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- UNKNOWN 6(5):261 (2011)
Nature Nanotechnology | Research Highlights Our choice from the recent literature Journal name:Nature NanotechnologyVolume: 6,Page:261Year published:(2011)DOI:doi:10.1038/nnano.2011.73Published online06 May 2011 Read the full article * Instant access to this article: US$32Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Nano Lett. 10.1021/nl200384p (2011) Superparamagnetic nanoparticles have been used in affinity assays to detect biomolecules. Magnetic nanoparticles that have captured target molecules in a fluid sample form clusters that can be monitored through changes either in the optical transmittance of the sample or in the transverse relaxation time of the clusters in nuclear magnetic resonance. However, these measurements cannot resolve few-particle clusters against a large background of single nanoparticles and therefore limit the sensitivity and speed of the assay. Menno Prins and colleagues at Philips Research and Eindhoven University of Technology have now developed a technique to selectively actuate, characterize and detect clusters of magnetic nanoparticles for highly sensitive and rapid detection of biomolecules. View full text Read the full article * Instant access to this article: US$32Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Additional data - Energy storage: Batteries take charge
- UNKNOWN 6(5):262-263 (2011)
Nature Nanotechnology | News and Views Energy storage: Batteries take charge * Andreas Stein1Journal name:Nature NanotechnologyVolume: 6,Pages:262–263Year published:(2011)DOI:doi:10.1038/nnano.2011.69Published online06 May 2011 Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. A nanostructured electrode can allow a lithium-ion battery to charge to 90% of maximum capacity in two minutes. View full text Subject terms: * Electronic properties and devices * Nanomaterials * Synthesis and processing Author information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Affiliations * Andreas Stein is in the Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA Corresponding author Correspondence to: * Andreas Stein Author Details * Andreas Stein Contact Andreas Stein Search for this author in: * NPG journals * PubMed * Google Scholar Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Additional data - Nanotoxicology: Nanoparticles versus the placenta
- UNKNOWN 6(5):263-264 (2011)
Nature Nanotechnology | News and Views Nanotoxicology: Nanoparticles versus the placenta * Jeffrey A. Keelan1Journal name:Nature NanotechnologyVolume: 6,Pages:263–264Year published:(2011)DOI:doi:10.1038/nnano.2011.65Published online06 May 2011 Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Pregnant mice treated 70-nm silica nanoparticles or 35-nm titanium dioxide nanoparticles suffer damage to the placenta and fetus, whereas larger nanoparticles do not have an adverse impact. View full text Subject terms: * Nanoparticles * Environmental, health and safety issues Author information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Affiliations * Jeffrey Keelan is in the School of Women's and Infants' Health, University of Western Australia at King Edward Memorial Hospital, Subiaco, Perth, Western Australia 6009, Australia * Jeffrey A. Keelan Corresponding author Correspondence to: * Jeffrey A. Keelan Author Details * Jeffrey A. Keelan Contact Jeffrey A. Keelan Search for this author in: * NPG journals * PubMed * Google Scholar Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Additional data - Catalysis: Acidic ideas for hydrogen storage
- UNKNOWN 6(5):265-266 (2011)
Nature Nanotechnology | News and Views Catalysis: Acidic ideas for hydrogen storage * Albert Boddien1 * Henrik Junge1 * Affiliations * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:265–266Year published:(2011)DOI:doi:10.1038/nnano.2011.70Published online06 May 2011 Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Core–shell nanoparticles can be used to release hydrogen from formic acid and could provide a convenient method for storing hydrogen. View full text Subject terms: * Nanoparticles * Structural properties Author information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Affiliations * Albert Boddien and Henrik Junge are in the Leibniz-Institute for Catalysis, University of Rostock, 18059 Rostock, Germany Corresponding author Correspondence to: * Henrik Junge Author Details * Albert Boddien Search for this author in: * NPG journals * PubMed * Google Scholar * Henrik Junge Contact Henrik Junge Search for this author in: * NPG journals * PubMed * Google Scholar Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Additional data - Biosensors: Magnets tackle kinetic questions
- UNKNOWN 6(5):266-267 (2011)
Nature Nanotechnology | News and Views Biosensors: Magnets tackle kinetic questions * Shawn P. Mulvaney1Journal name:Nature NanotechnologyVolume: 6,Pages:266–267Year published:(2011)DOI:doi:10.1038/nnano.2011.67Published online06 May 2011 Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Interactions between biomolecules can be probed with the help of technology that was developed for reading data stored on magnetic disk drives. View full text Subject terms: * Nanosensors and other devices Author information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Affiliations * Shawn P. Mulvaney is in the Chemistry Division, U.S. Naval Research Laboratory, Washington DC 20375, USA Corresponding author Correspondence to: * Shawn P. Mulvaney Author Details * Shawn P. Mulvaney Contact Shawn P. Mulvaney Search for this author in: * NPG journals * PubMed * Google Scholar Read the full article * Instant access to this article: US$18Buy now * Subscribe to Nature Nanotechnology for full access: SubscribeLogin for existing subscribers Additional access options: * Use a document delivery service * Login via Athens * Purchase a site license * Institutional access * British Library Document Supply Centre * Infotrieve * Thompson ISI Document Delivery * You can also request this document from your local library through inter-library loan services. Additional data - Building plasmonic nanostructures with DNA
- UNKNOWN 6(5):268-276 (2011)
Nature Nanotechnology | Review Building plasmonic nanostructures with DNA * Shawn J. Tan1 * Michael J. Campolongo1 * Dan Luo1 * Wenlong Cheng2 * Affiliations * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:268–276Year published:(2011)DOI:doi:10.1038/nnano.2011.49Published online17 April 2011 Abstract * Abstract * Author information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Plasmonic structures can be constructed from precise numbers of well-defined metal nanoparticles that are held together with molecular linkers, templates or spacers. Such structures could be used to concentrate, guide and switch light on the nanoscale in sensors and various other devices. DNA was first used to rationally design plasmonic structures in 1996, and more sophisticated motifs have since emerged as effective and versatile species for guiding the assembly of plasmonic nanoparticles into structures with useful properties. Here we review the design principles for plasmonic nanostructures, and discuss how DNA has been applied to build finite-number assemblies (plasmonic molecules), regularly spaced nanoparticle chains (plasmonic polymers) and extended two- and three-dimensional ordered arrays (plasmonic crystals). View full text Subject terms: * Nanobiotechnology * Nanoparticles * Photonic structures and devices Figures at a glance * Figure 1: A 'periodic table' of plasmonic atoms. Plasmonic nanoparticles can be categorized based on geometrical parameters. Rows one to five contain spherical shapes12, rod-like shapes13, 14, 15, 16, 17, 18, 19, 2D polygons20, 21, 22, 23, 24, 25, 3D polyhedrons26, 27, 28, 29, 30 and branched shapes31, 32, 33. From left to right in each row, particles become geometrically higher-ordered in terms of aspect ratios, number of sides and facets, or number of branches. The last particle in each row has a hollow structure. Row six contains nanoparticles of various complexities32, 34, 35, 36, 37, 38. Row seven contains various other hollow polygonal and polyhedral nanoparticles7, 30, 39, 40, 41, 42, 43. Some images have been cropped, rotated, recoloured and/or had their backgrounds filled in; see the original papers for scale bars and other information. Figure reproduced with permission from: 2–9, 13–16, 19, 23–27, 29, 31, 35–37, 39, 40, refs 12, 13, 14, 15, 16, 17, 18, 19, 23, 23, 24, 25, 28, 30, 31, 31, 31, 31, 33, 35, 3! 