Diese Arbeit wird als Teil des Zentrums für Atomic Level-Catalyst-Design-, Energy Frontier Research Center des US Department of Energy, Office of Science, Office of Basic Energy Sciences unter Preis Nummer DE-SC0001058 unterstützt und finanziert auch von Vorstand unterstützt Regents unter Zuschüsse Verleihungsnummer LEQSF (2009-14)-EFRC-MATCH und LEDSF-EPS (2012)-OPT-IN-15. MRCAT Operationen werden von der Abteilung Energie-und den MRCAT Mitgliedsinstitutionen unterstützt. Die Verwendung der Advanced Photon Source in ANL wird durch das US Department of Energy, Office of Science, Office of Basic Energy Sciences, unter Vertrag Nr. DE-AC02-06CH11357 unterstützt. Finanzielle Unterstützung für JTM wurde als Teil des Instituts für Atom-effiziente chemische Transformationen (IACT), einem Energy Frontier Research Center des US Department of Energy, Office of Science, Office of Basic Energy Sciences zur Verfügung gestellt.

Millifluidics Set-up: Kaufen Sie einen millifluidic Chip (von Polyesterterephthalat Polymer) aus Microplumbers Microsciences LLC, die Serpentinen-Kanäle mit Abmessungen von 2 mm (W) x 0,15 mm (H) x 220 mm (L). Verwenden FEP-Schlauch mit den Abmessungen von 0,25 mm ID, 1/16 in OD, zum Verbinden des Chips mit der Pumpe. Zwei unterschiedliche Pumpen für die zwei verschiedenen Experimenten. Verwendung P-Pumpe für das erste Experiment (Kupfer-Nanopartikel) und dem millifluidic Einrichtung für das zweite Experiment (Goldnanopartikel). Um das Problem der Gasblasen in den Kanälen zu minimieren, frisch zubereitete NaBH 4-Lösung wurde offen gelassen, um für ~ 10-15 min stehen vor dem Pumpen in den Chip, so dass die Gasblasen aus der Lösung entweichen. Dieser Schritt wurde für unsere Experimente folgten. 1. Synthese von Ultra-kleine Kupfer-Nano-Clustern (UCNCs) <ol><li> Chemikalien benötigt: Erhalten Kupfer (II) nitrate Hydrat, Natriumborhydrid, Natriumhydroxid-Pellets und O-[2 - (3-mercaptopropionylamino) ethyl]-O&#39;-Methylpolyethylenglykol (MW = 5.000) [MPEG] und sämtliche Chemikalien ohne weitere Reinigung. Verwenden Nanopure-Wasser (18,2 MOhm-cm) für das Experiment. </li><li> Mit P-Pumpe unter Stickstoffdruck für das Experiment geregelt. Testen der Pumpen mit Wasser als Lösungsmittel bei unterschiedlichen Drücken vor dem Experiment mit den entsprechenden Strömungsraten (ml / h) zu korrelieren. Spülen des Reaktors und Rohr millifluidic mit entionisiertem Wasser vor dem Beginn des Experiments. </li><li> Lösen Sie 174 mg (0,95 mmol) Kupfer (II)-Nitrat und 610 mg (0.122 mmol) O-[2 - (3-mercaptopropionylamino) ethyl]-O&#39;-Methylpolyethylenglykol in 28 ml Nanopure-Wasser und halten sie in eine Ampulle mit einem Eingangskanal verbunden werden </li><li> Halten Sie eine andere Lösung von 111 mg (2,93 mmol) Natriumborhydrid und 102 mg (2,78 mmol) Natriumhydroxid in 28 ml (pH ~ 13) in einem anderen Fläschchen und verbinden Sie es mit demanderen Eingangskanal. </li><li> Fluss beide Lösungen gleichzeitig in der millifluidic Reaktor bei unterschiedlichen Flussraten (siehe unten) und sammeln die resultierende UCNCs am Ausgang in Glasfläschchen. Spülen Sie die Lösung mit Stickstoff und speichern Sie es unter Stickstoff. </li><li> Arbeiten die Pumpen unter verschiedenen konstanten Drücken von 50 mbar (6,81 ml / h), 100 mbar (14.31 ml / h), 200 mbar (32,7 ml / h) und 300 mbar (51,4 ml / h) bei Raumtemperatur für die Synthese von UCNCs bei unterschiedlichen Strömungsgeschwindigkeiten. </li></ol> Während der Synthese wurde unter Verwendung der millifluidic Anordnung mit P-Pumpe gezeigt, es kann auch mit dem Handgerät von millifluidic Millifluidica geführt werden. 