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Cover image for Vol. 3 Issue 4

April 2, 2007

Volume 3, Issue 4

Pages 521–703

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
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    1. Cover Picture: Optimal Atomistic Modifications of Material Surfaces: Design of Selective Nesting Sites for Biomolecules (Small 4/2007) (page 521)

      Boyang Wang and Petr Král

      Article first published online: 22 MAR 2007 | DOI: 10.1002/smll.200790008

      The cover picture illustrates the electrostatic potential of the Ala-Tyr-Met peptide that is Coulombically docked in a highly selective nest formed on a B- and N-doped graphene layer. The optimally designed nesting site has an electrostatic potential distribution that is largely complementary to that of the peptide. This methodology can selectively bind solvated proteins on material surfaces modified by covalently attached charged ligands, and it has numerous potential applications in the formation of hybrid biofunctional systems at the nanoscale. For more information, please read the Communication “Optimal Atomistic Modifications of Material Surfaces: Design of Selective Nesting Sites for Biomolecules” by Boyang Wang and Petr Král beginning on page 580.

  2. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
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    1. Graphical Abstract: Small 4/2007 (pages 523–529)

      Article first published online: 22 MAR 2007 | DOI: 10.1002/smll.200790009

  3. News

    1. Top of page
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    3. Graphical Abstract
    4. News
    5. Review
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    1. News from the micro–nano world: Small 4/2007 (pages 532–533)

      M. E. Franke

      Article first published online: 22 MAR 2007 | DOI: 10.1002/smll.200700170

    2. From our sister journals: Small 4/2007 (pages 534–535)

      Article first published online: 22 MAR 2007 | DOI: 10.1002/smll.200790010

  4. Review

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
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    1. Infrared-Emitting Colloidal Nanocrystals: Synthesis, Assembly, Spectroscopy, and Applications (pages 536–557)

      Andrey L. Rogach, Alexander Eychmüller, Stephen G. Hickey and Stephen V. Kershaw

      Article first published online: 6 MAR 2007 | DOI: 10.1002/smll.200600625

      Thumbnail image of graphical abstract

      IR will go far: There is currently enormous interest in the preparation and application of nanocrystalline materials whose emission is centered in the infrared region of the spectrum. Advances in telecommunications, biological imaging, and LED technology are but some of the many possible fields envisaged to benefit from such tunable materials. This Review provides a comprehensive view of the recent efforts to prepare and utilize IR-emitting II–VI, III–V, and IV–VI nanocrystals.

  5. Communications

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
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    1. In Vitro and In Vivo Enzymatic Formation of Supramolecular Hydrogels Based on Self-Assembled Nanofibers of a β-Amino Acid Derivative (pages 558–562)

      Zhimou Yang, Gaolin Liang, Manlung Ma, Yuan Gao and Bing Xu

      Article first published online: 26 FEB 2007 | DOI: 10.1002/smll.200700015

      Thumbnail image of graphical abstract

      A precursor of a β-peptide derivative transforms into a hydrogelator and forms supramolecular hydrogels upon phosphatase-catalyzed dephosphorylation. This new strategy works in vitro and in vivo (see image). The enzymatic hydrogelation in vivo indicates that the β-peptide-based hydrogel exhibits a longer lifetime than that of α-peptide hydrogel in a subcutaneous environment. Such an excellent in vivo stability renders the β-peptide-based hydrogel as a potential candidate for biomedical applications.

    2. Realization of Atomically Controlled Dopant Devices in Silicon (pages 563–567)

      Frank J. Rueß, Wilson Pok, Thilo C. G. Reusch, Matthew J. Butcher, Kuan Eng J. Goh, Lars Oberbeck, Giordano Scappucci, Alex R. Hamilton and Michelle Y. Simmons

      Article first published online: 6 MAR 2007 | DOI: 10.1002/smll.200600680

      Thumbnail image of graphical abstract

      Molecular beam epitaxy and scanning tunneling microscopy (STM) patterning are combined to form highly doped, planar devices in silicon at the atomic level. The absolute device location is registered to microscopic markers (see image; scale bar: 50 μm) for the alignment of surface contacts, enabling the correlation of the electrical properties of atomically controlled devices such as nanowires, tunnel junctions, and nanodots to the dopant location, monitored using high-resolution STM techniques.