8, 34, 39, 30, 41 respectively, © 2006, 2007, 2008, 2009, 2006, 2008, 2008, 2006, 2005, 2005, 2005, 2004, 2008, 2002, 2003, 2003, 2003, 2003, 2009, 2010, 2008, 2004, 2008, 2002, 2006 respectively ACS; 10, 43, refs 20, 43 respectively © 2001, 2002 respectively AAAS; 11, 22, 34, refs 21, 29, 37 respectively, © 2005, 2010, 2007 respectively RSC; 12, 17, 21, 28, 30, 33, 34, 42, refs 22, 26, 26, 32, 36, 32, 32, 42 respectively © 2010, 2004, 2004, 2008, 2007, 2008, 2008, 2009 respectively Wiley; 18, 20, 41, refs 27, 27, 7 © 2007, 2007, 2009 NPG; 38, ref. 40, © 2007 Elsevier. * Figure 2: Schematic of plasmonic nanostructures assembled from libraries of plasmonic atoms with various DNA motifs. A vast library of plasmonic atoms can be synthesized using wet-chemistry approaches; various DNA motifs can be created using DNA nanotechnology; the plasmonic atoms and DNA can then be used to rationally design and synthesize a range of plasmonic nanostructures. * Figure 3: Plasmonic nanostructures rationally organized from metallic 'nanoparticle atoms'. These spatially directed assemblies include homomeric molecules (panels 1–681, 98, 102, 106, 110, 123; 13–1749, 97), heteromeric molecules (panels 7–1283, 98, 101, 102, 103, 104; 1895), linear 'polymer' chains (panels 19–2448, 111, 115, 116), 2D crystalline patterns (panels 25–2946, 87, 94, 117) and 3D nanoparticle crystals (panels 3082 and 3186). Some images have been cropped, rotated, recoloured and/or had their backgrounds filled in; see the original papers for scale bars and other information. Figure reproduced with permission from: 1, 8, 13–15, 17, 24, 31, refs 98, 98, 49, 49, 49, 49, 111, 86 respectively, © 1999, 1999, 2010, 2010, 2010, 2010, 2005, 2010 respectively Wiley; 2, 7, 11, 16, 23, 28–30, refs 81, 101, 83, 97, 116, 117, 87, 82 respectively, © 1996, 2010, 2009, 2010, 2010, 2008, 2009, 2010 respectively NPG; 3–6, 9, 10, 12, 18, 19, 25–27, refs 106, 102, 110, 123, 102, 104, 103, 95, 115, 46, 94, 94 respectively, © 2007, 2009, 2009, 2009, 2009! , 2006, 1998, 2010, 2004, 2004, 2006, 2006 respectively ACS; 20–22, ref. 48, © 2009 AAAS. Author information * Abstract * Author information Affiliations * Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, USA, * Shawn J. Tan, * Michael J. Campolongo & * Dan Luo * Department of Chemical Engineering, Monash University, Clayton, Victoria 3150, Australia. * Wenlong Cheng Competing financial interests The authors declare no competing financial interests. Corresponding author Correspondence to: * Wenlong Cheng Author Details * Shawn J. Tan Search for this author in: * NPG journals * PubMed * Google Scholar * Michael J. Campolongo Search for this author in: * NPG journals * PubMed * Google Scholar * Dan Luo Search for this author in: * NPG journals * PubMed * Google Scholar * Wenlong Cheng Contact Wenlong Cheng Search for this author in: * NPG journals * PubMed * Google Scholar Additional data - Three-dimensional bicontinuous ultrafast-charge and -discharge bulk battery electrodes
- UNKNOWN 6(5):277-281 (2011)
Nature Nanotechnology | Letter Three-dimensional bicontinuous ultrafast-charge and -discharge bulk battery electrodes * Huigang Zhang1 * Xindi Yu1 * Paul V. Braun1 * Affiliations * Contributions * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:277–281Year published:(2011)DOI:doi:10.1038/nnano.2011.38Received21 October 2010Accepted24 February 2011Published online20 March 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Rapid charge and discharge rates have become an important feature of electrical energy storage devices, but cause dramatic reductions in the energy that can be stored or delivered by most rechargeable batteries (their energy capacity)1, 2, 3, 4, 5, 6, 7. Supercapacitors do not suffer from this problem, but are restricted to much lower stored energy per mass (energy density) than batteries8. A storage technology that combines the rate performance of supercapacitors with the energy density of batteries would significantly advance portable and distributed power technology2. Here, we demonstrate very large battery charge and discharge rates with minimal capacity loss by using cathodes made from a self-assembled three-dimensional bicontinuous nanoarchitecture consisting of an electrolytically active material sandwiched between rapid ion and electron transport pathways. Rates of up to 400C and 1,000C for lithium-ion and nickel-metal hydride chemistries, respectively, are achieved ! (where a 1C rate represents a one-hour complete charge or discharge), enabling fabrication of a lithium-ion battery that can be 90% charged in 2 minutes. View full text Subject terms: * Electronic properties and devices * Nanomaterials * Synthesis and processing Figures at a glance * Figure 1: Bicontinuous battery electrode. , Schematic of a battery containing a bicontinuous cathode. , Illustration of the four primary resistances in a battery electrode. , Bicontinuous electrode fabrication process. The electrolytically active phase is yellow and the porous metal current collector is green. The electrolyte fills the remaining pores. * Figure 2: Bicontinuous electrode microstructure. SEM images of a bicontinuous three-dimensional electrode during each step of preparation. , Nickel inverse opal after electropolishing (1.8 µm colloidal particle template). , Cross-section of NiOOH/nickel composite cathode. , Cross-section of NiOOH/nickel cathode after cycling. , Nickel inverse opal after electropolishing (466 nm colloidal particle template). , MnO2/nickel composite cathode. , Lithiated MnO2/nickel composite cathode. * Figure 3: Ultrafast discharge and charge of the NiOOH electrode. , Discharge curves of NiOOH/nickel cathode at various C-rates. , Constant potential charge curves (0.45 V versus silver/AgCl) and 6C discharge curves after charging at constant potential for the indicated time. The curve labelled 'full charge' was charged galvanostatically at 1C. * Figure 4: Ultrafast discharge of the lithiated MnO2 cathode. The lithiated MnO2 cathode was discharged at C-rates ranging from 1.1 to 1,114C. * Figure 5: Lithium-ion battery ultrafast charge behaviour. Potentiostatic charging at 3.6 V for 60 s (blue), 120 s (green) and 800 s (red), and ~3C galvanostatic discharging of the prototype lithium-ion pouch battery after each charging cycle. Author information * Abstract * Author information * Supplementary information Affiliations * Department of Materials Science and Engineering, Materials Research Laboratory, and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA * Huigang Zhang, * Xindi Yu & * Paul V. Braun Contributions H.Z., X.Y. and P.V.B. designed the experiments. H.Z and X.Y. performed and analysed the experiments. H.Z., X.Y. and P.V.B. wrote the manuscript. P.V.B. supervised the project. Competing financial interests The authors declare no competing financial interests. Corresponding author Correspondence to: * Paul V. Braun Author Details * Huigang Zhang Search for this author in: * NPG journals * PubMed * Google Scholar * Xindi Yu Search for this author in: * NPG journals * PubMed * Google Scholar * Paul V. Braun Contact Paul V. Braun Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information PDF files * Supplementary information (1,494 KB) Supplementary information Additional data - Scalable nanostructured membranes for solid-oxide fuel cells
- UNKNOWN 6(5):282-286 (2011)
Nature Nanotechnology | Letter Scalable nanostructured membranes for solid-oxide fuel cells * Masaru Tsuchiya1, 2 * Bo-Kuai Lai2 * Shriram Ramanathan2 * Affiliations * Contributions * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:282–286Year published:(2011)DOI:doi:10.1038/nnano.2011.43Received22 November 2010Accepted01 March 2011Published online03 April 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg The use of oxide fuel cells and other solid-state ionic devices in energy applications is limited by their requirement for elevated operating temperatures, typically above 800 °C (ref. 1). Thin-film membranes allow low-temperature operation by reducing the ohmic resistance of the electrolytes2. However, although proof-of-concept thin-film devices have been demonstrated3, scaling up remains a significant challenge because large-area membranes less than ~100 nm thick are susceptible to mechanical failure. Here, we report that nanoscale yttria-stabilized zirconia membranes with lateral dimensions on the scale of millimetres or centimetres can be made thermomechanically stable by depositing metallic grids on them to function as mechanical supports. We combine such a membrane with a nanostructured dense oxide cathode to make a thin-film solid-oxide fuel cell that can achieve a power density of 155 mW cm–2 at 510 °C. We also report a total power output of more than 20 mW from ! a single fuel-cell chip. Our large-area membranes could also be relevant to electrochemical energy applications such as gas separation, hydrogen production and permeation membranes. View full text Subject terms: * Nanomaterials * Structural properties Figures at a glance * Figure 1: Schematic of constraints from KOH etch of silicon. ,, Comparison of area utilization between KOH-etched 100-μm-edge square membranes () and grid-supported 5 mm × 5 mm membranes (). Area utilization was increased from 1.4% to 54.3%. ,, Images of an array of ten 100 µm × 100 µm cells used in previous studies (reprinted from ref. 7, copyright (2010), with permission from Elsevier) () and a coupon with a 5 mm × 5 mm active area demonstrated in this study (). * Figure 2: Image of a 4-inch wafer with grid-supported µSOFCs. , Array of 5 mm × 5 mm etch holes viewed from the