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Cover image for Vol. 9 Issue 3

February 11, 2013

Volume 9, Issue 3

Pages 333–486

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Review
    8. Communications
    9. Full Papers
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      Microfluidic Circuits: Self-Sorting of Deformable Particles in an Asynchronous Logic Microfluidic Circuit (Small 3/2013) (page 333)

      Marco A. Cartas-Ayala, Mohamed Raafat and Rohit Karnik

      Article first published online: 1 FEB 2013 | DOI: 10.1002/smll.201370015

      Thumbnail image of graphical abstract

      A microfluidic circuit described by R. Karnik and co-workers on page 375 can automatically sort deformable particles based on the hydrodynamic resistance they induce in a constrained microfluidic channel while flowing through it. The feedforward loop in the circuit is designed to dynamically modulate the flow rates at the bifurcating junction based on the hydrodynamic resistance that the particle induces just before arriving at the junction. A particle with hydrodynamic resistance above a certain threshold (green) is sorted, while a particle with hydrodynamic resistance below the threshold (orange) is rejected. The arrows indicate the magnitudes of flow rates in the channels.

  2. Inside Front Cover

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    5. Masthead
    6. Contents
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      3D Cell Cultures: Nanostructured Superhydrophobic Substrates Trigger the Development of 3D Neuronal Networks (Small 3/2013) (page 334)

      Tania Limongi, Fabrizia Cesca, Francesco Gentile, Roberto Marotta, Roberta Ruffilli, Andrea Barberis, Marco Dal Maschio, Enrica Maria Petrini, Stefania Santoriello, Fabio Benfenati and Enzo Di Fabrizio

      Article first published online: 1 FEB 2013 | DOI: 10.1002/smll.201370016

      Thumbnail image of graphical abstract

      On page 402, E. Di Fabrizio and co-workers describe the growth of neuron–astrocyte co-cultures on nanostructured superhydrophobic substrates. The scanning electron microscopy image on the inside cover shows a flat glial cell monolayer (pink) suspended between adjacent nanostructured pillars. Astrocytes adhere with high affinity to both the top and lateral surface of the pillars and provide an excellent support for cocultured neurons, as shown by a large neuron (blue) spreading upon the glial carpet with its multiple neuritic processes.

  3. Back Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Review
    8. Communications
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      Chemical Imaging: Chemical Imaging Beyond the Diffraction Limit: Experimental Validation of the PTIR Technique (Small 3/2013) (page 488)

      Basudev Lahiri, Glenn Holland and Andrea Centrone

      Article first published online: 1 FEB 2013 | DOI: 10.1002/smll.201370017

      Thumbnail image of graphical abstract

      Photothermal-induced resonance for chemical imaging at the nanoscale is described by A. Centrone and co-workers on page 439. An AFM cantilever measures instantaneous thermal expansion induced by light absorption in a sample. A pulsed laser, tunable across the mid-IR is used to illuminate the sample in a total internal reflection confi guration. If the laser wavelength matches the sample vibrational absorptions, the sample heats, expands, and deflects the cantilever faster than the AFM feedback. The tip deflection is proportional to the energy absorbed, and it allows extraction of spectroscopic information with nanoscale resolution, many-fold better than the diffraction limit. Topological images and chemical images are obtained simultaneously.

  4. Masthead

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      Masthead: (Small 3/2013)

      Article first published online: 1 FEB 2013 | DOI: 10.1002/smll.201370018

  5. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Review
    8. Communications
    9. Full Papers
    1. You have free access to this content
      Contents: (Small 3/2013) (pages 335–340)

      Article first published online: 1 FEB 2013 | DOI: 10.1002/smll.201370019

  6. Review

    1. Top of page
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    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Review
    8. Communications
    9. Full Papers
    1. How Do the Electrical Properties of Graphene Change with its Functionalization? (pages 341–350)

      T. S. Sreeprasad and Vikas Berry

      Article first published online: 21 NOV 2012 | DOI: 10.1002/smll.201202196

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      Functionalization of graphene changes its electrical properties. This review provides an integrative model which details the mechanisms by which the electrical properties of graphene are influenced by functionalization. These mechanisms influence the electrical attributed of graphene such as carrier concentration, mobility, doping polarity, and carrier transport. The modes of functionalization discussed are covalent, π−π interfacing, physisorption, and lattice-substitution.