2. Zeitaufgelöste In-situ-Kinetische Untersuchungen an Gold-Nanopartikel-Formation <ol><li> Chemikalien benötigt: Erhalten Chlorwasserstoffsäure (HAuCl4 3H 2 O.) Meso-2 ,3-Dimercaptobernsteinsäure (DMSA) und Natriumborhydrid &amp; #160, und nutzen Sie alle Chemikalien ohne weitere Reinigung. Verwenden Nanopure-Wasser (18,2 MOhm-cm) für das Experiment. </li><li> Verwenden Sie hohe Präzision, voll automatisiert, pulsationsfreier Spritzenpumpen, um die Flüssigkeiten innerhalb des Chips fließen. Testen Sie die Pumpen mit Wasser als Lösungsmittel bei unterschiedlichen Flussraten vor dem Versuch, die erforderliche Durchflussrate zu optimieren. </li><li> Standardlösungen von (i) HAuCl 4. 3H 2 O (10 mmol, 118,2 mg/30 ml) und (ii) DMSA (20 mmol, 109,2 mg/30 ml) mit 50 mg Natriumhydroxid (pH 12) in nanoreinem Wasser. </li><li> Führen Sie die beiden Lösungen durch zwei separate Spritzen in die millifluidic Chip mit einer konstanten Flussrate von 10 ml / h über das automatische Pumpe. </li><li> Paar der millifluidic Chip an den Synchrotron-Strahllinie mit einem Metall-Bühne, die den Zugang zu Bewegung in XYZ-Richtung hat und sammeln die XAS Daten auf verschiedenen Zonen auf dem Chip als die Lösungen durch den Chip gepumpt. </li></ol> Während die &lt;em&gt; in-situ-Analyse wurde unter Verwendung der millifluidic Anordnung mit P-Pumpe gezeigt ist, kann auch mit einem Hand millifluidic Vorrichtung durchgeführt werden. 3. Continuous Flow Gold-Katalyse Dieses Verfahren wurde unter Verwendung eines Hand-millifluidic Vorrichtung gezeigt. <ol><li> Chemikalien benötigt: Erhalten Chlorwasserstoffsäure (HAuCl4 3H 2 O.), Meso-2 ,3-Dimercaptobernsteinsäure (DMSA), Natriumborhydrid, 4-Nitrophenol, 4-Aminophenol und nutzen Sie alle Chemikalien ohne weitere Reinigung. Verwenden Nanopure-Wasser (18,2 MOhm-cm) für das Experiment. </li><li> Katalysator-Herstellung:. Bereiten Standardlösungen von HAuCl4 3H 2 O (10 mmol, 118,2 mg/30 ml), DMSA (20 mmol, 109,2 mg/30 ml) und NaBH 4 (10 mmol, 11,34 mg/30 ml) in Nanopure Wasser. </li><li> Nehmen Sie je 10 ml HAuCl4 DMSA und Lösungen in zwei Fläschchen und fließen them innerhalb des Chips mit dem Hand millifluidic Vorrichtung mit einer gleichförmigen Fließgeschwindigkeit von 12 ml / h für 45 min. </li><li> Fluss 10 mmol NaBH 4 innerhalb des Chips bei 12 ml / h Durchflussmenge für 15 min, um die Au (I) zu reduzieren Au (0). </li><li> Schließlich, waschen Sie die Chips mit Nanopure-Wasser für 30 min bei der gleichen Flussrate vor Durchführung der Katalyseexperimente. </li><li> Katalysereaktion: Durchführen der chemischen Umwandlungsreaktion (Reduktion) von 4-Nitrophenol (NP-4) in 4-Aminophenol (4-AP) in der Gold-Katalysator (oben hergestellt) beschichtet millifluidic Kanal wie unten angegeben. </li><li> 15 ml der 9 x 10 -5 mol Lösung von 4-NP mit 3,3 ml 0,65 mol NaBH 4-Lösung von 4-Nitrophenolat-Ionen-(4-NPI) bilden. </li><li> Passieren die resultierende Lösung über die Gold-Katalysator im Chip bei einer konstanten Fließgeschwindigkeit von 5 ml / h, um die katalytische Aktivität zu bewerten abgeschieden. Analyse des UV-Vis-Spektren der gesammelten Produkte im Wellenlängenbereich von 250-500 nm die Umwandlung von 4-NP bestätigen. </li><li> Abschätzung der katalytischen Aktivität der Reaktion durch den Erhalt der Kalibrierungskurve von 4-NPI. Kalibrierungskurve durch Auftragen der experimentell beobachteten Absorptionsintensität (I) von 4-NPI auf verschiedenen Standardkonzentrationen gewonnen werden. Die Peakhöhen (bei ​​399 nm) für die UV-Vis-Absorptions-Kurven stellen die Absorption Intensitätswerte (I) und nach der Bier-Lambert Gesetz, würde jede Änderung in der Spitzenhöhenwert entsprechende Änderung in seiner Konzentration zu zeigen. Daher schätzen die katalytische Aktivität durch Differenz in Anfangs-und Endkonzentrationen der Reaktionspartner aus der Eichkurve. Wenn beispielsweise die Peakhöhe ist 1 Einheit (Fig. 6) entspricht einer katalytischen Umwandlung von 90% (bezogen auf die Eichkurve). </li></ol>