    3. ZnO-Nanowire-Inserted GaN/ZnO Heterojunction Light-Emitting Diodes (pages 568–572)

      Min-Chang Jeong, Byeong-Yun Oh, Moon-Ho Ham, Sang-Won Lee and Jae-Min Myoung

      Article first published online: 12 FEB 2007 | DOI: 10.1002/smll.200600479

      Thumbnail image of graphical abstract

      Out of the blue: Light-emitting diodes were obtained by fabricating p+-GaN film/n-ZnO nanowire array/n+-ZnO film structures (see figure). Blue electroluminescence (EL) emission was observed from the nanowire-inserted heterojunction diodes under forward bias. These diodes exhibited improved EL emission and injection current compared to those of film-based heterojunction diodes.

    4. Novel Dome-Shaped Structures for High-Efficiency Patterning of Individual Microbeads in a Microfluidic Device (pages 573–579)

      Chee Tiong Lim and Yong Zhang

      Article first published online: 12 MAR 2007 | DOI: 10.1002/smll.200600435

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      A soft-lithography technique is used to fabricate a microfluidic device with very unique dome-shaped structures (see image), which are essential for high-efficiency immobilization and patterning of single beads. Immobilization of the microbeads was achieved by physical entrapment of the beads and patterning was performed at a relatively high flow rate. With such features, encoded microbeads can be incorporated into microfluidic devices to carry out biological assays, significantly increasing their multiplexing capability.

      Corrected by:

      Corrigendum: Novel Dome-Shaped Structures for High-Efficiency Patterning of Individual Microbeads in a Microfluidic Device

      Vol. 3, Issue 5, 714, Article first published online: 26 APR 2007

    5. Optimal Atomistic Modifications of Material Surfaces: Design of Selective Nesting Sites for Biomolecules (pages 580–584)

      Boyang Wang and Petr Král

      Article first published online: 27 FEB 2007 | DOI: 10.1002/smll.200600433

      Thumbnail image of graphical abstract

      A methodology of optimal modification of material surfaces is developed to design selective nesting sites for inorganic, organic, and biological molecules. Surfaces are modified by atomic dopants and charged ligands in such a way that the created local electric fields form selective Coulombic traps for the adsorbed molecules. The methodology is demonstrated by molecular dynamics simulations of short peptides docked in nesting sites designed on graphene sheets substitutionally doped with B and N atoms. The image shows the electrostatic potential distribution of a docked peptide.

    6. Controlled Radial Distribution of Nanoscale Vesicles During Binding to an Oscillating QCM Surface (pages 585–589)

      Malin Edvardsson, Vladimir P. Zhdanov and Fredrik Höök

      Article first published online: 2 MAR 2007 | DOI: 10.1002/smll.200600458

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      Finding the right balance: By utilizing the Gaussian shaped oscillation–amplitude distribution across the surface of a sensor, it is demonstrated how the driving voltage of the crystal of a quartz crystal microbalance can be used to ensure binding of vesicles above a predefined radius to the peripheral regions of the crystal only, thus ensuring the presence of smaller sized vesicles in the central region of the crystal.

    7. Enzymatic Disassembly of DNA–Gold Nanostructures (pages 590–594)

      Antonios G. Kanaras, Zhenxin Wang, Mathias Brust, Richard Cosstick and Andrew D. Bates

      Article first published online: 22 FEB 2007 | DOI: 10.1002/smll.200600494

      Thumbnail image of graphical abstract

      The efficient digestion of nanoparticle assemblies connected by DNA linkers is demonstrated using a number of complementary methods (enzymatic cleavage with EcoRI is shown in the scheme). The efficiency of digestion is dependent on the design of the DNA linker. The ability to manipulate DNA enzymatically is important in the development of hierarchical chemical methods of nanoscale assembly.