  7. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Review
    8. Communications
    9. Full Papers
    1. Nanoengineered Colloidal Probes for Raman-based Detection of Biomolecules inside Living Cells (pages 351–356)

      Alexey Yashchenok, Admir Masic, Dmitry Gorin, Bong Sup Shim, Nicholas A. Kotov, Peter Fratzl, Helmuth Möhwald and Andre Skirtach

      Article first published online: 9 OCT 2012 | DOI: 10.1002/smll.201201494

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      Gold nanoparticle aggregate carbon nanotube functionalized colloidal particles serve as an efficient platform for probing the intracellular environment. The probes provide the means of effective localization of signal and detection of molecular fingerprints of biomolecules in living cells. The approach demonstrated in this work opens significant opportunities in molecular imaging as well as intracellular sensing and trafficking.

    2. Artificial Cytoskeletal Structures Within Enzymatically Active Bio-inorganic Protocells (pages 357–362)

      Ravinash Krishna Kumar, Mei Li, Sam N. Olof, Avinash J. Patil and Stephen Mann

      Article first published online: 2 OCT 2012 | DOI: 10.1002/smll.201201539

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      The fabrication of enzymatically active, semi-permeable bio-inorganic protocells capable of self-assembling a cytoskeletal-like interior and undergoing small-molecule dephosphorylation reactions is described. Reversible disassembly of an amino acid-derived supramolecular hydrogel within the internalized reaction space is used to tune the enzymatic activity of the nanoparticle-bounded inorganic compartments.

    3. Electronic Polymers and DNA Self-Assembled in Nanowire Transistors (pages 363–368)

      Mahiar Hamedi, Anders Elfwing, Roger Gabrielsson and Olle Inganäs

      Article first published online: 11 OCT 2012 | DOI: 10.1002/smll.201201771

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      Aqueous self-assembly of DNA and molecular electronic materials can lead to the creation of innumerable copies of identical devices, and inherently programmed complex nanocircuits. Here self-assembly of a water soluble and highly conducting polymer PEDOT-S with DNA in aqueous conditions is shown. Orientation and assembly of the conducting DNA/PEDOT-S complex into electrochemical DNA nanowire transistors is demonstrated.

    4. Soft Elastomeric Nanopillar Stamps for Enhancing Absorption in Organic Thin-Film Solar Cells (pages 369–374)

      Jerome K. Hyun, Changui Ahn, Hyunbum Kang, Hyeong Jun Kim, Junyong Park, Ki-Hyun Kim, Chi Won Ahn, Bumjoon J. Kim and Seokwoo Jeon

      Article first published online: 9 OCT 2012 | DOI: 10.1002/smll.201201881

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      An elastomeric poly(dimethylsiloxane) (PDMS) block engraved with periodically arrayed nanopillars serves as a transferable light-trapping stamp for encapsulated organic thin-film solar cells. Diffracted light rays from the stamp interfere with one another and self-focus onto the active layer of the solar cell, generating enhanced absorption, as indicated in the current density–voltage measurements.

    5. Self-Sorting of Deformable Particles in an Asynchronous Logic Microfluidic Circuit (pages 375–381)

      Marco A. Cartas-Ayala, Mohamed Raafat and Rohit Karnik

      Article first published online: 15 OCT 2012 | DOI: 10.1002/smll.201201422

      Thumbnail image of graphical abstract

      A microfluidic circuit can automatically sort deformable particles based on the hydrodynamic resistance that the particles induce in a constrained microfluidic channel while flowing through it.

    6. Graphene Oxide Scrolls on Hydrophobic Substrates Fabricated by Molecular Combing and Their Application in Gas Sensing (pages 382–386)

      Hai Li, Jumiati Wu, Xiaoying Qi, Qiyuan He, Cipto Liusman, Gang Lu, Xiaozhu Zhou and Hua Zhang

      Article first published online: 15 OCT 2012 | DOI: 10.1002/smll.201202358

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      Well-aligned graphene oxide (GO) scrolls are prepared through the controlled folding/scrolling of single-layer GO sheets using molecular combing on hydrophobic substrates, such as aged gold substrate, polydimethylsiloxane film, poly(L-lactic acid) film, and octadecyltrimethoxysilane-modified silicon dioxide. As a proof of concept, the gas sensor fabricated with a single reduced GO scroll is used to detect NO2 gas with a concentration as low as 0.4 ppm.

    7. Exposure to Titanium Dioxide Nanoparticles Induces Autophagy in Primary Human Keratinocytes (pages 387–392)

      Yun Zhao, Josephine L. C. Howe, Zhang Yu, David Tai Leong, Justin Jang Hann Chu, Joachim Say Chye Loo and Kee Woei Ng

      Article first published online: 23 OCT 2012 | DOI: 10.1002/smll.201201363

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      Understanding the mechanisms of cell-nanomaterial interactions is vital in harnessing the potential of using nanomaterials in biomedical applications. By immuno-labeling of LC3 and TEM analysis, it is found that titanium dioxide nanoparticles are internalized by human keratinocytes and induce autophagy. Autophagy appears to play a cytoprotective role in response to toxicity influence exerted by the nanoparticles.