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Technol. 32, 1799-1805 (2009).</li><li>Abahmane, L., Knauer, A., K&#246;hler, J. M., Gro&#223;, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+polypyridine+derivatives+using+alumina+supported+gold+nanoparticles+under+micro+continuous+flow+conditions.">Synthesis of polypyridine derivatives using alumina supported gold nanoparticles under micro continuous flow conditions.</a> Chem. Eng. J. 167, 519-526 (2011).</li><li>Negishi, Y., Tsukuda, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-Pot+Preparation+of+Subnanometer-Sized+Gold+Clusters+via+Reduction+and+Stabilization+by+meso-2,3-Dimercaptosuccinic+Acid.">One-Pot Preparation of Subnanometer-Sized Gold Clusters via Reduction and Stabilization by meso-2,3-Dimercaptosuccinic Acid.</a> J. Am. Chem. 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J. 16, 4999-5003 (2010).</li><li>Kuroda, K., Ishida, T., Haruta, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+4-nitrophenol+to+4-aminophenol+over+Au+nanoparticles+deposited+on+PMMA.">Reduction of 4-nitrophenol to 4-aminophenol over Au nanoparticles deposited on PMMA.</a> J. Mol. Catal. A Chem. 298, 7-11 (2009).</li><li>Navin, C. V., Krishna, K. S., Theegala, C. S., Kumar, C. S. S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lab-on-a-chip+devices+for+gold+nanoparticle+synthesis+and+their+role+as+a+catalyst+support+for+continuous+flow+catalysis.">Lab-on-a-chip devices for gold nanoparticle synthesis and their role as a catalyst support for continuous flow catalysis.</a> Nanotech. 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Alle Autoren außer CSSR Kumar erklären, dass sie keine finanziellen Interessen konkurrieren. C. SSR Kumar ist der Gründer der Firma Millifluidica LLC.

-O-Methylpolyethylenglykol (MW = 5.000) [MPEG] - UCNCs die durch die Reduktionsreaktion von Kupfernitrat mit Natriumborhydrid in Gegenwart von polymeren Verkappungsmittel O-[(3-Mercaptopropionylamino) ethyl-2] gebildet wird. Die Reaktion wurde in der millifluidic Chip-Reaktor bei unterschiedlichen Flussraten, wie 6,8 ml / h, 14,3 ml / h, 32,7 ml / h und 51,4 ml / h, um die Wirkung von Flussraten auf die gebildeten UCNCs studieren durchgeführt. Die jeweiligen Verweilzeiten für die oben genannten Durchflussraten sind 47...

Lab-on-a-Chip (LOC)-Geräte für die chemische Synthese haben signifikanten Vorteil in Bezug auf die erhöhte Masse-und Wärmetransport, überlegene Reaktionskontrolle, hoher Durchsatz und sicherere Arbeitsumgebung 1 demonstriert. Diese Geräte lassen sich grob in Fluidik-Chip basiert und nonchip Fluidikvorrichtungen klassifiziert werden. Unter den Chip-basierte Fluidik, ist gut untersucht und Mikrofluidik ein Thema in der Literatur 2-5 gut abgedeckt. Nonchip basierend LOC-Systeme verwenden Rohrreaktoren 6. Üblicherweise werden mikrofluidische Systeme für präzise Kontrolle und Manipulation von Flüssigkeiten, die geometrisch Submillimeter-Skala eingeschränkt verwendet werden. Wir haben vor kurzem wurde das Konzept der Chip-basierten millifluidics, die für die Manipulation von Flüssigkeiten in Kanälen im Millimeterbereich verwendet werden kann (entweder Breite oder Tiefe oder beide der Kanäle mindestens einen Millimeter groß) 7-9. Darüber hinaus sind die Chips millifluidic relativ leicht herzustellen welle, die ähnliche Kontrolle über die Durchflussraten und Manipulation von Reagenzien. Diese Chips könnten auch bei höheren Flussraten betrieben werden, die Schaffung kleiner Aufenthaltszeiten, damit, mit der Möglichkeit für Scale-up der kontrollierten Synthese von Nanopartikeln mit enger Größenverteilung. Als Beispiel haben wir kürzlich gezeigt, die Synthese von ultrakleinen Kupfernanocluster und dadurch mit ihnen in situ Röntgenabsorptionsspektroskopie sowie TEM. Fähigkeit, kleine Verweilzeiten innerhalb millifluidic Kanäle in Verbindung mit der Verwendung von MPEG, die sehr effizient zweizähnigen PEGylierten Stabilisierungsmittel für die Bildung von stabilen Kolloiden Kupfernanocluster 7 erhalten. Neben der Synthese von Chemikalien und Nanomaterialien könnten die millifluidics bieten, auf höhere Volumen und die Konzentration an der Sondenbereich, eine Plattform, die synthetische verallgemeinerte und effizient für die zeitaufgelöste kinetische Studien und Ebenfalls möglich istves besseres Signal-Rausch-Verhältnis als mikrofluidische Systeme 7,10. Wir zeigen die Verwendung von millifluidic Chip als Beispiel für die zeitaufgelöste Analyse des Wachstums von Gold-Nanostrukturen aus der Lösung unter Verwendung von in situ XAS mit einer Zeitauflösung so klein wie 5 ms 11. Auch die Mehrheit der Mikroreaktoren bisher für die Katalyse-Anwendungen entwickelt werden, basierend auf Silizium 12,13. Ihre teure Herstellung neben geringen Mengen erzeugt macht sie für große Fertigungs ungeeignet. Die zwei allgemeine Verfahren für die Beschichtung der Kanäle mit Nanokatalysatoren - chemische und physikalische, die oft als Silizium-Beschichtungsverfahren bezeichnet werden, sind derzeit in der Mode 14,15. Zusätzlich zu teuren Mikroherstellung, ein Verstopfen der Kanäle macht Mikroreaktor Katalyse für Großserienfertigung ungeeignet. Obwohl Mikroreaktoren für die heterogene Katalyse in der Mikro kontinuierlichen Durchflussverfahren earli verwendeter 16-18, die Fähigkeit, die Richtung zu steuern, und die Morphologie der eingebettete nanostrukturierte Goldkatalysatoren im kontinuierlichen Strömungskanäle wurde nie erforscht. Wir haben kürzlich eine Technik zur Beschichtung der millifluidic Kanäle mit Au-Katalysatoren, mit Nanoabmessungen und Morphologie (Fig. 5) 11 gesteuert wird, zur Durchführung der Katalyse industriell wichtiger chemischer Reaktionen. Als Beispiel haben wir Umwandlung von 4-Nitrophenol in 4-Aminophenol durch die nanostrukturierte Gold innerhalb der Kanäle beschichtet millifluidic katalysierte gezeigt. Bedenkt man, dass ein einzelner Reaktor millifluidic Chip Flussraten von 50-60 ml / h, 7 Hochdurchsatz und kontrollierte Synthese von Chemikalien produzieren, ist entweder durch kontinuierlichen Betrieb oder die parallele Verarbeitung möglich. Um über die Möglichkeiten die millifluidics bieten, mit wie oben beschrieben, einige Beispiele zu nutzen, wir zeigen auch, eine benutzerfreundlichemillifluidic Gerät, das portabel ist und hat die alle erforderlichen Komponenten wie Chips millifluidic, Verteiler, Stromregler, Pumpen und elektrischen Verbindungen integriert. Eine solche millifluidic Gerät, wie in der 7 gezeigt, ist jetzt von der Firma Millifluidica LLC ( <a href="http://www.millifluidica.com" target="_blank">www.millifluidica.com</a> ). Das Manuskript ist auch Protokolle mit dem Hand millifluidic Vorrichtung, wie unten beschrieben, für die kontrollierte Synthese von Nanomaterialien, zeitaufgelöste Analyse von Reaktionsmechanismen und kontinuierlichen Katalyse.

