mesoporous Silica Nanoparticles as Drug-Delivery Vectors (pages 1234–1241)

      Jessica M. Rosenholm, Emilia Peuhu, Laurel Tabe Bate-Eya, John E. Eriksson, Cecilia Sahlgren and Mika Lindén

      Version of Record online: 19 MAY 2010 | DOI: 10.1002/smll.200902355

      Thumbnail image of graphical abstract

      Nanocarrier-bound anticancer agent methotrexate (MTX) can function as both a drug and targeting ligand, as it is structurally similar to folic acid (FA) and hence binds to the same biological targets. A designed mesoporous drug-delivery vector combines enhanced apoptotic efficiency with selectivity between cancerous and non-cancerous cell lines, which leads to efficient targeted killing of cancer cells.

    3. Nanopatterning

      Fabrication of a 60-nm-Diameter Perfectly Round Metal-Dot Array over a Large Area on a Plastic Substrate Using Nanoimprint Lithography and Self-Perfection by Liquefaction (pages 1242–1247)

      Chao Wang, Qiangfei Xia, Wen-Di Li, Zengli Fu, Keith J. Morton and Stephen Y. Chou

      Version of Record online: 6 MAY 2010 | DOI: 10.1002/smll.201000104

      Thumbnail image of graphical abstract

      A new method is proposed for nanopatterning on plastic substrates based on the use of a thin hydrogen silsesquioxane layer on top of polyethylene terephthalate (PET), nanoimprint lithography, and self-perfection by liquefaction. Use of the method achieves arrays of 60-nm-diameter, perfectly round metal dots over a large area on a PET substrate with high fidelity and high yield.

    4. Electrohydrodynamic lithography

      Rapid Electrohydrodynamic Lithography Using Low-Viscosity Polymers (pages 1248–1254)

      Pola Goldberg-Oppenheimer and Ullrich Steiner

      Version of Record online: 19 MAY 2010 | DOI: 10.1002/smll.201000060

      Thumbnail image of graphical abstract

      Films of polymers with low glass-transition temperatures are destabilized by electric fields of 10–80 V µm−1. The low melt viscosities of the polymers allow the replication of electrode patterns with micrometer-sized features in less than 10 s. Pattern formation is monitored in real time by recording the current passing through the capacitor device, and is correlated to the different stages of electrohydrodynamic patterning.

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