    8. Compression-Modulated Tunable-Pore Carbon-Nanotube Membrane Filters (pages 595–599)

      Xuesong Li, Guangyu Zhu, Jonathan S. Dordick and Pulickel M. Ajayan

      Article first published online: 2 MAR 2007 | DOI: 10.1002/smll.200600652

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      Turn on the pressure: Vertically aligned carbon-nanotube membranes show super-compressive and elastic properties. The pore size can be dynamically and reversibly controlled by mechanical deformation of the membrane, over ranges useful for ultrafiltration (see picture). The separation of proteins with molecular weights of 14–540 kDa (about 5–20 nm in size) is demonstrated with a single membrane set at different pore sizes by mechanical stress.

    9. A “Molecular Eraser” for Dip-Pen Nanolithography (pages 600–605)

      Jae-Won Jang, Daniel Maspoch, Tsuyohiko Fujigaya and Chad A. Mirkin

      Article first published online: 27 FEB 2007 | DOI: 10.1002/smll.200600679

      Thumbnail image of graphical abstract

      The DPN eraser: Dip-pen-nanolithography- (DPN-) generated nanostructures can be repaired using a conductive atomic force microscope (AFM) and an adsorbate-coated AFM tip. This molecule-based erasing technique was used to transform a pattern of MHA in the form of the letters “DRN” into “DPN” (see figure). The technique facilitates removal and subsequent backfilling with a second molecule type.

    10. Facile Synthesis of Monodisperse Mn3O4 Tetragonal Nanoparticles and Their Large-Scale Assembly into Highly Regular Walls by a Simple Solution Route (pages 606–610)

      Ning Wang, Lin Guo, Lin He, Xia Cao, Chinping Chen, Rongming Wang and Shihe Yang

      Article first published online: 27 FEB 2007 | DOI: 10.1002/smll.200600283

      Thumbnail image of graphical abstract

      Walls that build themselves: Long-range nanowalls assemble with uniform tetragonal Mn3O4 nanoparticles by a simple solution-phase synthesis method under low temperature and surfactant-free conditions (see image). The magnetization of the sample is investigated. A mechanism for formation of the wall-like crystals is suggested. These high-quality single-crystalline Mn3O4 nanopatterns hold great potential for fundamental studies of their properties as well as for applications in nanodevices.

    11. Nanoscale Phase-Aggregation-Induced Performance Improvement of Polymer Solar Cells (pages 611–615)

      Xiaoniu Yang, Guanghao Lu, Ligui Li and Enle Zhou

      Article first published online: 6 MAR 2007 | DOI: 10.1002/smll.200600571

      Thumbnail image of graphical abstract

      Solar system: The performance of poly(3-hexylthiophene)/C60 polymer solar cells is improved after thermal post-treatment due to the optimization of the morphology of the photoactive layer, which creates efficient pathways for electron transportation to the cathode through nanoscale C60 crystals and their distribution in the layer. The photoactive layer evolves from a homogeneous composite film to one with nanoscale C60 crystals within the film (see picture).

    12. Transfer Printing of Submicrometer Patterns of Aligned Carbon Nanotubes onto Functionalized Electrodes (pages 616–621)

      Sai Li, Yehai Yan, Ningyi Liu, Mary B. Chan-Park and Qing Zhang

      Article first published online: 12 FEB 2007 | DOI: 10.1002/smll.200600525

      Thumbnail image of graphical abstract

      Fluidic aligned submicrometer patterns of acid-treated carbon nanotubes (CNTs) on polydimethysiloxane (PDMS) were transfer printed onto nonflat patterned Au electrodes modified with a self-assembled monolayer (SAM) of 11-amino-1-undecanethiol. The CNT bundles can be transferred in a few seconds at ambient temperature onto the electrodes. The horizontally aligned CNT bundles can be placed in any orientation with respect to the Au electrodes (see figure), and CNT field-effect transistors can be fabricated.