<table border="1">
	<tbody>
		<tr>
			<td>Copper (II) nitrate hydrate</td>
			<td>Sigma-Aldrich</td>
			<td>13778-31-9</td>
			<td>99.999% pure</td>
		</tr>
		<tr>
			<td>O-[2-(3-mercaptopropionylamino)ethyl]-O&#8242;-methylpolyethylene glycol</td>
			<td>Sigma-Aldrich</td>
			<td>401916-61-8&#160;</td>
			<td>MW=5,000</td>
		</tr>
		<tr>
			<td>HAuCl4.3H2O (Chloroauric acid)</td>
			<td>Sigma-Aldrich</td>
			<td>27988-77-8&#160;</td>
			<td>99.999% pure</td>
		</tr>
		<tr>
			<td>meso-2,3-dimercaptosuccinic acid (DMSA)</td>
			<td>Sigma-Aldrich</td>
			<td>304-55-2</td>
			<td>~98% pure</td>
		</tr>
		<tr>
			<td>4-Nitrophenol</td>
			<td>Sigma-Aldrich</td>
			<td>100-02-7&#160;</td>
			<td>spectrophotometric grade</td>
		</tr>
		<tr>
			<td>4-Aminophenol</td>
			<td>Sigma-Aldrich</td>
			<td>123-30-8&#160;</td>
			<td>&#62;99% pure (HPLC grade)</td>
		</tr>
		<tr>
			<td>Sodium borohydride</td>
			<td>Sigma-Aldrich</td>
			<td>16940-66-2&#160;</td>
			<td>98% pure</td>
		</tr>
		<tr>
			<td>Sodium hydroxide pellets</td>
			<td>Sigma-Aldrich</td>
			<td>1310-73-2&#160;</td>
			<td>99.99% pure</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>[header]</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>EQUIPMENT</td>
		</tr>
		<tr>
			<td>Millifluidic Chips</td>
			<td>Microplumbers Microsciences LLC</td>
			<td>SDC-01</td>
			<td>Made from polyester terephthalate polymer</td>
		</tr>
		<tr>
			<td>Pressure Pump</td>
			<td>Mitos P-Pump, Dolomite</td>
			<td>3200016</td>
			<td></td>
		</tr>
		<tr>
			<td>Automated Syringe Pump</td>
			<td>Cetoni Automation and Microsystems, GmbH</td>
			<td></td>
			<td>Syringe pump neMESYS</td>
		</tr>
		<tr>
			<td>UV-3600 UV-VIS-NIR Spectrophotometer</td>
			<td>Shimadzu</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hand-held Millifluidic Device</td>
			<td>Millifluidica</td>
			<td>SCMD-1008</td>
			<td>Figure 7</td>
		</tr>
	</tbody>
</table>