top (LSCF cathode side). , Various sizes of active μSOFCs fabricated on a 4-inch wafer. The largest etch hole shown here is 4 cm × 4 cm. , Optical micrograph of free-standing LSCF/YSZ membranes and platinum grids after RIE. Each circle is 100 µm in diameter, and the grid width is 10 µm. * Figure 3: SEM micrographs of grid-supported µSOFCs. , SEM micrograph of slightly buckled free-standing membranes before testing. , SEM micrograph of free-standing membranes after testing. , Magnified view of interface between free-standing membrane (marked 'LSCF surface') and the platinum grid. , Cross-sectional micrograph of μSOFCs after testing. * Figure 4: In situ observation of grid morphology during fuel-cell testing and power performance curves. ,, Optical micrographs taken from the cathode side near room temperature () and at 480 °C (). , Current voltage sweep of platinum-grid-supported 5 mm × 5 mm μSOFC at three different temperatures. The performance of a silver grid-supported cell is discussed in the Supplementary Information. Author information * Abstract * Author information * Supplementary information Affiliations * SiEnergy Systems LLC, Boston, Massachusetts, 02110, USA * Masaru Tsuchiya * Harvard School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, 02138, USA * Masaru Tsuchiya, * Bo-Kuai Lai & * Shriram Ramanathan Contributions M.T. planned, designed and conducted the experiments and data analysis, in collaboration with B.K.L. and S.R. M.T. and S.R. wrote the manuscript. All authors discussed the results and their interpretation. Competing financial interests The authors declare no competing financial interests. Corresponding author Correspondence to: * Masaru Tsuchiya Author Details * Masaru Tsuchiya Contact Masaru Tsuchiya Search for this author in: * NPG journals * PubMed * Google Scholar * Bo-Kuai Lai Search for this author in: * NPG journals * PubMed * Google Scholar * Shriram Ramanathan Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information PDF files * Supplementary information (1,383 KB) Supplementary information Additional data - Nanoscale Joule heating, Peltier cooling and current crowding at graphene–metal contacts
- UNKNOWN 6(5):287-290 (2011)
Nature Nanotechnology | Letter Nanoscale Joule heating, Peltier cooling and current crowding at graphene–metal contacts * Kyle L. Grosse1, 2 * Myung-Ho Bae2, 3 * Feifei Lian2, 3 * Eric Pop2, 3, 4 * William P. King1, 2, 4, 5 * Affiliations * Contributions * Corresponding authorsJournal name:Nature NanotechnologyVolume: 6,Pages:287–290Year published:(2011)DOI:doi:10.1038/nnano.2011.39Received27 January 2011Accepted24 February 2011Published online03 April 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg The performance and scaling of graphene-based electronics1 is limited by the quality of contacts between the graphene and metal electrodes2, 3, 4. However, the nature of graphene–metal contacts remains incompletely understood. Here, we use atomic force microscopy to measure the temperature distributions at the contacts of working graphene transistors with a spatial resolution of ~10 nm (refs 5, 6, 7, 8), allowing us to identify the presence of Joule heating9, 10, 11, current crowding12, 13, 14, 15, 16 and thermoelectric heating and cooling17. Comparison with simulation enables extraction of the contact resistivity (150–200 Ω µm2) and transfer length (0.2–0.5 µm) in our devices; these generally limit performance and must be minimized. Our data indicate that thermoelectric effects account for up to one-third of the contact temperature changes, and that current crowding accounts for most of the remainder. Modelling predicts that the role of current crowding will dimin! ish and the role of thermoelectric effects will increase as contacts improve. View full text Subject terms: * Electronic properties and devices * Nanometrology and instrumentation * Surface patterning and imaging Figures at a glance * Figure 1: Device layout. The temperature of the graphene device during device operation is overlaid on the topography. The device was biased with backgate voltage VG = 0 V, and square-wave input VDS = 1.5 V at 65 kHz and 50% duty (power, ~1.5 mW). Colder edges are consistent with heat sinking and higher edge carrier concentration30, 31 owing to fringing heat and electric field effects. * Figure 2: Measured and predicted contact heating and cooling. ,, Measured () and simulated () temperature profiles at the graphene–metal contact for a device with hole flow into (right arrows) and out of (left arrows) the contact. Operation is at VG = 0 V (Dirac voltage, V0 = 32 V) and VDS = 1, 1.5 and 2 V, both forward and reverse. Device dimensions are L = 5 µm, W = 4 µm, LC = 5 µm, and the edge of the graphene–palladium contact is at x = 2.5 µm. Inset to : resistance (R) including contacts versus VG for both experiment (symbols) and the model (line) used to fit the device mobility. * Figure 3: Relative contribution of contact effects. , Simulations showing relative contributions of Joule heating (JH), current crowding (CC) and the thermoelectric (TE) effect to the temperature distribution at the graphene–palladium contact at VDS = 1 V and VG = 0 V. Including current crowding ('CC + JH') leads to a more gradual temperature decrease than that of the Joule heating model alone, and adding in the thermoelectric term introduces heating and cooling that depends on current flow direction. All three components are necessary to match the experimental data in Fig. 2. Inset: schematic of current crowding at the graphene–metal contact (not to scale). , Heat generation per unit length (q′) as a function of position along the device. The separate contributions of Joule heating, current crowding and the thermoelectric effect to heat generation near the contact are shown. Joule heating dominates in the graphene sheet. In the contact, current crowding accounts for ~two-thirds and the thermoelectric effect for ~on! e-third of the temperature change, with the present parameters. * Figure 4: Contact temperature under varying conditions. , Comparison of predicted and measured temperature asymmetry ΔTASM at VDS = 1 V. ΔTASM is the maximum difference in temperature rise of the contact for forward and reverse current flows (Supplementary Fig. S6). Joule heating and current crowding effects are negligible, and the thermoelectric effect dominates the temperature asymmetry and can be used to extract the Seebeck coefficient (see main text and Supplementary Information). , Predictions of ΔTASM as a function of current density. , Contact temperature rise for the present device (ρC = 150 Ω μm2, μ = 3,230 cm2 V−1 s−1) and a future device with greatly improved contact resistance and mobility (ρC = 1 Ω μm2, μ = 2 × 104 cm2 V−1 s−1) at VDS = 1 V. The maximum and minimum temperature rises at the contacts are indicated by ΔTC,MAX and ΔTC,MIN, and the gap between the two curves is ΔTASM, shown by the arrows. The temperature changes owing to the thermoelectric effect at the contacts are enhanced in fu! ture devices. , Projected temperature profile along the channel of a 5-μm-long device with the improved parameters. Note the negative temperature change at the right contact, where the current crowding is now negligible and the thermoelectric cooling becomes dominant. Author information * Abstract * Author information * Supplementary information Affiliations * Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA * Kyle L. Grosse & * William P. King * Micro and Nanotechnology Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA * Kyle L. Grosse, * Myung-Ho Bae, * Feifei Lian, * Eric Pop & * William P. King * Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA * Myung-Ho Bae, * Feifei Lian & * Eric Pop * Beckman Institute for Advanced Studies, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA * Eric Pop & * William P. King * Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA * William P. King Contributions K.L.G. performed measurements and simulations. M-H.B. fabricated devices and assisted with simulations. E.P. implemented the computational model and physical interpretation, with help from F.L., while E.P. and W.P.K. conceived the experiments. All authors discussed the results. K.L.G., E.P. and W.P.K. co-wrote the manuscript. Competing financial interests The authors declare no competing financial interests. Corresponding authors Correspondence to: * Eric Pop or * William P. King Author Details * Kyle L. Grosse Search for this author in: * NPG journals * PubMed * Google Scholar * Myung-Ho Bae Search for this author in: * NPG journals * PubMed * Google Scholar * Feifei Lian Search for this author in: * NPG journals * PubMed * Google Scholar * Eric Pop Contact Eric Pop Search for this author in: * NPG journals * PubMed * Google Scholar * William P. King Contact William P. King Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information Movies * Supplementary information (1,574 KB) Supplementary movie PDF files * Supplementary information (1,786 KB) Supplementary information Additional data - Nanoparticles reduce nickel allergy by capturing metal ions
- UNKNOWN 6(5):291-295 (2011)
Nature Nanotechnology | Letter Nanoparticles reduce nickel allergy by capturing metal ions * Praveen Kumar Vemula1, 2, 3 * R. Rox Anderson4 * Jeffrey M. Karp1, 2, 3 * Affiliations * Contributions * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:291–295Year published:(2011)DOI:doi:10.1038/nnano.2011.37Received29 December 2010Accepted18 February 2011Published online03 April 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Approximately 10% of the population in the USA1, 2 suffer from nickel allergy3, 4, 5, and many are unable to wear jewellery or handle coins and other objects that contain nickel6, 7, 8, 9, 10. Many agents have been developed to reduce the penetration of nickel through skin11, 12, but few formulations are safe and effective13, 14, 15. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may b! e an effective way to limit the exposure to metal ions that can cause skin irritation. View full text Subject terms: * Nanomedicine * Nanoparticles Figures at a glance * Figure 1: Capture efficiency of nickel and other metals by CaCO3 and CaPO4 nanoparticles. , Plot of metal concentration released either from metal salt or metal wire in the presence or absence of nanoparticles. Metal concentration was measured using ICP-AES. Surface areas of CaCO3 and CaPO4 particles are 10.9 and 52.9 m2 g−1, respectively. , Quantities of nickel released into artificial sweat at different time points from uncoated nickel wires and from nickel wires coated with different sized CaCO3 nanoparticles. , XPS spectra of nickel sequestered by CaPO4 and CaCO3 particles, and NiSO4 salt. Arrows indicate shoulder peaks. , Plot of calcium ion concentration released from CaCO3 and CaPO4 particles in the presence and absence of metal ions such as nickel and zinc. In panels , and , values are the average of three independent experiments and all standard deviations are <5% of the average values. * Figure 2: Thin coating of CaCO3 or CaPO4 nanoparticles prevents penetration of nickel ions into the skin. , Schematic of nickel permeation experiment with and without a nanoparticle coating on full-thickness pig skin (size of nanoparticles, ~70 and ~100 nm for CaCO3 and CaPO4 particles, respectively). , SEM and elemental mapping images of vertically sectioned pig-skin before (left) and after (right) rinsing with water show that GRAS nanoparticles can capture nickel ions and prevent their permeation into skin. Control samples comprising glycerine-only-coated skin and uncoated skin did not result in nickel being prevented from penetrating into the skin. Scale bars in , 200 µm. * Figure 3: In vitro experiment using isolated pig skin. , SEM image of untreated (top) and CaCO3 nanoparticle-coated (bottom) pig skin showing the presence of the nanoparticle coating on the skin. , Graph showing the efficacy of nickel capture by nanoparticles. CaCO3 or CaPO4 particles in glycerine were applied to pig skin, placed into a diffusion chamber and subsequently exposed to nickel ions (0.05 M, 1.3% (wt/vol) NiSO4). After 48 h, the skin was removed, and unbound particles and nickel were removed by washing with phosphate buffer saline. Subsequently, skin was dissolved in a 1:1 mixture of HNO3 and H2SO4 and subjected to H2O2, and the nickel concentration in the solution was quantified using ICP-AES. In all cases, values are the average of three independent experiments and all standard deviations are <5% of the average values. * Figure 4: In vivo nickel challenge experiments. All animals were sensitized with NiSO4 solution. On day 14, mice were challenged with 0.4% NiSO4.6H2O into the left rear footpad, and saline was injected into the right rear footpad as a control. Swelling was measured with digital calipers up to 72 h post nickel challenge. Animals that exhibited sensitivity to nickel were randomized into three groups and on day 21, 45 μl of 20% NiSO4.6H2O solution was applied after applying either nothing 'untreated', 'glycerine' or 'NPs-in-glycerine' coating. Mice in the 'untreated' group received nickel without addition of glycerine or nanoparticles. Mice in the 'glycerine (vehicle)' group were treated daily with glycerine only before the application of nickel ions. Mice in the 'CaPO4 NPs in glycerine' group were treated with glycerine containing ~100 nm CaPO4 nanoparticles (20% wt/wt) daily before the application of nickel ions. All animals were evaluated at 0, 24, 48 and 72 h for nickel sensitivity (dermatitis sc! ore). , Dermatitis was evaluated by blinded observers on a scale from 0 to 5. ,, Temporal dermatitis score comparisons of glycerine (vehicle) treated and untreated mice (*P < 0.05) (), and between mice treated with CaPO4 nanoparticles in a glycerine coating and mice treated with glycerine only (vehicle) () show that the nanoparticle coating reduces the inflammatory response (*P < 0.05). Author information * Abstract * Author information * Supplementary information Affiliations * Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA * Praveen Kumar Vemula & * Jeffrey M. Karp * Harvard Stem Cell Institute, 1350 Massachusetts Avenue, Cambridge, Massachusetts 02138, USA * Praveen Kumar Vemula & * Jeffrey M. Karp * Harvard-MIT Division of Heath Sciences & Technology, 65 Landsdowne Street, Cambridge, Massachusetts 02139, USA * Praveen Kumar Vemula & * Jeffrey M. Karp * Laser and Cosmetic Dermatology Center and Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA * R. Rox Anderson Contributions P.K.V. and J.M.K. conceived and designed the experiments, analysed the data and co-wrote the manuscript. R.R.A. helped design the experiments and write the manuscript. Competing financial interests The authors declare no competing financial interests. Corresponding author Correspondence to: * Jeffrey M. Karp Author Details * Praveen Kumar Vemula Search for this author in: * NPG journals * PubMed * Google Scholar * R. Rox Anderson Search for this author in: * NPG journals * PubMed * Google Scholar * Jeffrey M. Karp Contact Jeffrey M. Karp Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information PDF files * Supplementary information (1,099 KB) Supplementary information Additional data - A stretchable carbon nanotube strain sensor for human-motion detection
- UNKNOWN 6(5):296-301 (2011)
Nature Nanotechnology | Article A stretchable carbon nanotube strain sensor for human-motion detection * Takeo Yamada1 * Yuhei Hayamizu1 * Yuki Yamamoto1 * Yoshiki Yomogida1 * Ali Izadi-Najafabadi1 * Don N. Futaba1 * Kenji Hata1, 2 * Affiliations * Contributions * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:296–301Year published:(2011)DOI:doi:10.1038/nnano.2011.36Received03 August 2010Accepted18 February 2011Published online27 March 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Devices made from stretchable electronic materials could be incorporated into clothing or attached directly to the body. Such materials have typically been prepared by engineering conventional rigid materials such as silicon, rather than by developing new materials. Here, we report a class of wearable and stretchable devices fabricated from thin films of aligned single-walled carbon nanotubes. When stretched, the nanotube films fracture into gaps and islands, and bundles bridging the gaps. This mechanism allows the films to act as strain sensors capable of measuring strains up to 280% (50 times more than conventional metal strain gauges), with high durability, fast response and low creep. We assembled the carbon-nanotube sensors on stockings, bandages and gloves to fabricate devices that can detect different types of human motion, including movement, typing, breathing and speech. View full text Subject terms: * Carbon nanotubes and fullerenes * Nanosensors and other devices Figures at a glance * Figure 1: SWCNT-film strain sensor. , Key steps in fabricating the SWCNT strain sensor. , Photograph of the SWCNT-film strain sensor under strain. , Relative change in resistance versus strain for the strain sensor (aligned SWCNTs, red), randomly oriented SWCNTs (blue) and conventional metal thin film (black). Inset: close-up of the low-strain region. , Relative change in resistance for the initial loading (red) and unloading (blue) cycle. Inset: enlarged unloading plot. , Relative change in resistance versus strain for multiple-cycle tests: 10 (red), 100 (blue), 1,000 (green) and 10,000 (black) cycles at 5–100% (sensor 1), 5–150% (sensor 2) and 5–200% (sensor 3) strain. The baselines of sensors 2 and 3 are raised by 5 and 10%, respectively. , Relative change in resistance (blue) in response to a 5–100% step function of mechanical strain. Inset: close-up of the overshoot. , Relative change in resistance (blue) during ~2.5 Hz frequency cycling between 2.0 and 5.4% strain (red). , Close-up of the final c! ycle of . , Initial loading (red) and unloading (blue) of relative change in resistance versus strain for the packaged sensor. Inset: image of the packaged sensor structure. * Figure 2: Fracturing mechanism of film. –, Images of the SWCNT film on initial loading. Scale bar, 100 µm. , SEM image of the fractural structure of the SWCNT film at 100% strain. Scale bar, 5 µm. Inset: three-dimensional image at 100% strain. , Low-resolution SEM image of homogeneous fracturing of the SWCNT film. Scale bar, 50 µm. , SEM image of the suspended bundles. Scale bar, 1 µm. , Average island width (blue) and gap (red) versus strain for initial loading. Error bars indicate standard deviation. ,, Paper model of the unstrained and strained states, respectively. * Figure 3: Properties of SWCNT film. –, Film surface morphology during the unloading–loading cycle. Scale bar, 100 µm. , Average island width (blue) and gap (red) versus strain for cycling following the conditioning step. Error bars indicate standard deviation. , Model of the basic circuit of the film. * Figure 4: Stretchable wearable devices. ,,, Photographs of a bandage strain sensor (), a strain sensor fixed to a stocking () and a data glove (). Inset to : Photograph of the sensor adhered to the throat. Inset to : close-up of the device. ,,,, Relative changes in resistance versus time for breathing, phonation (speech), knee motion and data glove configurations, respectively. Author information * Abstract * Author information * Supplementary information Affiliations * Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8565, Japan * Takeo Yamada, * Yuhei Hayamizu, * Yuki Yamamoto, * Yoshiki Yomogida, * Ali Izadi-Najafabadi, * Don N. Futaba & * Kenji Hata * Japan Science and Technology Agency (JST), Kawaguchi, 332-0012, Japan * Kenji Hata Contributions T.Y., Y.H. and K.H. conceived and designed the experiments. T.Y. and Yu.Y. performed the experiments. D.F. contributed to materials preparation, Yo.Y. and A.I. contributed to device demonstration. T.Y. and K.H. co-wrote the paper. Competing financial interests The authors declare no competing financial interests. Corresponding author Correspondence to: * Kenji Hata Author Details * Takeo Yamada Search for this author in: * NPG journals * PubMed * Google Scholar * Yuhei Hayamizu Search for this author in: * NPG journals * PubMed * Google Scholar * Yuki Yamamoto Search for this author in: * NPG journals * PubMed * Google Scholar * Yoshiki Yomogida Search for this author in: * NPG journals * PubMed * Google Scholar * Ali Izadi-Najafabadi Search for this author in: * NPG journals * PubMed * Google Scholar * Don N. Futaba Search for this author in: * NPG journals * PubMed * Google Scholar * Kenji Hata Contact Kenji Hata Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information Movies * Supplementary information (3,298 KB) Supplementary movie 1 * Supplementary information (1,022 KB) Supplementary movie 2 * Supplementary information (3,296 KB) Supplementary movie 3 PDF files * Supplementary information (1,614 KB) Supplementary information Additional data - Hydrogen production from formic acid decomposition at room temperature using a Ag–Pd core–shell nanocatalyst
- UNKNOWN 6(5):302-307 (2011)
Nature Nanotechnology | Article Hydrogen production from formic acid decomposition at room temperature using a Ag–Pd core–shell nanocatalyst * Karaked Tedsree1 * Tong Li2 * Simon Jones1 * Chun Wong Aaron Chan1 * Kai Man Kerry Yu1 * Paul A. J. Bagot2 * Emmanuelle A. Marquis2 * George D. W. Smith2 * Shik Chi Edman Tsang1 * Affiliations * Contributions * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:302–307Year published:(2011)DOI:doi:10.1038/nnano.2011.42Received05 January 2011Accepted01 March 2011Published online10 April 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Formic acid (HCOOH) has great potential as an in situ source of hydrogen for fuel cells, because it offers high energy density, is non-toxic and can be safely handled in aqueous solution. So far, there has been a lack of solid catalysts that are sufficiently active and/or selective for hydrogen production from formic acid at room temperature. Here, we report that Ag nanoparticles coated with a thin layer of Pd atoms can significantly enhance the production of H2 from formic acid at ambient temperature. Atom probe tomography confirmed that the nanoparticles have a core–shell configuration, with the shell containing between 1 and 10 layers of Pd atoms. The Pd shell contains terrace sites and is electronically promoted by the Ag core, leading to significantly enhanced catalytic properties. Our nanocatalysts could be used in the development of micro polymer electrolyte membrane fuel cells for portable devices and could also be applied in the promotion of other catalytic reacti! ons under mild conditions. View full text Subject terms: * Nanoparticles * Structural properties Figures at a glance * Figure 1: Plot of rates of formic acid decomposition monitored by 13C NMR over different metal colloid catalysts (2 × 10−4 mol in 600 µl in D2O versus d-band centre; size, ~2–4 nm, except Ag, 8 nm) and M-core Pd shell (1:1) catalysts. , Correlation with position of d-band centre of the metal. , Correlation with the work function of the M core, where M = fcc (111) Ag, Rh, Au, Ru and Pt or hexagonal close-packed (hcp) (0001) Ru. Ag, with the largest difference in work function in relation to Pd, gives the strongest electron promotion to the Pd shell. * Figure 2: Catalytic formic acid decomposition shows a strong dependence on the surface structure of the metal particle28, 29. A clear kinetic isotopic effect of kC–H/kC–D = 1.5 is observed, suggesting the rate-determining step is related to C–H cleavage, which depends on structural and electronic aspects of the surface M sites. Adsorption of formic acid on metal nanoparticles gives three modes of adsorbed formates identified by 13C NMR: bridging (bidenate), linear (monodenate) and multilinear (multimonodentate)27. The bridging formate is prevalent on large terrace sites, which is the precursor for CO2. The linear and multilinear modes on surface-unsaturated M sites (adatoms, corners, steps, kinks) on small particles give stronger chemisorption and CO formation, which leads to catalyst poisoning. , Summary of the interactions of bridging formate on a flat terrace of metal M sites. , Linear formate on isolated or low coordinated M sites. * Figure 3: Correlation of rate of formic acid decomposition and core–shell geometry. , UV–vis spectra of Ag, Pd and Ag@Pd nanoparticles at different mole ratios. Ag produces an intense, sharp and surface-sensitive plasmon peak at 420 nm when Ag atoms cluster on the surface. Pd only produces a broad absorption background at this region (not shown). Note the achievement of a complete core–shell morphology when the Ag:Pd ratio reaches 1:1. , Plot of rates of formic acid decomposition over Ag@Pd at different mole ratios Ag:Pd; the 1:1 ratio is an optimum. * Figure 4: Correlation of hydrogen production activity with electronic promotion from the Ag core to the Pd shell using a CO probe combined with a Fourier transform infrared (FTIR) technique. , Plot of volume of CO2/H2 gas liberation over time from a stirred tank reactor containing 10 ml of 1 M aqueous formic acid and 2.0 × 10−4 mol (0.021 g) of 1:1 Ag@Pd catalyst, compared with Ag/Pd alloy and pure Pd. , FTIR of the nanocatalysts presaturated with CO molecules at 1 atm. * Figure 5: APT data from Ag@Pd nanoparticles. –, Atom map () of an individual Ag@Pd nanoparticle, clearly showing the core–shell structure, and column sections of atom maps (,) taken through the Ag@Pd nanoparticles with as-synthesized compositions as indicated, showing the differences in shell thickness. , Composition profile of Ag and Pd through a 1:3 Ag@Pd core–shell nanoparticle, showing a pure Ag core with a 5–10 atomic layer thickness of Pd shell atoms. Author information * Abstract * Author information * Supplementary information Affiliations * Wolfson Catalysis Centre, Department of Chemistry, University of Oxford, Oxford, OX1 3QR, UK * Karaked Tedsree, * Simon Jones, * Chun Wong Aaron Chan, * Kai Man Kerry Yu & * Shik Chi Edman Tsang * Department of Materials, University of Oxford, Oxford OX1 3PH, UK * Tong Li, * Paul A. J. Bagot, * Emmanuelle A. Marquis & * George D. W. Smith Contributions K.T., S.J., C.W.A.C. and K.M.K.Y. contributed to material synthesis, testing and characterization. T.L., P.A.J.B., E.A.M. and G.D.W.S. contributed to atom probe tomography. S.C.E.T. initiated, supervised and coordinated the research. All authors discussed the results and commented on the manuscript. Competing financial interests The authors declare no competing financial interests. Corresponding author Correspondence to: * Shik Chi Edman Tsang Author Details * Karaked Tedsree Search for this author in: * NPG journals * PubMed * Google Scholar * Tong Li Search for this author in: * NPG journals * PubMed * Google Scholar * Simon Jones Search for this author in: * NPG journals * PubMed * Google Scholar * Chun Wong Aaron Chan Search for this author in: * NPG journals * PubMed * Google Scholar * Kai Man Kerry Yu Search for this author in: * NPG journals * PubMed * Google Scholar * Paul A. J. Bagot Search for this author in: * NPG journals * PubMed * Google Scholar * Emmanuelle A. Marquis Search for this author in: * NPG journals * PubMed * Google Scholar * George D. W. Smith Search for this author in: * NPG journals * PubMed * Google Scholar * Shik Chi Edman Tsang Contact Shik Chi Edman Tsang Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information PDF files * Supplementary information (4,738 KB) Supplementary information Additional data - A high-throughput label-free nanoparticle analyser
- UNKNOWN 6(5):308-313 (2011)
Nature Nanotechnology | Article A high-throughput label-free nanoparticle analyser * Jean-Luc Fraikin1 * Tambet Teesalu2 * Christopher M. McKenney1 * Erkki Ruoslahti2, 3 * Andrew N. Cleland1 * Affiliations * Contributions * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:308–313Year published:(2011)DOI:doi:10.1038/nnano.2011.24Received17 December 2010Accepted04 February 2011Published online06 March 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Synthetic nanoparticles and genetically modified viruses are used in a range of applications, but high-throughput analytical tools for the physical characterization of these objects are needed. Here we present a microfluidic analyser that detects individual nanoparticles and characterizes complex, unlabelled nanoparticle suspensions. We demonstrate the detection, concentration analysis and sizing of individual synthetic nanoparticles in a multicomponent mixture with sufficient throughput to analyse 500,000 particles per second. We also report the rapid size and titre analysis of unlabelled bacteriophage T7 in both salt solution and mouse blood plasma, using just ~1 × 10−6 l of analyte. Unexpectedly, in the native blood plasma we discover a large background of naturally occurring nanoparticles with a power-law size distribution. The high-throughput detection capability, scalable fabrication and simple electronics of this instrument make it well suited for diverse applicati! ons. View full text Subject terms: * Nanometrology and instrumentation * Nanoparticles * Nanosensors and other devices Figures at a glance * Figure 1: Device schematics and detector response. , Overall chip layout showing relative placement of the electrical and fluidic components of the device: external voltage bias electrodes (H, L) and sensing electrode (S); embedded nanometre-scale filters (F); fluid resistor (FR); nanoconstriction (NC); pressure-regulated fluidic ports (P1−P6). The nanoparticle suspension to be analysed (dark shading) enters the analyser at P2 and exits at P6, avoiding H and L. , Detail of boxed area in , showing the core sensing components. Nanoparticles in saline suspension flow in the direction of the arrows, and changes in the electrical potential of the fluid adjacent to the nanoconstriction are detected by the lithographed sensing electrode S. , Electrical equivalent circuit: a constant bias voltage Vh (Vl) is applied to electrode H (L). Resistors Ra and Rb represent the electrical resistance of the nanoconstriction and the fluidic resistor, respectively. Electrode S is capacitively coupled to the fluid through the electric double-la! yer capacitance CDL. Circuit elements Ra, Rb and CDL are measured directly (see Supplementary Information). , Output voltage Vout as a function of time as a single particle of nominal diameter 117 nm traverses the nanoconstriction, showing excellent time resolution and signal-to-noise ratio. The peak voltage change ΔVout is proportional to Vh − Vl and to the volume filling fraction of the particle in the nanoconstriction40 (see Supplementary Information). * Figure 2: Controlling particle flow. –, False-colour fluorescence micrographs (–) and scanning electron micrograph () showing the fluidic components of the analyser and control of particle flow. Fluorescent polystyrene nanoparticles (with diameters of ~200 nm) traverse the integrated nanofilter (), and the fluidic electrical resistor () before reaching the vicinity of the nanoconstriction (indicated by the arrow in ). The black region in is the sensing electrode. A single external pressure setting at port P5 selects the flow path and flow rate of the fluid, sending particles either to the waste channel P4 () or through the nanoconstriction (). , A representative PDMS nanoconstriction with lateral dimensions 250 × 250 nm2, and depth 290 nm. Scale bars in all panels are 10 µm. * Figure 3: Detection bandwidth. , Measured relative particle diameter as a function of transit time (full width at half maximum) on a logarithmic scale as 117 nm nanoparticles pass through the nanoconstriction, using a range of flow rates, showing high-fidelity detection and sizing for single-particle transit times as small as 2 µs. Solid curves indicate the expected signal attenuation for three different minimum sensor response times. , High-frequency equivalent circuit model of the sensor including the input resistance of the first-stage amplifier Rm and the stray capacitance Cs. Rp is the equivalent resistance of the parallel combination of the fluid resistances Ra and Rb with Rm. , Spectral density SN of the noise in Vout for zero voltage bias, normalized by the expected thermal Nyquist noise of the effective resistance Rp, from which we determine the detector electrical bandwidth fRC ≡ 1/2πRpCs ≈ 650 kHz. The spectrum was obtained by averaging ten Fourier transforms of Vout versus time. * Figure 4: Analysis of a polydisperse nanoparticle mixture. , Output voltage Vout versus time for a mixture of nanoparticles of different diameter (51 nm, 75 nm and 117 nm). Events marked with red circles cluster around three values of Vout (horizontal dashed black lines). , Histogram of effective diameters (40 s measurement). The 117 nm peak is used to calibrate the horizontal axis, relative to which the other peaks correspond to diameters of 52 nm and 79 nm. Separately normalized DLS measurements of each population are indicated by spline fits (dashed blue, green and red lines), as are measurements of the mixture (dashed black line). The scattering signal from the 117 nm particles dominates the DLS measurement of the mixture, and results in a nearly identical measurement to that of the pure 117 nm particle solution. Using the mean transit time of the 117 nm nanoparticles to estimate the fluid flow rate, we find the absolute number densities are within factors of ~0.5–1.2 of those calculated from the manufacturers' specifications ! (see main text). * Figure 5: Size and concentration measurements of unlabelled bacteriophage T7 in salt solution. , Output voltage Vout versus time for a 1 s measurement, showing direct detection of unlabelled bacteriophage T7 virions (~65 nm), with an admixture of 117 nm calibration particles. Events cluster around three values of Vout (horizontal dashed lines). , Histogram of effective diameters displaying two phage particle diameters (blue outline), in addition to the calibration particles (red outline). Outlines are Gaussian least-square fits. The mean effective diameters are 65 nm, which corresponds to T7 virion singlets, and 81 nm, an effective diameter corresponding to virion dimers, with ~10% of phage apparently in dimer form. A normalized DLS measurement of the pure phage sample (no calibration particles) is indicated by a spline fit (blue points and dashed line). * Figure 6: Particle size distribution and T7 phage detection in mouse blood. , Representative 1 s time trace of Vout while sampling mouse blood plasma with an admixture of calibration particles (diameter, 117 nm; control); trace shows detection of ≳1,300 particles. , Histogram of particle diameters obtained from the trace in , showing large numbers of particles at small diameters (≲60 nm). , Particle concentration as a function of particle volume for diameters from ~50 nm to 100 nm. The fit shown by the red line indicates the power-law dependence of concentration c on particle volume vp, with c ∝ vp−3.3. , Output voltage Vout versus time while sampling T7 phage-infected plasma. , Histogram of effective particle diameters, showing a peak in particle concentration at ~55 nm attributed to phage. , Number density distributions of the blank plasma (blue dashed), phage-infected plasma (green dot-dashed) and the difference (red solid). The position of the peak (red arrow) in the difference curve yields the measured diameter of the phage to be 55 nm.! Integration of the peak gives the measured phage concentration of 5.3 × 1010 particles per ml, near that obtained by biological titre (1.5 × 1010 pfu ml−1). Author information * Abstract * Author information * Supplementary information Affiliations * Department of Physics, University of California Santa Barbara, California 93106, USA * Jean-Luc Fraikin, * Christopher M. McKenney & * Andrew N. Cleland * Vascular Mapping Laboratory, Center for Nanomedicine, Sanford-Burnham Medical Research Institute at University of California Santa Barbara, California 93106-9610, USA * Tambet Teesalu & * Erkki Ruoslahti * Cancer Research Center, Sanford-Burnham Medical Research Institute La Jolla, California 92037, USA * Erkki Ruoslahti Contributions J.-L.F. fabricated the analyser, performed the experiments and analysed the data. J.-L.F. and A.N.C designed the analyser. J.-L.F., T.T. and A.N.C. designed the experiments with contributions from E.R. J.-L.F. and A.N.C. wrote the manuscript with contributions from T.T. T.T. performed the biological procedures, including phage synthesis. C.M.M. contributed to the fabrication of the fluidic mold. Competing financial interests The authors declare no competing financial interests. Corresponding author Correspondence to: * Andrew N. Cleland Author Details * Jean-Luc Fraikin Search for this author in: * NPG journals * PubMed * Google Scholar * Tambet Teesalu Search for this author in: * NPG journals * PubMed * Google Scholar * Christopher M. McKenney Search for this author in: * NPG journals * PubMed * Google Scholar * Erkki Ruoslahti Search for this author in: * NPG journals * PubMed * Google Scholar * Andrew N. Cleland Contact Andrew N. Cleland Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information PDF files * Supplementary information (734 KB) Supplementary information Additional data - Quantification of protein interactions and solution transport using high-density GMR sensor arrays
- UNKNOWN 6(5):314-320 (2011)
Nature Nanotechnology | Article Quantification of protein interactions and solution transport using high-density GMR sensor arrays * Richard S. Gaster1, 2 * Liang Xu3 * Shu-Jen Han4 * Robert J. Wilson3 * Drew A. Hall5 * Sebastian J. Osterfeld6 * Heng Yu6 * Shan X. Wang3, 5 * Affiliations * Contributions * Corresponding authorJournal name:Nature NanotechnologyVolume: 6,Pages:314–320Year published:(2011)DOI:doi:10.1038/nnano.2011.45Received29 December 2010Accepted08 March 2011Published online10 April 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg Monitoring the kinetics of protein interactions on a high-density sensor array is vital to drug development and proteomic analysis. Label-free kinetic assays based on surface plasmon resonance are the current gold standard, but they have poor detection limits, suffer from non-specific binding, and are not amenable to high-throughput analyses. Here, we show that magnetically responsive nanosensors that have been scaled to over 100,000 sensors per cm2 can be used to measure the binding kinetics of various proteins with high spatial and temporal resolution. We present an analytical model that describes the binding of magnetically labelled antibodies to proteins that are immobilized on the sensor surface. This model is able to quantify the kinetics of antibody–antigen binding at sensitivities as low as 20 zeptomoles of solute. View full text Subject terms: * Nanosensors and other devices Figures at a glance * Figure 1: GMR nanosensor and nanoparticle system for kinetic analysis. , Schematic representation of antibody–antigen binding. On the left, antibody labelled with a magnetic nanoparticle tag in solution at concentration Cs approaches the GMR sensor surface. When not bound, most diffusing magnetically labelled antibodies are too far from the GMR sensor to be detected. Antigens are immobilized on the sensor surface at an initial surface concentration of nmax. Once the magnetically labelled antibody binds to the antigen, as depicted on the right, the magnetic field from the magnetic tag is detected by the underlying, proximity-based GMR nanosensor. The captured antibody–antigen complex surface concentration is n. , Optical micrograph showing the GMR sensor architecture comprising 72 stripes connected in parallel and in series. Inset: SEM image of one stripe of the GMR sensor with several bound magnetic nanoparticle tags. , Schematic representation of a magnetically labelled antibody, drawn to scale. The magnetic tag comprises a dozen iron-oxid! e cores embedded in a dextran polymer and then functionalized with antibody or receptor. * Figure 2: Comparison of experimentally generated binding curves to kinetic model predictions. , Binding curves for anti-EpCAM antibody binding to EpCAM antigens immobilized on the surface. Dotted lines are predictions using the analytical model in equation (2); solid lines are experimental data obtained for surface loading amounts varying from 5 amol (nmax) to 20 zmol (nmax/256) in serial dilutions of 2×. The fitting error for all curves in this experiment to curves predicted by the model is R2 = 0.98. , Binding curves for MNP–anti-EpCAM antibody binding to 833 zmol (nmax/6) of EpCAM antigen immobilized on the sensor surface. Dotted lines show prediction using the analytical model and solid lines the experimental data obtained for MNP–anti-EpCAM (undiluted, and diluted 2× and 8×). The fitting error of all curves to the model is R2 = 0.96. The y-axis is presented as changes in magnetoresistance (MR) normalized to the initial MR in ppm. * Figure 3: The kinetic model can predict the number of protein binding events. , By fitting real-time binding curves to the model, it is possible to convert the signal generated from the GMR sensor into an absolute number of magnetic tags bound to the sensor surface. Here, EpCAM protein was loaded onto the sensors at a mass of 2.5 amol (nmax) and at masses serially diluted in twofold increments down to 78 zmol (nmax/64). At least three replica sensors were used for each dilution. After 20 min, incubation with the 20-fold diluted solution of MNP–anti-EpCAM antibody (C0/20), the solution was washed away to terminate the binding reaction. , Subsequently, a small section of the sensors was imaged with SEM (colour-coded boxes represent the different loading masses) to compare the number of MNPs bound in the experiment with that predicted by the model (). The SEM image of nmax/64 was not shown due to the low surface coverage of MNPs. The number of MNPs indicated above each binding curve in represents the number of MNPs predicted to have bound to each corre! sponding sensor. Dotted lines are predictions using the analytical model in equation (2) and solid lines are experimental data. * Figure 4: Visualization of spatiotemporal resolution of the sensor array. , Schematic depicting the GMR sensor array functionalized with monoclonal anti-CEA capture antibody (not to scale). The solution above the sensor array is composed of magnetically labelled anti-CEA detection antibodies. The schematic includes a pipette tip containing a solution of CEA protein before injection. , Once the CEA antigen is introduced into the solution above the sensor array, radial transport of CEA antigen from near the centre of the array is monitored in real time. Magnetically labelled detection antibodies capture CEA protein and bind to anti-CEA antibodies on the GMR sensor surface to form detectable sandwich structures. , Visualization of CEA protein surface concentration at different times using a high-density GMR sensor array. The units of the y-axis are presented in changes in MR normalized to the initial MR in ppm. Author information * Abstract * Author information * Supplementary information Affiliations * Department of Bioengineering, Stanford University, California 94305, USA * Richard S. Gaster * Medical Scientist Training Program, School of Medicine, Stanford University, California 94305, USA * Richard S. Gaster * Department of Materials Science and Engineering, Stanford University, California 94305, USA * Liang Xu, * Robert J. Wilson & * Shan X. Wang * IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA * Shu-Jen Han * Department of Electrical Engineering, Stanford University, California 94305, USA * Drew A. Hall & * Shan X. Wang * MagArray Inc., Sunnyvale, California 94089, USA * Sebastian J. Osterfeld & * Heng Yu Contributions R.S.G. and S.X.W designed the research. R.S.G. performed the research. R.S.G., R.J.W. and S.X.W developed the model. R.S.G., L.X., S.H., R.J.W., D.A.H., S.J.O., H.Y. and S.X.W. contributed analytical tools. R.S.G., R.J.W. and S.X.W analysed the data. S.J.O., L.X., S.H. and S.X.W. designed the magnetic sensor arrays. R.S.G. and H.Y. developed the biochemistry. R.S.G. and S.X.W. wrote the paper. Competing financial interests Stanford University has licensed part of the magnetic bioassay chip technology contained in this publication to MagArray Inc., an early stage startup company in Silicon Valley, USA. S.X.W, H.Y., and S.J.O. hold financial interests in MagArray in the form of stock options. Corresponding author Correspondence to: * Shan X. Wang Author Details * Richard S. Gaster Search for this author in: * NPG journals * PubMed * Google Scholar * Liang Xu Search for this author in: * NPG journals * PubMed * Google Scholar * Shu-Jen Han Search for this author in: * NPG journals * PubMed * Google Scholar * Robert J. Wilson Search for this author in: * NPG journals * PubMed * Google Scholar * Drew A. Hall Search for this author in: * NPG journals * PubMed * Google Scholar * Sebastian J. Osterfeld Search for this author in: * NPG journals * PubMed * Google Scholar * Heng Yu Search for this author in: * NPG journals * PubMed * Google Scholar * Shan X. Wang Contact Shan X. Wang Search for this author in: * NPG journals * PubMed * Google Scholar Supplementary information * Abstract * Author information * Supplementary information PDF files * Supplementary information (1,487 KB) Supplementary information Additional data - Silica and titanium dioxide nanoparticles cause pregnancy complications in mice
- UNKNOWN 6(5):321-328 (2011)
Nature Nanotechnology | Article Silica and titanium dioxide nanoparticles cause pregnancy complications in mice * Kohei Yamashita1, 2, 11 * Yasuo Yoshioka1, 2, 3, 11 * Kazuma Higashisaka1, 2 * Kazuya Mimura4 * Yuki Morishita1, 2 * Masatoshi Nozaki4 * Tokuyuki Yoshida1, 2 * Toshinobu Ogura1, 2 * Hiromi Nabeshi1, 2 * Kazuya Nagano2 * Yasuhiro Abe2 * Haruhiko Kamada2, 3 * Youko Monobe5 * Takayoshi Imazawa5 * Hisae Aoshima6 * Kiyoshi Shishido7 * Yuichi Kawai8 * Tadanori Mayumi8 * Shin-ichi Tsunoda2, 3, 9 * Norio Itoh1 * Tomoaki Yoshikawa1, 2 * Itaru Yanagihara4 * Shigeru Saito10 * Yasuo Tsutsumi1, 2, 3 * Affiliations * Contributions * Corresponding authorsJournal name:Nature NanotechnologyVolume: 6,Pages:321–328Year published:(2011)DOI:doi:10.1038/nnano.2011.41Received23 September 2010Accepted28 February 2011Published online03 April 2011 Abstract * Abstract * Author information * Supplementary information Article tools * Full text * Print * Email * Download PDF * Download citation * Order reprints * Rights and permissions * Share/bookmark * Connotea * CiteULike * Facebook * Twitter * Delicious * Digg The increasing use of nanomaterials has raised concerns about their potential risks to human health. Recent studies have shown that nanoparticles can cross the placenta barrier in pregnant mice and cause neurotoxicity in their offspring, but a more detailed understanding of the effects of nanoparticles on pregnant animals remains elusive. Here, we show that silica and titanium dioxide nanoparticles with diameters of 70 nm and 35 nm, respectively, can cause pregnancy complications when injected intravenously into pregnant mice. The silica and titanium dioxide nanoparticles were found in the placenta, fetal liver and fetal brain. Mice treated with these nanoparticles had smaller uteri and smaller fetuses than untreated controls. Fullerene molecules and larger (300 and 1,000 nm) silica particles did not induce these complications. These detrimental effects are linked to structural and functional abnormalities in the placenta on the maternal side, and are abolished when the surf! aces of the silica nanoparticles are modified with carboxyl and amine groups. View full text Subject terms: * Nanoparticles * Environmental, health and safety issues Figures at a glance * Figure 1: Biodistribution of nanoparticles in pregnant mice. , In vivo fluorescence images. Pregnant mice at GD16 were treated with 0.8 mg DY-676-labelled silica particles per mouse (nSP70, nSP300, mSP1000, nSP70-C or nSP70-N) or PBS (control), intravenously, through the tail vein. After 24 h, optical images of the whole body, maternal liver and placenta were acquired with a Xenogen IVIS 200 imaging system. –, TEM images of placentae and fetuses at GD18. Pregnant mice were treated intravenously with 0.8 mg per mouse of nSP70, nano-TiO2, nSP70-C or nSP70-N on two consecutive days (GD16 and GD17). Arrows indicate nanoparticles. These particles were present in placental trophoblast cells (,,,,,), fetal liver cells (,,,,,) and fetal brain cells (,,,,,). * Figure 2: Pregnancy complications in nSP70- or nano-TiO2-treated mice. Pregnant mice were treated intravenously with 0.8 mg per mouse of nSP70, nSP300, mSP1000, nano-TiO2, fullerene C60, nSP70-C, nSP70-N or PBS (control) on two consecutive days (GD16 and GD17). , Changes in maternal body weight. Maternal body weights were evaluated daily (n = 11–24). Statistically significant difference from control mice, *P < 0.05 and **P < 0.01 by ANOVA. –, Pregnancy complications. Uteri from mice were excised at GD18 (). Uterine weights () and fetal resorption rates () were evaluated (n = 11–24). Fetuses () and placentae () were excised from uteri. Fetal weights () and placental weights () were evaluated (n = 37–212). All data represent means ± s.e.m (*P < 0.05, **P < 0.01 versus value for control mice by ANOVA). * Figure 3: Pathological examination of placenta. , Schematic showing the differences between human and mouse placentae. –, Histological examination. Pregnant mice were treated intravenously with 0.8 mg per mouse of nSP70 or PBS (control) on two consecutive days (GD16 and GD17). At GD18, sections of placentae from PBS- (,,,) or nSP70-treated mice (,,,) were stained with H&E (–) or PAS (–). The solid box in indicates the presence of spiral arteries and canals. Panels , , , and are enlarged images of the areas within the dashed boxes in , , and , respectively. In and , dashed lines delineate the decidua (de), spongiotrophoblast layer (sp) and labyrinth layer (la). Spongiotrophoblast layers of PBS- () or nSP70-treated mice () were stained with TUNEL. Labyrinth layers of PBS- () or nSP70-treated mice () were stained with H&E. * Figure 4: Dysfunction of placentae. Pregnant mice were treated intravenously with 0.8 mg per mouse of nSP70, nSP300, mSP1000 or PBS (control) on two consecutive days (GD16 and GD17). –, At GD18, the area of the placenta () and the spongiotrophoblast layer () and the ratios of the spongiotrophoblast layer area to the total placental area () and of the labyrinth layer area to the total placental area () were assessed by examining the PAS-stained sections in Fig. 3f–i and were analysed quantitatively. The apoptotic index () was assessed by examining the TUNEL-stained sections in Fig. 3j,k and was quantitatively analysed. The surrounding length of the villi () in the labyrinth layers was assessed by examining the H&E-stained sections in Fig. 3l,m and was quantitatively analysed. All data represent means ± s.e.m. (n = 11–20; *P < 0.05 and **P < 0.01 by ANOVA). * Figure 5: Prevention of nSP70-induced pregnancy complications with heparin. Pregnant mice were treated intravenously with 0.8 mg per mouse of nSP70 or PBS (control) through the tail vein with or without heparin on two consecutive days (GD16 and GD17). , Changes in maternal body weights. Maternal body weights were evaluated daily (n = 10–15). Statistically significant difference from control mice, *P < 0.05 and **P < 0.01 by ANOVA. –, Analysis of pregnancy complications in nSP70-treated mice with or without heparin treatment. At GD18, uterine weights (), fetal resorption rates () and fetal weights () were evaluated (,, n = 10–15; , n = 55–89). All data represent means ± s.e.m., *P < 0.05 and **P < 0.01 by Student's t-tests. Author information * Abstract * Author information * Supplementary information Primary authors * These authors contributed equally to this work * Kohei Yamashita & * Yasuo Yoshioka Affiliations * Department of Toxicology and Safety Science, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan * Kohei Yamashita, * Yasuo Yoshioka, * Kazuma Higashisaka, * Yuki Morishita, * Tokuyuki Yoshida, * Toshinobu Ogura, * Hiromi Nabeshi, * Norio Itoh, * Tomoaki Yoshikawa & * Yasuo Tsutsumi * Laboratory of Biopharmaceutical Research, National Institute of Biomedical Innovation, 7-6-8, Saito-Asagi, Ibaraki, Osaka 567-0085, Japan * Kohei Yamashita, * Yasuo Yoshioka, * Kazuma Higashisaka, * Yuki Morishita, * Tokuyuki Yoshida, * Toshinobu Ogura, * Hiromi Nabeshi, * Kazuya Nagano, * Yasuhiro Abe, * Haruhiko Kamada, * Shin-ichi Tsunoda, * Tomoaki Yoshikawa & * Yasuo Tsutsumi * The Center for Advanced Medical Engineering and Informatics, Osaka University, 1-6, Yamadaoka, Suita, Osaka 565-0871, Japan * Yasuo Yoshioka, * Haruhiko Kamada, * Shin-ichi Tsunoda & * Yasuo Tsutsumi * Department of Developmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan * Kazuya Mimura, * Masatoshi Nozaki & * Itaru Yanagihara * Bioresources Research, Laboratory of Common Apparatus, National Institute of Biomedical Innovation, 7-6-8, Saito-Asagi, Ibaraki, Osaka 567-0085, Japan * Youko Monobe & * Takayoshi Imazawa * Vitamin C60 BioResearch Corporation, 1-3-19, Yaesu, Chuo-ku, Tokyo 103-0028, Japan * Hisae Aoshima * Mitsubishi Corporation, 2-6-1, Marunouchi, Chiyoda-ku, Tokyo 100-8086, Japan * Kiyoshi Shishido * Graduate School of Pharmaceutical Sciences, Kobe-Gakuin University, 1-1-3, Minatojima, Chuo-ku, Kobe, Hyogo 650-8586, Japan * Yuichi Kawai & * Tadanori Mayumi * Department of Biomedical Innovation, Graduate School of Pharmaceutical Sciences, Osaka University, 7-6-8 Saito-asagi, Ibaraki, Osaka 567-0085, Japan * Shin-ichi Tsunoda * Department of Obstetrics and Gynecology, University of Toyama, 2630, Sugitani, Toyama 930-0194, Japan * Shigeru Saito Contributions K.Y. and Y.Y. designed the study. K.Y., K.H., K.M., Y. Morishita, M.N., T. Yoshida, T.O., H.N., K.N., Y.A., H.K., Y. Monobe and T.I. performed the experiments. K.Y. and Y.Y. collected and analysed the data. K.Y. and Y.Y. wrote the manuscript. H.A., K.S., Y.K., T.M., S.T., N.I., I.Y., S.S. and T. Yoshikawa provided technical support and conceptual advice. Y.T. supervised the project. All authors discussed the results and commented on the manuscript. Competing financial interests The authors declare no competing financial interests. 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