    13. Vertically Aligned Zn2SiO4 Nanotube/ZnO Nanowire Heterojunction Arrays (pages 622–626)

      Jun Zhou, Jin Liu, Xudong Wang, Jinhui Song, Rao Tummala, Ning Sheng Xu and Zhong Lin Wang

      Article first published online: 19 FEB 2007 | DOI: 10.1002/smll.200600495

      Thumbnail image of graphical abstract

      Up the junction: An approach for fabricating Zn2SiO4 nanotube/ZnO nanowire heterojunction arrays (see picture) is introduced by using ZnO-nanowire arrays as a template. The technique, which is based on a plasma-enhanced chemical vapor deposition process, reveals a novel, low-cost, and efficient method for aligning nanotube/nanowire heterojunctions, which could be useful for fabricating novel nanodevices.

  6. Full Papers

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
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    1. Controlled Assembly of Spherical Nanoparticles: Nanowires and Spherulites (pages 628–635)

      Alberto Striolo

      Article first published online: 27 FEB 2007 | DOI: 10.1002/smll.200600661

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      According to the presented simulations, it is possible to tune the shape of self-assembled supramolecular aggregates of nanoparticles by attaching short polymer brushes on the equatorial plane of the nanoparticles (see figure). This affects the attractive/repulsive properties of the particles, which can be fine-tuned by using suitable solvent conditions. In this way nanowires or spherulites can be obtained.

    2. Tunable Film Degradation and Sustained Release of Plasmid DNA from Cleavable Polycation/Plasmid DNA Multilayers under Reductive Conditions (pages 636–643)

      Jun Chen, Shi-Wen Huang, Wen-Hai Lin and Ren-Xi Zhuo

      Article first published online: 12 MAR 2007 | DOI: 10.1002/smll.200600301

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      DNA by degradation: Multilayer polymer/DNA assemblies have been prepared on quartz and silicon substrates (an AFM image of one such film is shown; scale in μm), which have the capacity to release the incorporated DNA through degradation on immersion in a buffer solution containing dithiothreitol. The degree of degradation and DNA release can be controlled by adjusting the concentration of the reducing agent. Such materials offer great promise for various biomedical applications.

    3. Preparation of Ferrocene Nanocrystals by the Ultrasonic-Solvent-Substitution Method and Their Electrochemical Properties (pages 644–649)

      Ping Chen, Qing-Sheng Wu and Ya-Ping Ding

      Article first published online: 2 MAR 2007 | DOI: 10.1002/smll.200600374

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      Ferrocene nanocrystals (see image) are prepared via an ultrasonic-solvent-substitution method. Ferrocene-nanosphere-modified GC electrodes exhibit a better electrocatalytic property than those modified towards ascorbic acid by the ferrocene bulk material in phosphate buffer. This effect will be of great importance in the fields of electrocatalysis, water treatment, medicine, and so on.

    4. Temperature-, pH-, and Magnetic-Field-Sensitive Hybrid Microgels (pages 650–657)

      Sanchita Bhattacharya, Franziska Eckert, Volodymyr Boyko and Andrij Pich

      Article first published online: 6 MAR 2007 | DOI: 10.1002/smll.200600590

      Thumbnail image of graphical abstract

      Multiple sensitivity: Polymeric microgels with temperature and pH sensitivity can be modified by magnetite nanoparticles. Microgel particles containing 8.41 wt % Fe3O4 (see TEM image) demonstrate that the nanoparticles are located in the thermosensitive microgel shell. The microgels have high magnetization values and are able to change their dimensions reversibly in response to temperature and pH.

    5. Nitrogen-Doped Tungsten Oxide Nanowires: Low-Temperature Synthesis on Si, and Electrical, Optical, and Field-Emission Properties (pages 658–664)

      Mu-Tung Chang, Li-Jen Chou, Yu-Lun Chueh, Yu-Chen Lee, Chin-Hua Hsieh, Chii-Dong Chen, Yann-Wen Lan and Lih-Juann Chen

      Article first published online: 22 FEB 2007 | DOI: 10.1002/smll.200600562

      Thumbnail image of graphical abstract

      Nanowire growth: Nitrogen-doped WO3 nanowires are grown on a 4-inch Si(100) wafer at low temperature by a vapor–solid mechanism (see picture). The nanowires have lengths and diameters up to 5 μm and 25–35 nm, respectively. The approach can be used to produce WO3 nanowires on Si in large quantities. The optical, field-emission, and electrical properties indicate that the nanowires could have extensive applications in nanodevices.