millifluidics for chemical synthesis and time-resolved mechanistic studies

Verfahren unter Verwendung millifluidic Vorrichtungen für die chemische Synthese und zeitaufgelöste mechanistische Studien, indem drei Beispielen beschrieben. In der ersten wird die Synthese von ultrakleinen Kupfernanocluster beschrieben. Das zweite Beispiel stellt ihre Nützlichkeit für die Untersuchung der zeitaufgelösten Kinetik von chemischen Reaktionen durch Analyse unter Verwendung von Gold-Nanopartikel-Bildung in situ Röntgenabsorptionsspektroskopie. Das letzte Beispiel zeigt, kontinuierlichen Fluss Katalyse von Reaktionen innerhalb millifluidic Kanal mit nanostrukturierten Katalysator beschichtet.

Nun verteilt und gleichmäßig große Kupfer-Nanocluster mit einer engen Größenverteilung wurden mit dem millifluidic Chip-Setup (Abb. 1a) erhalten. Die unterschiedlichen Strömungsgeschwindigkeiten für die Synthese verwendet hatte keine signifikante Wirkung auf die Größe der Cluster. Dennoch, mit Zunahme der Strömungsrate, gibt es eine beobachtbare Verbesserung der Verengung der Grßenverteilung. UCNCs mit einem besten engen Größenverteilung wurden bei einer Fließgeschwindigkeit von 32,7 ml / h erhalten. Die G...

Watch this Scientific Journal Video about Millifluidics for Chemical Synthesis and Time-resolved Mechanistic Studies at JoVE.com

Millifluidics for Chemical Synthesis and Time-resolved Mechanistic Studies

Millifluidic Geräte sind für die kontrollierte Synthese von Nanomaterialien, zeitaufgelösten Analyse von Reaktionsmechanismen und kontinuierlichen Katalyse eingesetzt.

Millifluidics für Chemische Synthese und Zeitaufgelöste mechanistische Studien

Procedures utilizing millifluidic devices for chemical synthesis and time-resolved mechanistic studies are described by taking three examples. In the ...

millifluidics-for-chemical-synthesis-time-resolved-mechanistic

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11.1K Aufrufe.  Louisiana State University.  Millifluidic Geräte sind für die kontrollierte Synthese von Nanomaterialien, zeitaufgelösten Analyse von Reaktionsmechanismen und kontinuierlichen Katalyse eingesetzt. 

Serie: Millifluidics for Chemical Synthesis and Time-resolved Mechanistic Studies

Combinatorial Synthesis of and High-throughput Protein Release from Polymer Film and Nanoparticle Libraries

Polyanhydrides are a class of biomaterials with excellent biocompatibility and drug delivery capabilities. While they have been studied extensively with conventional one-sample-at-a-time synthesis techniques, a more recent high-throughput approach has been developed enabling the synthesis and testing of large libraries of polyanhydrides1. This will facilitate more efficient optimization and design process of these biomaterials for drug and vaccine delivery applications. The method in this work describes the combinatorial synthesis of biodegradable polyanhydride film and nanoparticle libraries and the high-throughput detection of protein release from these libraries. In this robotically operated method (Figure 1), linear actuators and syringe pumps are controlled by LabVIEW, which enables a hands-free automated protocol, eliminating user error. Furthermore, this method enables the rapid fabrication of micro-scale polymer libraries, reducing the batch size while resulting in the creation of multivariant polymer systems. This combinatorial approach to polymer synthesis facilitates the synthesis of up to 15 different polymers in an equivalent amount of time it would take to synthesize one polymer conventionally. In addition, the combinatorial polymer library can be fabricated into blank or protein-loaded geometries including films or nanoparticles upon dissolution of the polymer library in a solvent and precipitation into a non-solvent (for nanoparticles) or by vacuum drying (for films). Upon loading a fluorochrome-conjugated protein into the polymer libraries, protein release kinetics can be assessed at high-throughput using a fluorescence-based detection method (Figures 2 and 3) as described previously1. This combinatorial platform has been validated with conventional methods2 and the polyanhydride film and nanoparticle libraries have been characterized with 1H NMR and FTIR. The libraries have been screened for protein release kinetics, stability and antigenicity; in vitro cellular toxicity, cytokine production, surface marker expression, adhesion, proliferation and differentiation; and in vivo biodistribution and mucoadhesion1-11. The combinatorial method developed herein enables high-throughput polymer synthesis and fabrication of protein-loaded nanoparticle and film libraries, which can, in turn, be screened in vitro and in vivo for optimization of biomaterial performance.

This method describes the combinatorial synthesis of biodegradable polyanhydride film and nanoparticle libraries and the high-throughput detection of protein release from these libraries.

Kombinatorische Synthese von und High-Throughput-Protein Release von Polymer Film-und Nanopartikel-Bibliotheken

Polyanhydrides are a class of biomaterials with excellent biocompatibility and drug delivery capabilities. While they have been studied extensively with ...

