Diese Arbeit wurde von der National Research Foundation of Korea (2013R1A1A1061387) und KU-KIST Forschungsfonds unterstützt.

1. Herstellung der Vorstufe <ol><li> Herstellung von Graphenoxid (GO): <ol><li> GO Vorbereitung mit modifizierten Hummer-Methode 14 <ol><li> Hinzufügen von 3,0 g Graphitflocken zu einer Mischung aus konzentrierter H 2 SO 4 / H 3 PO 4 (360: 40 ml) bei RT. (Hinweis: Besondere Sorgfalt muss bei der Verwendung von starken Säuren H 2 SO 4 und H 3 PO 4 entnommen werden.) </li><li> Hinzufügen KMnO 4 (18,0 g) langsam unter Rühren und Kühlen in einem Eisbad, um die Temperatur des Reaktionsgemisches auf &lt;35 ° C zu halten. (Die klebrig mit erhöhter Reaktionszeit-Lösung benötigen, um die ordnungsgemäße Methode verwenden, um ein effizientes Rühren aufrecht zu erhalten.) (Hinweis: Besondere Sorgfalt muss genommen werden, während es KMnO 4 aufgrund der exothermen Reaktion.) </li><li> Rühre 12 Stunden bei 50 ° C und dann auf RT abkühlen und gießt Reaktionsgemisch auf Eis (400 ml), das 30% H 2 O 2 (3 ml). </li><li> Filtern Sie die reAction Mischung unter Verwendung einer Metall US Standardtest Sieb (300 um), um nicht umgesetzte Graphit und Zentrifuge das Filtrat (4722 xg Geschwindigkeit für 2 Stunden) zu entfernen, um den Überstand zu entfernen. </li><li> Wiederholen Zentrifugationsschritt mit 200 ml Wasser, 200 ml 30% HCl, 200 ml Ethanol und destilliertem Wasser wieder bis zu einem pH von 5,0-6,0 zu erreichen Lösung bei. </li><li> Lyophilisieren die endgültigen Lösungen für einen flauschigen GO Pulver herzustellen. </li><li> Um Nano GO-Lösung herzustellen, in 40 ml dreifach destilliert Wasser (&gt; 18 M &amp; Omega;) aufzulösen 20 mg GO-Pulver und dann bei längerer Ultraschallbehandlung (35% Amplitude, 500 W, 2 h), Peeling, bis der gesamte Größenverteilung werden unter 150 nm, dann zentrifugieren es zweimal (10.625 xg Geschwindigkeit, 15 min), um Niederschläge zu (un-abgeblätterten großen GO Blätter) zu entfernen. </li></ol></li></ol></li><li> Vorbereitung plasmonischer Nanopartikel <ol><li> Herstellung von AuNPs <ol><li> Citrat-stabilisierten Kugelform Gold-Nanopartikel (AuNPs, OD = 1,0) von 30 nm Partikelgröße wurde für r-GO Reduktion verwendet. </li></ol></li><li> Herstellung von AuNRs 15 <ol><li> Vorbereitung der Keimlösung durch Zugabe einer frisch hergestellten 0,6 ml eiskalten Lösung von NaBH &amp; sub4; -Lösung (0,01 M) in eine wässrige Mischlösung compose von 0,25 ml HAuCl 4 (0,01 M) und 9,75 ml Cetyltrimethylammoniumbromid (CTAB, 0,1 M ). </li><li> Die resultierende Mischung kräftig für 0,5 min und dann halten Sie es bei 28 ° C für 3 Stunden. </li><li> Vorbereitung der Wachstumslösung durch Vermischen von 475 ml CTAB (0,1 M) wurden 3 ml AgNO 3 (0,01 M) und 20 ml HAuCl 4 (0,01 M). </li><li> Dann frisch hergestellten 3,2 ml Ascorbinsäure (0,01 M) zu der Mischung, gefolgt von der Zugabe von 0,8 ml einer wässrigen HCl (1,0 M) Lösung zuzugeben. </li><li> Im letzten Schritt hinzuzufügen 3,2 ml Keimlösung zu der Wachstumslösung bei 28 ° C und unterziehen das Reaktionsgemisch auf eine schnelle Inversion für ein paar Sekunden. Schließlich keep der resultierenden Mischung ungestört für mindestens 6 Stunden. </li><li> Analyse der hergestellten AuNRs mit UV-Vis-Spektroskopie zur Absorptionsmaxima (λ max) und TEM-Analyse (typischerweise die λ max und dem Seitenverhältnis wurde gefunden, 730 nm bzw. 3,5 sein). </li></ol></li><li> Herstellung von AuNSs 16 <ol><li> Vorbereitung einer wässrigen Stammlösung von 4- (2-Hydroxyethyl) -1-piperazinethansulfonsäure (HEPES) mit einer Konzentration von 100 mM und der pH auf 7,4 bei 25ºC einstellen durch Zugabe von 1,0 M NaOH-Lösung. </li><li> Mix 20 ml Phosphatpuffer (100 mM) mit 30 ml 2- [4- (2-Hydroxyethyl) -1-piperazinyl] ethansulfonsäure (100 mM). </li><li> Dann fügen Sie 500 ul von Gold (III) -chlorid-Trihydrat (20 mM) zu der obigen Mischung und hält bei 28,5 ° C für 30 min im Wasserbad. Lösung Farbe von hellgelb bis grünlich-blau nach 30 Minuten beobachtet werden. </li><li> Zentrifugieren Sie die Lösung bei 8928 xg Geschwindigkeit für 30 Minuten und zu dispergierendie Präzipitate in destilliertem Wasser. </li><li> Schließlich analysiert man die vorbereitete AuNSs mit UV-Vis-Spektroskopie zur Absorptionsmaxima (λ max) und TEM-Analyse für Teilchengröße Bestätigung ein, der 740 nm und 30 nm betragen. </li></ol></li></ol></li></ol> 2. Herstellung von r-GO mit sichtbarem Licht und AuNPs <ol><li> 1 ml plasmonic Nanopartikel (Abs 1,0 bei 520 nm für AuNPs, Abs 1,0 bei 750 nm für AuNRs und ABS-1,0 bei 730 nm für AuNSs bezeichnet), und 100 ul von Ammoniumhydroxid (28%, w / v%) und 10 ml der GO-Lösung (OD 1,0 bei 230 nm, 0,125 mg ml -1) in einem Pyrex-Glasreaktor mit einem Wasserzirkulationsmantel ausgestattet war. </li><li> Bestrahlen der Mischung mit Xe-Lampe (Leistungsdichte von 1,56 W cm -2) für 30 Minuten mit Wasserumlauf durch die Wasserzirkulationsmantel um die Temperatur auf 25 ° C zu halten und dann zu zentrifugieren die Lösung bei 10.625 xg Geschwindigkeit für 15 minentfernen Gold-Nanopartikeln. </li><li> Nehmen Sie den Überstand, der die vorbereitet r-GO, um mit UV-Vis-Spektralphotometer Analyse im Bereich von 200 bis 900 nm (r-GO sollte die Unterscheidungsabsorptionsbande bei 270 nm zeigen). </li></ol> 3. Ziel-DNA-Nachweis unter Verwendung von R-GO-Lösung 17 <ol><li> Für Fluoreszenzlöschung, fügen Sie 20 ul 10 -6 M Cy3-modifizierte ssDNA (5&#39;-ATC CTT ATC AAT ATT TAA CAA TAA TCC CTC-Cy3-3 &#39;) in GO oder r-GO Lösung, die 25 &amp; mgr; l GO (0,125 mg ml -1) oder r-GO (0,125 mg ml -1) in 1.955 &amp; mgr; l von 0,3 M PBS-Lösung (10 mM Phosphatpuffer, 0,3 M NaCl) und Inkubation für 10 min bei RT. </li><li> Messung der Fluoreszenzintensität der Proben mit Spektralfluorometer (λ ex = 529 nm). </li><li> Zur Zielerkennung, fügen Sie 200 ul der Target-Oligonukleotid-Lösung (5&#39;-GAG GGA TTA TTA TTG AAT ATT GAT AAG GAT-3 &#39;) in drei verschiedenen Konzentrationen (10 -6 &lt;/ sup&gt; M, 10 -7 M, 10 -8 M) in den GO oder r-GO-Lösung, enthaltend 20 ul 10 -6 M ssDNA-Cy3, 25 ul GO oder r-GO (0,125 mg ml -1) und 1755 &amp; mgr; l von 0,3 M PBS für die Fluoreszenz-Recovery-Experiment. 17 Hinweise: Lichtquellen &amp; Reactor Sichtbares Licht (400-780 nm) Quelle. Sichtbares Licht zu bestrahlen durch Pyrex-Glasreaktor (Fensterdurchmesser = 1,1 cm), die GO-Lösung mit Xe-Lampe (1,56 W / cm 2 Leistung). Die Photonenenergie an den Reaktor angelegt wird berechnet, um 4,8 × 10 21 Photonen pro min (2A-2C) sein. Nah-Infrarot (NIR) Laser. NIR-Laser (Fensterdurchmesser = 13,2 cm) mit Leistungsdichte von 0,36 W / cm 2, und die Betriebswellenlänge von 808 nm als Quelle für nahes Infrarotlicht für GO Reduktionsreaktionen (2E) verwendet wurde. Die Photonenenergie wird berechnet, um 2,43 × 10 21 Photonen pro min betragen. Reactor: Pyrex-Glasreaktor (Fensterdurchmesser = 1,1 cm; Reaktionsvolumen = 10 ml) mit einem Wasserumlauf Mantel ausgestattet ist sowohl für sichtbares Licht und NIR-Licht bestrahlt verwendet GO Reduktionsreaktionen (2F). </li></ol>

<ol>
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Wir haben nichts zu offenbaren.

Bestrahlung mit sichtbarem Licht auf GO Lösung für 30 min mit Gold-Nanopartikeln (AuNPs, AuNSs &amp; AuNRs) zeigte den schnellen Farbumschlag von hellgelb-braune bis schwarze Farbe (Abbildung 1). Um hochreines r-GO Produkt in hoher Ausbeute zu erhalten, gibt es zwei wichtige Faktoren zu folgen. Eine davon ist die Verwendung von AuNPs als effiziente plasmonic Katalysators, da AuNPs können stark das sichtbare Licht unter anderen Strukturen (dh AuNRs, AuNSs) absorbieren. Ein weiteres ist die Ve...

<html> Das erste entwickelte Scotch-Tape-basierte Methode 1 und chemische Gasphasenabscheidung 2 waren ausgezeichnet Methoden, um den ursprünglichen Zustand eines Graphen zu erzeugen, aber der Groß Graphen-Synthese oder Graphenschicht Bildung auf der Oberfläche mit großen Bereich haben als Schlüssel Begrenzung angesehen früheren Verfahren. 3 Eine mögliche Lösung für große R-GO Synthese naßchemischen synthetischen Verfahren, erfordert zunächst die Reaktionen mit starken Oxidationsmitteln, umfangreiche physikalische Behandlung wie Beschallung herzustellen GO Bogen und schließlich die Reduktion von Sauerstoff Funktionalitäten wie sein Hydroxy, Epoxid und Carbonylgruppen in GO ist wesentlich, um in seinen ursprünglichen physikalischen Eigenschaften zu gewinnen. 4 Teilweise wird die Reduktion von GO wurde entweder mit chemischen Verfahren unter Verwendung von Hydrazin oder seine Derivate 5 oder durch Wärmebehandlungsverfahren 550-1,100 ° durchgeführt ( C) in einer inerten oder reduzierenden Atmosphäre. 6 jove_content &quot;&gt; Diese Verfahren erfordern die giftigen Chemikalien, lange Reaktionszeit und hoher Temperatur, die Gesamtenergiebedarf für die r-GO Synthese erhöht. 7 Während die Foto-Bestrahlung Reduktionsverfahren, wie beispielsweise UV-induzierte, 8 photothermischen Verfahren unter Verwendung eines Xenon-Impuls Flash, 9 gepulsten Laser unterstützte 10 und photothermische Heizung mit Blitzlampen 11 sind auch für die Herstellung von gemeldet r-GO. Im Allgemeinen ist die geringe Effizienz der Umwandlung der photoinduzierten Verfahren auf die Verwendung von UV oder gepulste propagiert Laserbestrahlung, die hohe Photonenenergie liefern kann. Der geringe Energie von sichtbarem Licht Photonen schränkt seine Verwendung und nicht angezogen viel für r-GO-Synthese. Hervorragende Lichtabsorptionseigenschaften plasmonischer Nanopartikel im sichtbaren und / oder NIR-Bereich können die aktuellen Nachteile erheblich verbessern der Verwendung von sichtbarem Licht für r-GO-Synthese. 12,13 milden Reaktionsbedingungen kurze Reaktionszeit und begrenzter Verwendung toxischer chemicals könnte das sichtbare Licht induzierten Plasmonen-unterstützte photokatalytische Reduktion von GO als eine nützliche Alternative Methode zu machen. Im vorliegenden Verfahren beschreiben wir die effiziente und einfache r-GO Syntheseverfahren unter Verwendung von Plasmonen Nanopartikeln und sichtbares Licht. Der Reaktionsfortschritt wurde wie sphärische Gold-Nanopartikel (AuNPs), Gold-Nanostäbchen (AuNRs) und Gold nanostars (AuNSs) als stark abhängig von den Strukturen der Plasmonen Nanopartikel sein. Der Einsatz von AuNPs zeigten die wirksamste Verringerung der GO und die Nanopartikel leicht entfernbare und wiederverwertbare für den wiederholten Gebrauch (Abbildung 1). Die r-go mit sichtbarem Licht synthetisiert und AuNPs zeigten fast gleichen Qualität im Vergleich mit dem R-GO durch bekannte chemische Verfahren (Hydrazin), wie durch die Verwendung von verschiedenen analytischen Messungen und der Fluoreszenzlöschung / Recovery-basierte DNA-Nachweisverfahren nachgewiesen vorbereitet.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Cy3 modifeid ssDNA</td>
			<td>IDT(Iowa, USA)</td>
			<td></td>
			<td>HPLC purified by IDT</td>
		</tr>
		<tr>
			<td>Gold nanoparticles (30 nm)</td>
			<td>Ted Pella, Inc(Redding, CA, USA).</td>
			<td>15706-20</td>
			<td>colloidal solution</td>
		</tr>
		<tr>
			<td>4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid (HEPES) (99.5%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7365-45-9</td>
			<td></td>
		</tr>
		<tr>
			<td>Gold(III)Chloride Hydrate (99.999%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>&#160;27988-77-8</td>
			<td>strongly hygroscopic</td>
		</tr>
		<tr>
			<td>Sodium Borohydride (99.99%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>16940-66-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexadecyltrimethylammonium bromide (&#8805;99%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>57-09-0</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Ascorbic Acid(&#8805;99.0%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>50-81-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride (99.5%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver Nitrate&#160; (&#8805;99.0%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7761-88-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Graphite</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7782-42-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfuric acid</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7664-93-9</td>
			<td></td>
		</tr>
		<tr>
			<td>Phophoric acid</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7664-38-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium permanganate</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7722-64-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen peroxide</td>
			<td>JUNSEI</td>
			<td>23150-0350</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium hydroxide</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>1336-21-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Xe-lamp</td>
			<td>&#160;Cermax, Waltham, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NIR Laser</td>
			<td>Class-IV, Sanctity Laser, Shanghai, China&#160;</td>
			<td></td>
			<td>6W (output power)</td>
		</tr>
		<tr>
			<td>UV-Vis spectrophotometer&#160;</td>
			<td>S-3100, SINCO, South Korea</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission Electron Microscopy</td>
			<td>H-7650, Hitachi, Japan</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spectro Fluorometer</td>
			<td>Jasco FP-6500, Tokyo, Japan</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>X-ray Photoelectron Spectrometer</td>
			<td>AXIS&#8211;NOVA, KRATOS Inc., UK</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

visible-light induced reduction of graphene oxide using plasmonic nanoparticle

Vorliegende Arbeit zeigt die einfachen, chemischen kostenlos, schnell und energieeffiziente Methode, um reduzierte Graphenoxid (r-GO) Lösung bei RT produzieren mit Bestrahlung mit sichtbarem Licht mit Plasmonen Nanopartikel. Die Plasmonen Nanopartikel verwendet, um die Reduktionseffizienz von GO zu verbessern. Es dauert nur 30 min bei RT durch Beleuchten der Lösungen mit Xe-Lampe, kann der R-GO-Lösungen von Goldnanopartikeln vollständigen Entfernung durch einfache Zentrifugation Schritt erhalten werden. Die kugelförmigen Goldnanopartikel (AuNPs) im Vergleich zu den anderen Nanostrukturen ist die geeignetste plasmonic Nanostruktur für r-GO Zubereitung. Mit sichtbarem Licht die reduzierte Graphenoxid vorbereitet und AuNPs war ebenso qualitative als chemisch reduzierte Graphenoxid, die durch verschiedene analytische Verfahren, wie UV-Vis-Spektroskopie, Raman-Spektroskopie, Pulver-XRD und XPS unterstützt wurde. Die reduzierte Graphenoxid mit sichtbarem Licht bereit zeigt hervorragende Löscheigenschaften über die Fluorzier Moleküle auf ssDNA und ausgezeichnete Fluoreszenz Recovery für Ziel-DNA-Detektion modifiziert. Die r-GO durch Recycling AuNPs hergestellt wird festgestellt, dass der gleiche Qualität mit der des chemisch reduziert r-GO können. Die Verwendung von sichtbarem Licht mit plasmonic Nanopartikel zeigt die gute Alternative Verfahren zur r-GO-Synthese.

Abbildung 1 zeigt die Gesamtschema für sichtbares Licht und Plasmonen-Nanopartikel auf der Basis r-GO Reduktionsreaktion. Abbildung 2 zeigt die instrumental-Setup für die Reaktionen. Nach der Reaktion ist es erforderlich, den Zentrifugationsschritt, um das verwendete Photokatalysator (AuNSs, AuNRs oder AuNPs), wie in 3A gezeigt, zu entfernen. Die HRTEM-Analyse zeigt das vollständige Entfernen von Nanopartikeln in dem Überstand (r-GO) (3B), die auch ...

Watch this Scientific Journal Video about Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle at JoVE.com

Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Ein einfaches Protokoll zur Herstellung von reduzierten Graphenoxids Verwendung von sichtbarem Licht und plasmonic Nanopartikel beschrieben.

Sichtbares Licht induzierte Reduktion von Graphenoxid Mit Plasmonische Nanopartikel

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using ...

visible-light-induced-reduction-graphene-oxide-using-plasmonic

Research

JoVE Journal

Engineering

14.3K Aufrufe.  Korea University.  Ein einfaches Protokoll zur Herstellung von reduzierten Graphenoxids Verwendung von sichtbarem Licht und plasmonic Nanopartikel beschrieben. 

Serie: Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on photoconduction, which has been one of the most commonly used techniques for terahertz generation 1-8. Terahertz generation in a photoconductive emitter is achieved by pumping an ultrafast photoconductor with a pulsed or heterodyned laser illumination. The induced photocurrent, which follows the envelope of the pump laser, is routed to a terahertz radiating antenna connected to the photoconductor contact electrodes to generate terahertz radiation. Although the quantum efficiency of a photoconductive emitter can theoretically reach 100%, the relatively long transport path lengths of photo-generated carriers to the contact electrodes of conventional photoconductors have severely limited their quantum efficiency. Additionally, the carrier screening effect and thermal breakdown strictly limit the maximum output power of conventional photoconductive terahertz sources. To address the quantum efficiency limitations of conventional photoconductive terahertz emitters, we have developed a new photoconductive emitter concept which incorporates a plasmonic contact electrode configuration to offer high quantum-efficiency and ultrafast operation simultaneously. By using nano-scale plasmonic contact electrodes, we significantly reduce the average photo-generated carrier transport path to photoconductor contact electrodes compared to conventional photoconductors 9. Our method also allows increasing photoconductor active area without a considerable increase in the capacitive loading to the antenna, boosting the maximum terahertz radiation power by preventing the carrier screening effect and thermal breakdown at high optical pump powers. By incorporating plasmonic contact electrodes, we demonstrate enhancing the optical-to-terahertz power conversion efficiency of a conventional photoconductive terahertz emitter by a factor of 50 10.

We describe methods for the design, fabrication, and experimental characterization of plasmonic photoconductive emitters, which offer two orders of magnitude higher terahertz power levels compared to conventional photoconductive emitters.

Konstruktion, Fertigung und experimentelle Charakterisierung Plasmonic Photoconductive Terahertz-Emitter

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Forschung

Ingenieurwesen

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends with respect to predefined landmarks are precisely located using standard optical transmission microscopy before encapsulation in an electron-sensitive resist. Trenches representing the electrode layout are subsequently designed by electron-beam lithography. Metal electrodes are then fabricated by thermally evaporating a Cr/Au layer followed by a chemical lift-off. The contacted silver nanowires are finally transferred to a leakage radiation microscope for surface plasmon excitation and characterization8,9. Surface plasmons are launched in the nanowires by focusing a near infrared laser beam on a diffraction-limited spot overlapping one nanowire extremity5,9. For sufficiently large nanowires, the surface plasmon mode leaks into the glass substrate9,10. This leakage radiation is readily detected, imaged, and analyzed in the different conjugate planes in leakage radiation microscopy9,11. The electrical terminals do not affect the plasmon propagation. However, a current-induced morphological deterioration of the nanowire drastically degrades the flow of surface plasmons. The combination of surface plasmon leakage radiation microscopy with a simultaneous analysis of the nanowire electrical transport characteristics reveals the intrinsic limitations of such plasmonic circuitry.

Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 &#181;m x&#160;0.7 cm x&#160;2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 &#956;m diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 &#956;m polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete.

A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 &#956;m micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

Entwicklung eines 3D-Graphen-Elektroden-Dielektrophoretische Geräte

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The ...

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

Schreiben und Niedertemperatur-Charakterisierung von Nanostrukturen

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

Synthese und Funktionalisierung von 3D-Graphen-Nano Materialien: Graphene Aerogele und Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

Die Messung der Streunichtlinearitäten von einem Einzel Plasmonische Nanopartikel

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (&#181;PAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

The study demonstrates the growth of iridium oxide-reduced graphene oxide (IrO2-RGO) nanohybrid thin films on irregular and rough screen-printed carbon substrate through a green electrochemical synthesis, and their implementation as a pH sensor with a patterned paper-fluidic platform.

Iridium-Oxid-reduziertem Graphenoxid Nanohybrid- Thin Film Modified Siebdruck Elektroden als Einweg-Elektro Papier Mikrofluidik pH-Sensoren

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use ...

Preparation of ZnO Nanorod/Graphene/ZnO Nanorod Epitaxial Double Heterostructure for Piezoelectrical Nanogenerator by Using Preheating Hydrothermal

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we describe a one-step fabrication technique to synthesis freestanding ZnO nanorod/graphene/ZnO nanorod double heterostructure. The preparation of the double heterostructure is performed by using thermal chemical vapor deposition (CVD) and preheating hydrothermal technique. In addition, the morphological properties were characterized by using the scanning electron microscopy (SEM). The utility of freestanding double heterostructure is demonstrated by fabricating the piezoelectric nanogenerator. The electrical output is improved up to 200% compared to that of a single heterostructure owing to the coupling effect of the piezoelectricity between the arrays of ZnO nanorods on the top and bottom of graphene. This unique double heterostructure have a tremendous potential for applications of electrical and optoelectrical devices where the high number density and specific surface area of nanorod are needed, such as pressure sensor, immuno-biosensor and dye-sensitized solar cells.

One-step fabrication method for obtaining freestanding epitaxial double heterostructure is presented. This approach could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure, leading to a piezoelectric nanogenerator with an increased output electrical performance.

Herstellung von ZnO-Nanostäbchen / Graphene / ZnO-Nanostäbchen Epitaxial Doppelheterostruktur für Piezoelektrische Nanogenerator mithilfe Vorwärmen Hydrothermale

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we ...

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

We describe the synthesis and properties of multifunctional Fe2O3-Au nanoparticles produced by a wet chemical approach and investigate their photothermal properties using laser irradiation. The composite Fe2O3-Au nanoparticles retain the properties of both materials, creating a multifunctional structure with excellent magnetic and plasmonic properties.

Multifunktions-Hybrid Fe<sub&gt; 2</sub&gt; O<sub&gt; 3</sub&gt; -Au Nanopartikel für effiziente Plasmonische Heizung

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.