    6. Interfacial Assembly of Partially Hydrophobic Silica Nanoparticles Induced by Ultrasonic Treatment (pages 665–671)

      Dmitry Grigoriev, Reinhard Miller, Dmitry Shchukin and Helmuth Möhwald

      Article first published online: 6 MAR 2007 | DOI: 10.1002/smll.200600613

      Thumbnail image of graphical abstract

      Sounds good: Sonochemistry can be applied to prepare aqueous suspensions of air-filled nanostructured silica microshells from surface-engineered nanoparticles. Specific conditions at the cavitation interface result in partial crystallization of the amorphous silica nanoparticles producing the quartz phase of the silica particles and a high degree of interconnection between the silica nanoparticles in the microsphere shells (see image).

    7. Identification of Active Biomolecules in the High-Yield Synthesis of Single-Crystalline Gold Nanoplates in Algal Solutions (pages 672–682)

      Jianping Xie, Jim Yang Lee, Daniel I. C. Wang and Yen Peng Ting

      Article first published online: 14 FEB 2007 | DOI: 10.1002/smll.200600612

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      A protein to make plates: The active biomolecules in the algal synthesis of gold nanoplates have been identified. A protein with a molecular weight of approximately 28 kDa was isolated and purified and it was found to possess both reduction and shape-directing functionalities. The protein could be used to produce plates with lateral sizes ranging from nanometers to micrometers (see image).

    8. Immunoisolating Pancreatic Islets by Encapsulation with Selective Withdrawal (pages 683–690)

      Jason L. Wyman, Seda Kizilel, Ryan Skarbek, Xiangyang Zhao, Matthew Connors, William S. Dillmore, William L. Murphy, Milan Mrksich, Sidney R. Nagel and Marc R. Garfinkel

      Article first published online: 6 MAR 2007 | DOI: 10.1002/smll.200600231

      Thumbnail image of graphical abstract

      Isolation for transplantation: Transplantation of microencapsulated pancreatic islets has long been pursued as a therapy for Type I diabetes. Presented here is the application of a novel coating technique, capable of generating poly(ethylene glycol) coats of approximately 10 μm that protect the enclosed islets (see image) from large antibody-sized molecules without inhibiting the diffusion of smaller insulin and glucose molecules.

      Corrected by:

      Retraction: Retraction: Immunoisolating Pancreatic Islets by Encapsulation with Selective Withdrawal

      Vol. 6, Issue 24, 2780, Article first published online: 14 DEC 2010

    9. Water-Soluble Germanium(0) Nanocrystals: Cell Recognition and Near-Infrared Photothermal Conversion Properties (pages 691–699)

      Timothy N. Lambert, Nicholas L. Andrews, Henry Gerung, Timothy J. Boyle, Janet M. Oliver, Bridget S. Wilson and Sang M. Han

      Article first published online: 14 FEB 2007 | DOI: 10.1002/smll.200600529

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      A signal achievement: Stable, water-soluble, crystalline Ge(0) nanocrystals (NCs) were prepared and shown to be capable of inducing cell signaling in RBL-2H3 mast cells with minimal toxicity. Both organic- and water-soluble Ge(0) NCs exhibited photothermal behavior when excited with near-infrared (NIR) radiation, even under repetitive and prolonged NIR laser exposure. The figure shows dye-labeled receptors on RBL-2H3 mast cells, crosslinked by derivatized Ge(0) NCs.

  7. Preview

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    6. Communications
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      Preview: Small 5/2007 (page 703)

      Article first published online: 22 MAR 2007 | DOI: 10.1002/smll.200790011

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