Forschung

Biotechnik

High-throughput Synthesis of Carbohydrates and Functionalization of Polyanhydride Nanoparticles

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design efficacious vaccines carriers. Nanoparticle-based platforms can prolong the persistence of vaccine antigens, which could improve vaccine immunogenicity1. Several biodegradable polymers have been studied as vaccine delivery vehicles1; in particular, polyanhydride particles have demonstrated the ability to provide sustained release of stable protein antigens and to activate antigen presenting cells and modulate immune responses2-12.
The molecular design of these vaccine carriers needs to integrate the rational selection of polymer properties as well as the incorporation of appropriate targeting agents. High throughput automated fabrication of targeting ligands and functionalized particles is a powerful tool that will enhance the ability to study a wide range of properties and will lead to the design of reproducible vaccine delivery devices.
The addition of targeting ligands capable of being recognized by specific receptors on immune cells has been shown to modulate and tailor immune responses10,11,13 C-type lectin receptors (CLRs) are pattern recognition receptors (PRRs) that recognize carbohydrates present on the surface of pathogens. The stimulation of immune cells via CLRs allows for enhanced internalization of antigen and subsequent presentation for further T cell activation14,15. Therefore, carbohydrate molecules play an important role in the study of immune responses; however, the use of these biomolecules often suffers from the lack of availability of structurally well-defined and pure carbohydrates. An automation platform based on iterative solution-phase reactions can enable rapid and controlled synthesis of these synthetically challenging molecules using significantly lower building block quantities than traditional solid-phase methods16,17.
Herein we report a protocol for the automated solution-phase synthesis of oligosaccharides such as mannose-based targeting ligands with fluorous solid-phase extraction for intermediate purification. After development of automated methods to make the carbohydrate-based targeting agent, we describe methods for their attachment on the surface of polyanhydride nanoparticles employing an automated robotic set up operated by LabVIEW as previously described10. Surface functionalization with carbohydrates has shown efficacy in targeting CLRs10,11 and increasing the throughput of the fabrication method to unearth the complexities associated with a multi-parametric system will be of great value (Figure 1a).

In this article, a high throughput method is presented for the synthesis of oligosaccharides and their attachment to the surface of polyanhydride nanoparticles for further use in targeting specific receptors on antigen presenting cells.

Hochdurchsatz-Synthese von Kohlenhydraten und Funktionalisierung von Nanopartikeln Polyanhydrid

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design ...

Microfabrication of Nanoporous Gold Patterns for Cell-material Interaction Studies

Nanostructured materials with feature sizes in tens of nanometers have enhanced the performance of several technologies, including fuel cells, biosensors, biomedical device coatings, and drug delivery tools. Nanoporous gold (np-Au), produced by a nano-scale self-assembly process, is a relatively new material that exhibits large effective surface area, high electrical conductivity, and catalytic activity. These properties have made np-Au an attractive material to scientific community. Most studies on np-Au employ macro-scale specimens and focus on fundamental science of the material and its catalytic and sensor applications. The macro-scale specimens limit np-Au's potential in miniaturized systems, including biomedical devices. In order to address these issues, we initially describe two different methods to micropattern np-Au thin films on rigid substrates. The first method employs manually-produced stencil masks for creating millimeter-scale np-Au patterns, while the second method uses lift-off photolithography to pattern sub-millimeter-scale patterns. As the np-Au thin films are obtained by sputter-deposition process, they are compatible with conventional microfabrication techniques, thereby amenable to facile integration into microsystems. These systems include electrically-addressable biosensor platforms that benefit from high effective surface area, electrical conductivity, and gold-thiol-based surface bioconjugation. We describe cell culture, immunostaining, and image processing techniques to quantify np-Au's interaction with mammalian cells, which is an important performance parameter for some biosensors. We expect that the techniques illustrated here will assist the integration of np-Au in platforms at various length-scales and in numerous applications, including biosensors, energy storage systems, and catalysts.

We report on techniques to micropattern nanoporous gold thin films via stencil printing and photolithography, as well as methods to culture cells on the microfabricated patterns. In addition, we describe image analysis methods to characterize morphology of the material and the cultured cells using scanning electron and fluorescence microscopy techniques.

Microfabrication von Nanoporöse Gold-Patterns für Zell-Material-Interaktion Studies

Nanostructured materials with feature sizes in tens of nanometers have enhanced the performance of several technologies, including fuel cells, biosensors, ...

Synthesis of an Intein-mediated Artificial Protein Hydrogel

We present the synthesis of a highly stable protein hydrogel mediated by a split-intein-catalyzed protein trans-splicing reaction. The building blocks of this hydrogel are two protein block-copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. A highly hydrophilic random coil is inserted into one of the block-copolymers for water retention. Mixing of the two protein block copolymers triggers an intein trans-splicing reaction, yielding a polypeptide unit with crosslinkers at either end that rapidly self-assembles into a hydrogel. This hydrogel is very stable under both acidic and basic conditions, at temperatures up to 50 &#176;C, and in organic solvents. The hydrogel rapidly reforms after shear-induced rupture. Incorporation of a &#34;docking station peptide&#34; into the hydrogel building block enables convenient incorporation of &#34;docking protein&#34;-tagged target proteins. The hydrogel is compatible with tissue culture growth media, supports the diffusion of 20 kDa molecules, and enables the immobilization of bioactive globular proteins. The application of the intein-mediated protein hydrogel as an organic-solvent-compatible biocatalyst was demonstrated by encapsulating the horseradish peroxidase enzyme and corroborating its activity.