  8. Full Papers

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Review
    8. Communications
    9. Full Papers
    1. Resolving Sub-Molecular Binding and Electrical Switching Mechanisms of Single Proteins at Electroactive Conducting Polymers (pages 393–401)

      A. Gelmi, M. J. Higgins and G. G. Wallace

      Article first published online: 17 OCT 2012 | DOI: 10.1002/smll.201201686

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      An atomic force microscope (AFM) tip is functionalized with fibronectin protein and interacts with a conducting polymer electrode comprising a conjugated backbone with entrapped dopants such as chondroitin sulphate, hyaluronic acid, or dextran sulfate. The conducting polymer operates as the working electrode in a 3-electrode electrochemical cell, including auxiliary and reference electrodes, positioned under the AFM. Force spectroscopy measurements are performed as a function of an applied voltage to study biomolecular interactions under electrical control.

    2. Nanostructured Superhydrophobic Substrates Trigger the Development of 3D Neuronal Networks (pages 402–412)

      Tania Limongi, Fabrizia Cesca, Francesco Gentile, Roberto Marotta, Roberta Ruffilli, Andrea Barberis, Marco Dal Maschio, Enrica Maria Petrini, Stefania Santoriello, Fabio Benfenati and Enzo Di Fabrizio

      Article first published online: 2 OCT 2012 | DOI: 10.1002/smll.201201377

      Thumbnail image of graphical abstract

      A novel method for culturing primary mouse hippocampal neurons and neuron-astrocyte co-cultures using superhydrophobic substrates with characteristic lengths falling into the microscale range and surface patterning in the nano-range is developed. This new culture method fosters neuronal growth and differentiation in an open scaffold, by reducing the interactions with the substrate and maximizing the physiological processes of cell-cell adhesion and synapse formation.

    3. A Galvanic Replacement Route to Prepare Strongly Fluorescent and Highly Stable Gold Nanodots for Cellular Imaging (pages 413–420)

      Chuanxi Wang, Yu Wang, Lin Xu, Xiaodong Shi, Xiangwei Li, Xiaowei Xu, Hongchen Sun, Bai Yang and Quan Lin

      Article first published online: 8 OCT 2012 | DOI: 10.1002/smll.201201849

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      A new synthetic route for the preparation of strongly fluorescent gold nanodots (GNDs) through galvanic replacement is developed. The resultant GNDs show excellent photoluminescence properties with high photo-, time-, metal- and pH-stability. The as-prepared GNDs exhibit good dispersion in aqueous solution, favorable biocompatibility, and could be used as nanoprobes for cells.

    4. Site-Specific Modification of Adeno-Associated Viruses via a Genetically Engineered Aldehyde Tag (pages 421–429)

      Yarong Liu, Yun Fang, Yu Zhou, Ebrahim Zandi, Chi-Lin Lee, Kye-Il Joo and Pin Wang

      Article first published online: 5 OCT 2012 | DOI: 10.1002/smll.201201661

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      An aldehyde moiety can be genetically incorporated onto the capsid surface of adeno-associated viruses. This chemical handle can be selectively modified through bioorthogonal conjugation chemistry to functionally outfit virus coats with antibodies and peptides for targeted gene delivery, and labelling agents for imaging studies.

    5. Amorphous Silica Nanoparticles Promote Monocyte Adhesion to Human Endothelial Cells: Size-Dependent Effect (pages 430–438)

      Dorota Napierska, Rozenn Quarck, Leen C. J. Thomassen, Dominique Lison, Johan A. Martens, Marion Delcroix, Benoit Nemery and Peter H. Hoet

      Article first published online: 8 OCT 2012 | DOI: 10.1002/smll.201201033

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      The effect of amorphous silica nanoparticles (SiO2-NPs) of different sizes on endothelial cells function is examined in vitro. Human endothelial cells are incubated with SiO2-NPs in the presence or not of triple cell co-cultures. The results show that SiO2-NPs enhance the adhesive properties of endothelial cells. This process is modified by the size of the nanoparticle and the presence of other co-cultured cells.

    6. Chemical Imaging Beyond the Diffraction Limit: Experimental Validation of the PTIR Technique (pages 439–445)

      Basudev Lahiri, Glenn Holland and Andrea Centrone

      Article first published online: 4 OCT 2012 | DOI: 10.1002/smll.201200788

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      Quantitative chemical imaging with nanoscale resolution is demonstrated using a photothermal induced resonance technique by measuring the sample thermal expansion induced by the absorption of IR light with an atomic force microscopy tip. Lateral resolution, sensitivity, and linearity of the technique is evaluated with lithographically defined samples.

      Corrected by:

      Corrigendum: Chemical Imaging Beyond the Diffraction Limit: Experimental Validation of the PTIR Technique

      Vol. 9, Issue 11, 1876, Article first published online: 3 JUN 2013

    7. A Versatile Multicomponent Assembly via β-cyclodextrin Host–Guest Chemistry on Graphene for Biomedical Applications (pages 446–456)

      Haiqing Dong, Yongyong Li, Jinhai Yu, Yanyan Song, Xiaojun Cai, Jiaqiang Liu, Jiaming Zhang, Rodney C. Ewing and Donglu Shi

      Article first published online: 9 OCT 2012 | DOI: 10.1002/smll.201201003

      Thumbnail image of graphical abstract

      A unique carrier system is engineered from β-cyclodextrin (β-CD) as a unit module assembled in a multiple fashion onto graphene nanosheets (GNS). Such carrier is capable of accommodating a variety of functional or biological “guest” molecules, providing needed functionalities such as fluorescence for in vivo imaging, anticancer drug for therapy, or target moieties for cell targeting.

    8. In-Vitro Permeability of Neutral Polystyrene Particles via Buccal Mucosa (pages 457–466)

      Birgit Johanna Teubl, Claudia Meindl, Andreas Eitzlmayr, Andreas Zimmer, Eleonore Fröhlich and Eva Roblegg

      Article first published online: 30 OCT 2012 | DOI: 10.1002/smll.201201789

      Thumbnail image of graphical abstract

      In the buccal mucosa, the uptake of neutral polystyrene nanoparticles (PP) is size-dependent. Compared to 25 and 50 nm particles, 200 nm PP particles penetrate into deeper regions of the mucosa. This is attributed to the structure of the buccal mucosa, i.e., mucus layer and microplicae. The particles permeate the mucus layer and deposit in ridge-like folds of superficial buccal cells. Thus, the effects of thermodynamic driving forces and/or interparticle electrostatic repulsion are enhanced and cellular uptake might be reduced for smaller particle sizes.

    9. Multi-Fuel Driven Janus Micromotors (pages 467–471)

      Wei Gao, Mattia D'Agostino, Victor Garcia-Gradilla, Jahir Orozco and Joseph Wang

      Article first published online: 11 OCT 2012 | DOI: 10.1002/smll.201201864

      Thumbnail image of graphical abstract

      The multi-fuel operation of a hybrid micromotor is illustrated using Al/Pd Janus microspheres. These Al/Pd Janus microspheres are propelled efficiently in alkaline, acid, and hydrogen peroxide fuel environments by thrusts of hydrogen or oxygen bubbles generated at their Al and Pd hemispheres. High speeds and long lifetimes are demonstrated in these different media along with an adaptive fuel-switching operation. The new micromotor holds considerable promise for diverse applications in different chemical environments.

    10. Gold Nanoparticles Downregulate Interleukin-1β-Induced Pro-Inflammatory Responses (pages 472–477)

      Vadim V. Sumbayev, Inna M. Yasinska, Cesar Pascual Garcia, Douglas Gilliland, Gurprit S. Lall, Bernhard F. Gibbs, David R. Bonsall, Luca Varani, François Rossi and Luigi Calzolai

      Article first published online: 30 OCT 2012 | DOI: 10.1002/smll.201201528

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      Interleukin 1 beta (IL-1β)-dependent inflammatory disorders pose a serious medical burden worldwide. Here it is shown for the first time that gold nanoparticles specifically downregulate cellular responses induced by IL-1β. These results indicate that the anti- inflammatory activity of gold nanoparticles is associated with an extracellular interaction with IL-1β, thus opening potentially novel options for further therapeutic applications.

    11. A Joint Experimental and Computational Search for Authentic Nano-electrocatalytic Effects: Electrooxidation of Nitrite and L-Ascorbate on Gold Nanoparticle-Modified Glassy Carbon Electrodes (pages 478–486)

      Ying Wang, Kristopher R. Ward, Eduardo Laborda, Chris Salter, Alison Crossley, Robert M. J. Jacobs and Richard G. Compton

      Article first published online: 2 NOV 2012 | DOI: 10.1002/smll.201201670

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      The comparison of simulated and experimental voltammograms enables the detection of changes of the electron transfer kinetics at the nanoscale. This approach is applied to verify electrocatalytic nanoeffects of gold nanoparticles for the electrooxidation of L-ascorbate and to discount electrocatalysis for the electrooxidation of nitrite.

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