We present the synthesis of a split-intein-mediated protein hydrogel. The building blocks of this hydrogel are two protein copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. Mixing of the two protein copolymers triggers an intein trans-splicing reaction, yielding a polypeptide unit that self-assembles into a hydrogel. This hydrogel is highly pH- and temperature-stable, compatible with organic solvents, and easily incorporates functional globular proteins.

Synthese einer Intein-vermittelten Protein-Hydrogel Künstliche

We present the synthesis of a highly stable protein hydrogel mediated by a split-intein-catalyzed protein trans-splicing reaction. The building blocks of ...

Synthesis of Keratin-based Nanofiber for Biomedical Engineering

Electrospinning, due to its versatility and potential for applications in various fields, is being frequently used to fabricate nanofibers. Production of these porous nanofibers is of great interest due to their unique physiochemical properties. Here we elaborate on the fabrication of keratin containing poly (&#949;-caprolactone) (PCL) nanofibers (i.e., PCL/keratin composite fiber). Water soluble keratin was first extracted from human hair and mixed with PCL in different ratios. The blended solution of PCL/keratin was transformed into nanofibrous membranes using a laboratory designed electrospinning set up. Fiber morphology and mechanical properties of the obtained nanofiber were observed and measured using scanning electron microscopy and tensile tester. Furthermore, degradability and chemical properties of the nanofiber were studied by FTIR. SEM images showed uniform surface morphology for PCL/keratin fibers of different compositions. These PCL/keratin fibers also showed excellent mechanical properties such as Young&#39;s modulus and failure point. Fibroblast cells were able to attach and proliferate thus proving good cell viability. Based on the characteristics discussed above, we can strongly argue that the blended nanofibers of natural and synthetic polymers can represent an excellent development of composite materials that can be used for different biomedical applications.

Electrospun nanofibers have a high surface area to weight ratio, excellent mechanical integrity, and support cell growth and proliferation. These nanofibers have a wide range of biomedical applications. Here we fabricate keratin/ PCL nanofibers, using the electrospinning technique, and characterize the fibers for possible applications in tissue engineering.

Synthese von Keratin-basierten Nanofaser für Biomedizinische Technik

Electrospinning, due to its versatility and potential for applications in various fields, is being frequently used to fabricate nanofibers. Production of ...

The Synthesis of RGD-functionalized Hydrogels as a Tool for Therapeutic Applications

The use of polymers as biomaterials has provided significant advantages in therapeutic applications. In particular, the possibility to modify and functionalize polymer chains with compounds that are able to improve biocompatibility, mechanical properties, or cell viability allows the design of novel materials to meet new challenges in the biomedical field. With the polymer functionalization strategies, click chemistry is a powerful tool to improve cell-compatibility and drug delivery properties of polymeric devices. Similarly, the fundamental need of biomedicine to use sterile tools to avoid potential adverse-side effects, such as toxicity or contamination of the biological environment, gives rise to increasing interest in the microwave-assisted strategy.
The combination of click chemistry and the microwave-assisted method is suitable to produce biocompatible hydrogels with desired functionalities and improved performances in biomedical applications. This work aims to synthesize RGD-functionalized hydrogels. RGD (arginylglycylaspartic acid) is a tripeptide that can mimic cell adhesion proteins and bind to cell-surface receptors, creating a hospitable microenvironment for cells within the 3D polymeric network of the hydrogels. RGD functionalization occurs through Huisgen 1,3-dipolar cycloaddition. Some PAA carboxyl groups are modified with an alkyne moiety, whereas RGD is functionalized with azido acid as the terminal residue of the peptide sequence. Finally, both products are used in a copper catalyzed click reaction to permanently link the peptide to PAA. This modified polymer is used with carbomer, agarose and polyethylene glycol (PEG) to synthesize a hydrogel matrix. The 3D structure is formed due to an esterification reaction involving carboxyl groups from PAA and carbomer and hydroxyl groups from agarose and PEG through microwave-assisted polycondensation. The efficiency of the gelation mechanism ensures a high degree of RGD functionalization. In addition, the procedure to load therapeutic compounds or biological tools within this functionalized network is very simple and reproducible.

We present a protocol for the synthesis of RGD-functionalized hydrogels as devices for cell and drug delivery. The procedure involves copper catalyzed alkyne-azide cycloaddition (CuAAC) between alkyne-modified polyacrylic acid (PAA) and a RGD-azide derivative. The hydrogels are formed using microwave-assisted polycondensation and their physicochemical properties are investigated.

Die Synthese von RGD-funktionalisierten Hydrogele als Werkzeug für therapeutische Anwendungen

The use of polymers as biomaterials has provided significant advantages in therapeutic applications. In particular, the possibility to modify and ...

Polydimethylsiloxane-polycarbonate Microfluidic Devices for Cell Migration Studies Under Perpendicular Chemical and Oxygen Gradients

This paper reports a microfluidic device made of polydimethylsiloxane (PDMS) with an embedded polycarbonate (PC) thin film to study cell migration under combinations of chemical and oxygen gradients. Both chemical and oxygen gradients can greatly affect cell migration in vivo; however, due to technical limitations, very little research has been performed to investigate their effects in vitro. The device developed in this research takes advantage of a series of serpentine-shaped channels to generate the desired chemical gradients and exploits a spatially confined chemical reaction method for oxygen gradient generation. The directions of the chemical and oxygen gradients are perpendicular to each other to enable straightforward migration result interpretation. In order to efficiently generate the oxygen gradients with minimal chemical consumption, the embedded PC thin film is utilized as a gas diffusion barrier. The developed microfluidic device can be actuated by syringe pumps and placed into a conventional cell incubator during cell migration experiments to allow for setup simplification and optimized cell culture conditions. In cell experiments, we used the device to study migrations of adenocarcinomic human alveolar basal epithelial cells, A549, under combinations of chemokine (stromal cell-derived factor, SDF-1&#945;) and oxygen gradients. The experimental results show that the device can stably generate perpendicular chemokine and oxygen gradients and is compatible with cells. The migration study results indicate that oxygen gradients may play an essential role in guiding cell migration, and cellular behavior under combinations of gradients cannot be predicted from those under single gradients. The device provides a powerful and practical tool for researchers to study interactions between chemical and oxygen gradients in cell culture, which can promote better cell migration studies in more in vivo-like microenvironments.

The control of chemical and oxygen gradients is essential for cell cultures. This paper reports a polydimethylsiloxane-polycarbonate (PDMS-PC) microfluidic device capable of reliably generating combinations of chemical and oxygen gradients for cell migration studies, which can be practically utilized in biological labs without sophisticated instrumentation.

Polydimethylsiloxanhaltigen Polycarbonat Mikrofluidiksysteme für Zellmigrationsstudien unter Perpendicular Chemische und Sauerstoff Gradients

This paper reports a microfluidic device made of polydimethylsiloxane (PDMS) with an embedded polycarbonate (PC) thin film to study cell migration under ...

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

Synthese von Hydrogelen mit Antifouling-Eigenschaften als Membranen für die Wasserreinigung

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and ...

Ammonia Synthesis at Low Pressure

Ammonia can be synthesized at low pressure by the use of an ammonia selective absorbent. The process can be driven with wind energy, available locally in areas requiring ammonia for synthetic fertilizer. Such wind energy is often called &#34;stranded,&#34; because it is only available far from population centers where it can be directly used.
In the proposed low pressure process, nitrogen is made from air using pressure swing absorption, and hydrogen is produced by electrolysis of water. While these gases can react at approximately 400 &#176;C in the presence of a promoted conventional catalyst, the conversion is often limited by the reverse reaction, which makes this reaction only feasible at high pressures. This limitation can be removed by absorption on an ammine-like calcium or magnesium chloride. Such alkaline metal halides can effectively remove ammonia, thus suppressing the equilibrium constraints of the reaction. In the proposed absorption-enhanced ammonia synthesis process, the rate of reaction may then be controlled not by the chemical kinetics nor the absorption rates, but by the rate of the recycle of unreacted gases. The results compare favorably with ammonia made from a conventional small scale Haber-Bosch process.

Ammonia can be synthesized at low pressure by using a conventional catalyst and an ammonia selective absorbent.

Ammoniaksynthese bei niedrigem Druck

Ammonia can be synthesized at low pressure by the use of an ammonia selective absorbent. The process can be driven with wind energy, available locally in ...

Synthesis of Functionalized 10-nm Polymer-coated Gold Particles for Endothelium Targeting and Drug Delivery

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting and drug delivery are some of the applications of these AuNPs, but endothelial extracellular matrices&#39; defensive properties hamper particle uptake. To address this issue, we describe a synthesis method for ultrasmall gold nanoparticles to improve vascular delivery, with customizable functional groups and polymer lengths for further adjustments. The protocol yields 2.5 nm AuNPs that are capped with tetrakis(hydroxymethyl)phosphonium chloride (THPC). The replacement of THPC with hetero-functional polyethylene glycol (PEG) on the surface of the AuNP increases the hydrodynamic radius to 10.5 nm while providing various functional groups on the surface. The last part of the protocol includes an optional addition of a fluorophore to allow the AuNPs to be visualized under fluorescence to track nanoparticle uptake. Dialysis and lyophilization were used to purify and isolate the AuNPs. These fluorescent nanoparticles can be visualized in both in vitro and in vivo experiments due to the biocompatible PEG coating and fluorescent probes. Additionally, the size range of these nanoparticles render them an ideal candidate for probing the glycocalyx without disrupting normal vasculature function, which may lead to improved delivery and therapeutics.

We describe a method of synthesizing biocompatible 10-nm gold nanoparticles, functionalized by coating poly-ethylene glycol onto the surface. These particles can be used in vitro and in vivo for delivering therapeutics to nanoscale cellular and extracellular spaces that are difficult to access with conventional nanoparticle sizes.

Synthese von funktionalisierten 10 nm Polymer beschichteten Goldpartikeln für Targeting Endothel und Drug-Delivery

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting ...