Diese Arbeit wurde von Western Kentucky University Ogden College of Science and Engineering, einschließlich der internen Unterstützung aus dem Department Chemie und von der Office of Research (RCAP 13-8032) unterstützt. Die Unterstützung von Dr. John Andersland an der WKU Microscopy Facility (REM-Aufnahmen) und Associate Professor Yan Cao der WKU Institut für Verbrennungs Science and Engineering (BET-Analyse) ist von zentraler Bedeutung für die Durchführung dieser Arbeiten.

1. Herstellung der Emulsion <ol><li> Emulsion Inhalt <ol><li> Masse eine geeignete Menge an Salz zu 10 ml einer 0,03-M-Lösung herzustellen. Platin (IV) -chlorid Maß 0,101 g, für Zink (II) chlorid (ZnCl 2) Maßnahme 0,032 g, und Natriumchlorid (NaCl) Maßnahme 0,018 g. </li><li> In einzelnen Reagenzgläser, lösen jedes Salz in 10 ml VE-Wasser. Zur späteren Verwendung beiseite gesetzt. </li><li> Verwenden Sie ein 20-ml, verschließbaren Glasgefäß für die Inhalte im Rahmen dieses Verfahrens. Tarieren ein Gleichgewicht mit dem Glasfläschchen. </li><li> Wiegen Vinyl-terminierten Polydimethylsiloxans durch langsames Eingießen sie über einen Rührstab und in das Glasgefäß auf der Waage ruht auf Null gestellt. Man wiegt 1,02 g (entspricht 1.080 ml). HINWEIS: Die hohe Viskosität dieses Polymers macht Pipettieren unpraktisch. </li><li> Pipette 1,02 ml n-Heptan zu dem Fläschchen. 2 Tropfen nicht-ionisches Tensid (Sorbitanmonooleat) in das Fläschchen. Pipette 0,3 ml Salzlösung und 0,45 ml DI-Wasser in das Fläschchen. </li><li> Dichten Sie das Glasfläschchen durch Verschrauben Sie den Deckel fest zu. Kräftig schütteln für 60 Sekunden, um die Emulsion vor Beginn der Ultraschallbehandlung einzuleiten. </li></ol></li><li> Bau von Wasser-Ultraschallbad Vorrichtung <ol><li> Füllen Beschallungsgerät mit Wasser bis auf die minimale Füllhöhe. In 250 ml Leitungswasser zu einer 400-ml-Becherglas. Füllen Sie den 400-ml-Becherglas mit Eis, so dass der Wasserstand ist nur am Rand. </li><li> Dieses Becherglas im Inneren des wasser Ultraschallbad. Überprüfen Sie das Fill-Linie auf dem Ultraschallgerät, Einstellung, wenn nötig. Platzieren Sie einen Ring zu stehen direkt am Wasser Ultraschallbad. </li><li> Verwendung von zwei Ringständer Klammern einsetzen, positionieren, so daß ein Arm ausgefahren und senkrecht zum Ring stehen und eine weitere in Richtung der Wasserbad ausgefahren, so dass es nach unten in den Becher mit Eiswasser gefüllt zeigt. Befestigen weiterer Schelle mit dem Ring stehen, der mit einem Thermometer, die in der 400-ml-Becherglas so daß die Temperatur während der Beschallung zu überwachen. </li></ol></li><li> Emulsification Ordnung <ol><li> Platzieren der Emulsion enthaltenden Ampulle, so daß er vollständig in den 400-ml-Becher durch Befestigung in die Klemme nach unten in den Becher vorsteht getaucht. </li><li> Stellen Sie sicher, dass die Glasfläschchen mit dem PDMS-Mischung wird die Wand des Becherglases nicht berühren, um Wärme durch Reibung zu eliminieren. </li><li> Schalten Sie das Ultraschallgerät und setzen Beschallungszeit für 7 min. Weil der Emulsion ist sehr wärmeempfindlich, sicherzustellen, dass die Temperatur im Inneren des Bechers liegt zwischen 0 und 5 ° C das Beschallen. Beginnen Beschallung, sobald die Temperatur im Inneren des Bechers, ist wünschenswert. </li><li> Nach 7 min von Beschallung, entfernen Sie das Röhrchen und schütteln / Strudel für 1 min, hält die Spitze des Fläschchens, um alle Klumpen, die in der Emulsion zu bilden könnten, zu beseitigen. </li><li> Entsorgen Sie den Inhalt des Bechers. Refill mit 250 ml Wasser und Eis hinzufügen, um die Füllung innerhalb von 1 cm die Oberseite des Bechers. </li><li> Legen Sie das Fläschchen wieder in der Klemme. Tauchen Sie es unter dem Eis Wasser zu Resume Beschallung während 7 min. </li><li> Wiederholen Sie die Schritte 1.3.3, für insgesamt acht, 7-min Beschallung Perioden 1.3.6, oder bis die Beschallung erscheint homogen zu sein und keine Klumpen vorhanden sind. Lagern bei RT. ANMERKUNG: Das Emulgieren sollte für mehrere Tage stabil zu sein, sondern kann durch Beschallung, wie oben in 7-Minuten-Intervallen gewonnen werden, bis sie homogen erscheint. Lagern bei RT. </li></ol></li></ol> 2. Die Vernetzung <ol><li> Setup für die Zugabe von Triethoxysilan / Tensid-Lösung <ol><li> Pipette 5,4 ml Triethoxysilan in ein Reagenzglas. Platzieren in einem Reagenzglasgestell unter der Haube zur späteren Verwendung. </li><li> Füllen Sie einen 400-ml-Becherglas mit Eiswasser und legen Sie sie unter der Haube. Neben der 400-ml-Becher Ort ein Ring mit einer Klammer befestigt zu stehen, verlängert sich direkt über der Öffnung des Bechers. Dies wird das Eisbad für die Zugabe von Triethoxysilan zu sein. </li><li> Legen Sie eine heiße Platte auf der anderen Seite des Rings stehen. Füllen Sie einen 800-ml-Becherglas mit etwa 700 mlLeitungswasser. Legen Sie sie auf der heißen Platte. </li><li> Drehen auf der Heizplatte und Aufrechterhaltung einer Temperatur von 75 bis 85 ° C in der 800-ml-Becherglas. Befestigen Sie eine Klemme mit einem Thermometer in den Ring Ständer, so dass die Temperatur des Wassers in der 800-ml-Becher kann überwacht werden. </li><li> Erzeugen der Tensidlösung durch Auflösen von 0,5 g Natriumdodecylsulfat und 375 ml Wasser (4,62 mM). Etwa 10 ml des oberflächenaktiven Lösung auf eine saubere, leere Reagenzglas. </li><li> Befestigen Sie eine weitere Klemme an den Ring unter der Haube mit dem Tensid Reagenzglasständer befestigt, so dass seine Flüssigkeitspegel unterhalb der Oberfläche des Wassers in der 800-ml-Becherglas. Lassen Sie 10 Minuten zum Temperaturausgleich. </li><li> Befeuchten Sie ein Stück Filterpapier und legen Sie es in der Spitze eines kleinen Trichter. Setzen Sie den Stiel des Trichters in einem 250-ml-Erlenmeyerkolben und der Kolben setzen unter der Haube. </li></ol></li><li> Zugabe von Triethoxysilan <ol><li> Legen Sie die Emulsion Fläschchen in der Klemme über die Eis-Wasser-Schnabeler im Inneren der Kapuze. Positionierung des PDMS-Mischung in der Klemme, so daß die Kolbeninhalt unterhalb der Oberfläche des Wassers. Die Zugabe von Triethoxysilan bewirkt eine exotherme Reaktion, so dass die Emulsion muß, um seine Struktur beizubehalten kalt gehalten werden. </li><li> Entfernen Sie den Deckel von der Glasfläschchen in den gasförmigen Aufbau zu vermeiden. </li><li> Gießen Sie langsam das Teströhrchen, das Triethoxysilan in das Glasfläschchen in einem kontinuierlichen Strom über einen Zeitraum von etwa 10 s (etwa 0,5 ml / sec). Vorsicht: Die Zugabe von Triethoxysilan initiiert eine exotherme Reaktion und die Freisetzung von ätzenden Chlorwasserstoff (HCl) -Gas. Das Fläschchen wird sehr heiß und ein giftiges Gas wird aus der Mischung zu entwickeln. Nicht rühren den Inhalt während der Zugabe des Triethoxysilan. </li><li> Nach der Zugabe von Triethoxysilan komplett vorsichtig rühren Sie den Inhalt mit einem Glas Rührstab beim Tragen eines Wärmeschutzhandschuh. Warten Sie 2 Minuten oder bis die Gashaltestellen weiterentwickelt aus dem Fläschchen. </li><li> Folldurch Vernetzung gibt es keine Phasentrennung in der Probe sichtbar. Wenn Klumpen vorhanden sind, versiegeln Sie die Durchstechflasche und schütteln Sie konsequent für 20 Sekunden, während Sie das Fläschchen mit dem Deckel. </li></ol></li><li> Bead Produktions <ol><li> Verwenden Sie ein sauberes, Glas Pasteur-Pipette, um das vernetzte Emulsion aus dem Glasfläschchen zu ziehen. Hinzufügen der vernetzten Emulsion tropfenweise zu der Tensidlösung in das Teströhrchen nehmen so wenig Zeit wie möglich in zwischen den Tropfen (der zwischen 75 und 85 ° C gehalten werden sollte). </li><li> 30 Sekunden bis 1 Minute nach der Zugabe der Emulsion wird die Tensidlösung langsam beginnen, Gas entwickeln, während sich Feststoffe im Inneren der Teströhrchen zu bilden. </li><li> Während das Tragen Wärmeschutzhandschuhe tragen, nehmen Sie das Reagenzglas aus der Klemme und gießen Sie den gesamten Inhalt in die Filtervorrichtung unter der Haube. Filter für 5 min. Entfernen Sie das Filterpapier aus dem Filter. </li><li> Übertragen Sie die filtrierten Feststoffe auf ein Uhrglas und separater Perlen für O / N Trocknung unter der hood. Reinigung der Perlen können unbestimmte Zeit verschoben werden. Shop getrockneten Kügelchen bei RT in einem verschlossenen Glasgefäß, bis sie benötigt, und sauber unmittelbar vor der Verwendung. </li></ol></li><li> Bead Reinigung <ol><li> Erstellen Sie eine andere Filtervorrichtung unter der Haube und legen Sie die getrockneten Kugeln im Inneren des Trichters auf dem Filterpapier. </li><li> Verwenden Sie einen Kunststoff-Spritzflasche mit DI-Wasser gefüllt, um die Perlen vorsichtig spülen, bewegen sie um etwas, um sicherzustellen, dass alle die Perlen gespült werden. </li><li> Lassen Sie die Perlen trocknen 1 h, indem sie auf einem Uhrglas unter der Haube. Verwenden Sie eine Waschflasche mit Hexan gefüllt, um die Kügelchen mit der gleichen Methode zum Spülen mit Wasser spülen. </li><li> Legen Sie die Perlen auf einem Uhrglas. Legen Sie das Uhrglas und die Perlen unter der Haube, um zu trocknen. </li><li> Nachdem die Kügelchen vollständig trocken sind, legen Sie sie in einer kleinen verschließbaren Glasgefäß und lagern bei RT für die zukünftige Verwendung. </li></ol></li><li> Montage der Korne für SEM und SEM-Analyse-Einstellungen <ol><li> Legen Sie einen Streifen von double seitigen Kohlen leitende Band an der Spitze des Stutzens, auf dem die Perlen angebracht werden. Mit einer Schere, schneiden Sie auf der Stummel, keine Band hängt über die Kanten zu gewährleisten. </li><li> Legen Sie ein Stück Filterpapier unter dem Stummel auf einer ebenen Fläche. Entfernen der Deckschicht vom Band, so daß die Klebeunterseite freiliegt. </li><li> Vorsichtig gießen Sie die Perlen auf der Stummel. Einige Perlen werden auf das Band zu bleiben, aber die meisten werden auf dem Filterpapier abprallen und Land. Gießen Sie diese zurück in die Flasche, wenn sie blieben auf dem Filterpapier. Wiederholen Sie gegebenenfalls Waschen keine Kügelchen (nach 2.4.2 bis 2.4.5), die kontaminiert werden. </li><li> Um sicherzustellen, dass die Perlen auf der Stummel sicher, verwenden Sie eine Ballonspritze und leicht zu blasen sehr eng mit dem Stummeloberfläche. Gießen Sie mehr Perlen über den Stub, wenn nur wenige auf das Band geklebt. Stellen Sie sicher, dass alle Perlen sind, bevor Sie den Stummel in den SEM-Kammer und Evakuieren sicher. </li><li> Sobald die Proben ordnungsgemäß montiert sind sie nun bereit, SEM anal unterziehenlyse 15. Sammle Bilder in LOW VAC-Modus bei 15 keV, die Auflösung der Oberflächenmerkmale der Wulst zu optimieren. </li></ol></li></ol>

<ol>
	<li>Pedraza, E., Brady, A. C., Fraker, C. A., Stabler, C. L. <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+macroporous+poly(dimethylsiloxane)+scaffolds+for+tissue+engineering+applications.">Synthesis of macroporous poly(dimethylsiloxane) scaffolds for tissue engineering applications.</a> J. Biomater. Sci., Polym. Ed. 24 (9), 1041-1056 (2013).</li><li>Ratner, B. D., Bryant, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomaterials:+Where+we+have+been+and+where+we+are+going.">Biomaterials: Where we have been and where we are going.</a> Annu. Rev. Biomed. Eng. 6, 41-75 (2004).</li><li>B&#233;langer, M. C., Marois, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemocompatibility,+biocompatibility,+inflammatory+and+in+vivo+studies+of+primary+reference+materials+low-density+polyethylene+and+polydimethylsiloxane:+A+review.">Hemocompatibility, biocompatibility, inflammatory and in vivo studies of primary reference materials low-density polyethylene and polydimethylsiloxane: A review.</a> J. Biomed. Mater. 58 (5), 467-477 (2001).</li><li>Kobayashi, T., Saitoh, H., Fujii, N., Hoshino, Y., Takanashi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Porous+membrane+of+polydimethylsiloxane+by+hydrosilylation+cure:+characteristics+of+membranes+having+pores+formed+by+hydrogen+foams.">Porous membrane of polydimethylsiloxane by hydrosilylation cure: characteristics of membranes having pores formed by hydrogen foams.</a> J. Appl. Polym. Sci. 50 (6), 971-979 (1993).</li><li>Yager, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+diagnostic+technologies+for+global+public+health.">Microfluidic diagnostic technologies for global public health.</a> Nature. 442 (7101), 412-418 (2006).</li><li>Yu, P., Lu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PDMS+used+in+microfluidic+devices:+principles,+devices+and+technologies.">PDMS used in microfluidic devices: principles, devices and technologies.</a> Adv. Mater. Sci. Res. 11, 443-450 (2011).</li><li>Zhou, J., Khodakov, D. A., Ellis, A. V., Voelcker, N. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+modification+for+PDMS-based+microfluidic+devices.">Surface modification for PDMS-based microfluidic devices.</a> Electrophoresis. 33 (1), 89-104 (2012).</li><li>Spietelun, A., Pilarczyk, M., Kloskowski, A., Namie&#347;nik, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyethylene+glycol-coated+solid-phase+microextraction+fibres+for+the+extraction+of+polar+analytes&#8212;A+review.">Polyethylene glycol-coated solid-phase microextraction fibres for the extraction of polar analytes&#8212;A review.</a> Talanta. 87, 1-7 (2011).</li><li>Vas, G., V&#233;key, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solid-phase+microextraction:+a+powerful+sample+preparation+tool+prior+to+mass+spectrometric+analysis.">Solid-phase microextraction: a powerful sample preparation tool prior to mass spectrometric analysis.</a> J. Mass Spectrom. 39 (3), 233-254 (2004).</li><li>Odziemkowski, M., Koziel, J. A., Irish, D. E., Pawliszyn, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sampling+and+Raman+confocal+microspectroscopic+analysis+of+airborne+particulate+matter+using+poly(dimethylsiloxane)+solid+phase+microextraction+fibers.">Sampling and Raman confocal microspectroscopic analysis of airborne particulate matter using poly(dimethylsiloxane) solid phase microextraction fibers.</a> Anal. Chem. 73 (13), 3131-3139 (2001).</li><li>Grosse, M. T., Lamotte, M., Birot, M., Deleuze, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+microcellular+polysiloxane+monoliths.">Preparation of microcellular polysiloxane monoliths.</a> J. Polym. Sci., Part A: Polym. Chem. 46 (1), 21-32 (2007).</li><li>Sun, W., Yan, X., Zhu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis,+porous+structure,+and+underwater+acoustic+properties+of+macroporous+cross-linked+copolymer+beads.">Synthesis, porous structure, and underwater acoustic properties of macroporous cross-linked copolymer beads.</a> Colloid Polym. Sci. 290 (1), 73-80 (2012).</li><li>Dufaud, O., Favre, E., Sadtler, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Porous+elastomeric+beads+from+crosslinked+emulsions.">Porous elastomeric beads from crosslinked emulsions.</a> J. Appl. Polym. Sci. 83 (5), 967-971 (2002).</li><li>Farmer, B. C., Mason, M., Nee, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concave+porosity+non-polar+beads+by+a+modified+microbubble+fabrication.">Concave porosity non-polar beads by a modified microbubble fabrication.</a> Mater. Lett. 98, 105-107 (2013).</li><li>Flegler, S. L., Heckman, J. W., Klomparens, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Scanning and Transmission Electron Microscopy: An Introduction. , 151-155 (1995).</li><li>Brunauer, S., Emmett, P. H., Teller, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adsorption+of+Gases+in+Multimolecular+Layers.">Adsorption of Gases in Multimolecular Layers.</a> J. Am. Chem. Soc. 60 (2), 309-319 (1938).</li><li>Sing, K. S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+porous+materials:+past,+present+and+future.">Characterization of porous materials: past, present and future.</a> Colloids Surf. A. 241 (1), 3-7 (2004).</li></ol>

The authors have nothing to disclose.

Die unter Verwendung dieses Protokolls (und durch Einstellung der Elektrolyt-Konzentration und Identität) hergestellten Kügelchen grundlegend von denen mit einer niedrigen Ionenstärke Emulsion hergestellte, wie durch den Vergleich der 1A zu den anderen SEM-Bilder in 1 zu sehen. Unsere anfänglichen Bericht verwendet PtCl 4 mit der Absicht, die Polymerisation Vernetzung weiter zu katalysieren, in der wässrig-aliphatische-Schnittstelle 14. In diesem Bericht wurde...

Polydimethylsiloxane (PDMS) is one of the most widely used silicone compounds. Its biocompatibility has led to widespread use in implant and other biomedical engineering structures1,2. It is trivially cross-linked into elastic structures using an organosilyl compound (such as triethoxysilane), a simple and reliable procedure which has made it useful for cast polymer applications where some flexibility is required3. Once cross-linked, PDMS is largely inert, particularly in biological conditions, and is therefore useful for a variety of food and medical applications4,5. Ease of casting, chemical inertness, and hydrophobicity have made it a natural choice for microfluidic devices6,7. Its affinity for non-halogenated, non-polar organic compounds has made it a popular stationary phase in separations chemistry8-10. 
Recently, microbubble fabrications have been used to generate porous beads for use as catalyst structural substrates or in chemical separations11,12. In both applications, ideal materials will have a maximized surface-area-to-volume (SAV) ratio for best efficiency. In a microbubble fabrication process, microstructuring of materials is typically accomplished by isolating the polymer in aliphatic &#8220;microbubbles&#8221; by emulsification in an aqueous continuous phase. The initial report of microporous PDMS beads produced them by mechanical emulsification of two phases (aliphatic and aqueous)13. The stock PDMS liquid (and its cross-linking agent) is dissolved into the aliphatic phase, which is structured into microscopic beads by being forced to cavitate within the (continuous) aqueous phase. The emulsification is stabilized by the addition of a non-ionic surfactant. When the emulsion is added dropwise to a heated bath, solid beads form by agglomeration of the microbubbles into clusters of tiny spheres of cross-linked PDMS. Our goal in this protocol is to modify this procedure to develop beads with an inverted porosity to improve the SAV ratio of the material.
As reported previously, control of the beads can be directed to some extent by the aliphatic:aqueous ratios in the emulsion. However, we have reported recently that addition of platinum(IV) chloride (PtCl4) inverts the porosity: materials are formed in which the PDMS is riddled with concave pores14. This indicates that the aqueous layer cavitates inside the aliphatic one, despite having similar aliphatic:aqueous ratios to those published in the original work13. The primary advantage of our method is that this concave porosity should naturally result in an increased SAV ratio, and thus, improved efficiency for analytical chemistry applications. While we are continuing to explore the specific effects of the addition of the platinum compound, we show here that the same effect can be accomplished using any aqueously soluble ionic compound, though perhaps to a reduced extent. Because our techniques also differ in some key aspects from what has been previously reported, we present our protocols here as a video to encourage others to extend our methods. Most notably, we use a common bath sonicator of the type used to clean glassware or other equipment, rather than the (considerably more expensive) probe sonicator often used in microbubble fabrication. This adjusted approach to the microbubble fabrication procedure could potentially be extended for the production of large quantities of bulk materials as well, creating porous sheets or slabs which could have applications for biomedical devices, aerospace and automotive industry, or substrates for chemical catalysis. Users seeking to generate high-SAV-ratio, microstructured materials using other similar polymers for such analyses may find that our protocols can be extended to any polymer for which the microbubble emulsion technique can be applied.

<table border="0">
	<tbody>
		<tr>
			<td>Poly(dimethylsiloxane), vinyl terminated</td>
			<td>Sigma-Aldrich</td>
			<td>68083-19-2</td>
			<td></td>
		</tr>
		<tr>
			<td>n-Heptane</td>
			<td>Sigma-Aldrich</td>
			<td>142-82-5</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>Triethoxysilane</td>
			<td>Sigma-Aldrich</td>
			<td>998-30-1</td>
			<td>Flammable, Accutely Toxic</td>
		</tr>
		<tr>
			<td>Sorbitan Monoleate (Span-80)</td>
			<td>Fluker</td>
			<td>1338-43-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Platinum (IV) Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>13454-96-1</td>
			<td>Accutely Toxic</td>
		</tr>
		<tr>
			<td>Zinc (II) Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>7646-85-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>2.8L Water Bath Sonicator</td>
			<td>VWR</td>
			<td>97043-964</td>
			<td></td>
		</tr>
	</tbody>
</table>

microbubble fabrication of concave-porosity pdms beads

Microbubble fabrication (by use of a fine emulsion) provides a means of increasing the surface-area-to-volume (SAV) ratio of polymer materials, which is particularly useful for separations applications. Porous polydimethylsiloxane (PDMS) beads can be produced by heat-curing such an emulsion, allowing the interface between the aqueous and aliphatic phases to mold the morphology of the polymer. In the procedures described here, both polymer and crosslinker (triethoxysilane) are sonicated together in a cold-bath sonicator. Following a period of cross-linking, emulsions are added dropwise to a hot surfactant solution, allowing the aqueous phase of the emulsion to separate, and forming porous polymer beads. We demonstrate that this method can be tuned, and the SAV ratio optimized, by adjusting the electrolyte content of the aqueous phase in the emulsion. Beads produced in this way are imaged with scanning electron microscopy, and representative SAV ratios are determined using Brunauer&#8211;Emmett&#8211;Teller (BET) analysis. Considerable variability with the electrolyte identity is observed, but the general trend is consistent: there is a maximum in SAV obtained at a specific concentration, after which porosity decreases markedly.

Repräsentative SEM-Bilder von Kügelchen, die aus Emulsionen mit unterschiedlichen Elektrolytbedingungen sind in Abbildung 1 dargestellt. 1A zeigt eine Wulst ähnlich denen von Dufaud erhalten, et al. 13, die unter Verwendung unserer Verfahren, ohne die Zugabe von irgendeinem Elektrolyten. Kügelchen in 1B-D gezeigt ist, was zu unterschiedlichen Morphologien für jedes Metallion. Für alle gezeigten Bilder wurden 300 ul von 0,03 M-Elektrolytlösungen anstelle von 30...

Watch this Scientific Journal Video about Microbubble Fabrication of Concave-porosity PDMS Beads at JoVE.com

Microbubble Fabrication of Concave-porosity PDMS Beads

Procedures used to generate microstructured concave-porosity polydimethylsiloxane beads are presented. Effects of electrolyte concentration and identity within the aqueous phase are particularly emphasized.

Mikroblasen Herstellung von Konkav-Porosität PDMS Beads

Microbubble fabrication (by use of a fine emulsion) provides a means of increasing the surface-area-to-volume (SAV) ratio of polymer materials, which is ...

microbubble-fabrication-of-concave-porosity-pdms-beads

Research

JoVE Journal

Chemistry

8.2K Aufrufe.  Western Kentucky University. Procedures used to generate microstructured concave-porosity polydimethylsiloxane beads are presented. Effects of electrolyte concentration and identity within the aqueous phase are particularly emphasized. 

Serie: Microbubble Fabrication of Concave-porosity PDMS Beads

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

Herstellung von großflächigen Freistehende ultradünne Polymerfilme

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

Forschung

Chemie

Flow-pattern Guided Fabrication of High-density Barcode Antibody Microarray

Antibody microarray as a well-developed technology is currently challenged by a few other established or emerging high-throughput technologies. In this report, we renovate the antibody microarray technology by using a novel approach for manufacturing and by introducing new features. The fabrication of our high-density antibody microarray is accomplished through perpendicularly oriented flow-patterning of single stranded DNAs and subsequent conversion mediated by DNA-antibody conjugates. This protocol outlines the critical steps in flow-patterning DNA, producing and purifying DNA-antibody conjugates, and assessing the quality of the fabricated microarray. The uniformity and sensitivity are comparable with conventional microarrays, while our microarray fabrication does not require the assistance of an array printer and can be performed in most research laboratories. The other major advantage is that the size of our microarray units is 10 times smaller than that of printed arrays, offering the unique capability of analyzing functional proteins from single cells when interfacing with generic microchip designs. This barcode technology can be widely employed in biomarker detection, cell signaling studies, tissue engineering, and a variety of clinical applications.

This protocol outlines the fabrication of a large-scale, multiplexed two-dimensional DNA or antibody array, with potential applications in cell signaling studies and biomarker detection.

Strömungsmuster Guided Herstellung von High-Density-Barcode Antikörper Microarray

Antibody microarray as a well-developed technology is currently challenged by a few other established or emerging high-throughput technologies. In this ...

Immobilization of Multi-biocatalysts in Alginate Beads for Cofactor Regeneration and Improved Reusability

We have recently developed a simple, reusable and coupled whole-cell biocatalytic system with the capability of cofactor regeneration and biocatalyst immobilization for improved production yield and sustained synthesis. Described herewith is the experimental procedure for the development of such a system consisting of two E. coli strains that express functionally complementary enzymes. Together, these two enzymes can function co-operatively to mediate the regeneration of expensive cofactors for improving the product yield of the bioreaction. In addition, the method of synthesizing an immobilized form of the coupled biocatalytic system by encapsulation of whole cells in calcium alginate beads is reported. As an example, we present the improved biosynthesis of L-xylulose from L-arabinitol by coupling E. coli cells expressing the enzymes L-arabinitol dehydrogenase or NADH oxidase. Under optimal conditions and using an initial concentration of 150 mM L-arabinitol, the maximal L-xylulose yield reached 96%, which is higher than those reported in the literature. The immobilized form of the coupled whole-cell biocatalysts demonstrated good operational stability, maintaining 65% of the yield obtained in the first cycle after 7 cycles of successive re-use, while the free cell system almost completely lost the catalytic activity. Therefore, the methods reported here provides two strategies that could help improve the industrial production of L-xylulose, as well as other value-added compounds requiring the use of cofactors in general.

Presented is the protocol for co-immobilizing whole-cell biocatalysts for cofactor regeneration and improved reusability, using the production of L-xylulose as an example. The cofactor regeneration is achieved by coupling two Escherichia coli strains expressing functionally complementary enzymes; the whole-cell biocatalyst immobilization is achieved by cell encapsulation in calcium alginate beads.

Immobilisierung von Multi-Biokatalysatoren in Alginatbeads für Kofaktorregenerierung und verbesserte Reusability

We have recently developed a simple, reusable and coupled whole-cell biocatalytic system with the capability of cofactor regeneration and biocatalyst ...

Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance.

We present an extensive study on the effects of different fabrication methods for organic/inorganic perovskite thin films by comparing crystal structures, density of states, energy levels, and ultimately the solar cell performance.

Einfluss von Hybrid Perowskit-Herstellungsverfahren auf Filmbildung, Elektronische Struktur und Leistung der Solarzelle

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

Herstellung und Prüfung von photonischen Thermometer

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three preparation methods are described: (a) the incorporation of metal salts into silica or alumina wet gels using an impregnation method; (b) the incorporation of metal salts into alumina wet gels using a co-precursor method; and (c) the addition of metal nanoparticles directly into a silica aerogel precursor mixture. The methods utilize a hydraulic hot press, which allows for rapid (&#60;6 h) supercritical extraction and results in aerogels of low density (0.10 g/mL) and high surface area (200-800 m2/g). While the work presented here focuses on the use of copper salts and copper nanoparticles, the approach can be implemented using other metal salts and nanoparticles. A protocol for testing the three-way catalytic ability of these aerogels for automotive pollution mitigation is also presented. This technique uses custom-built equipment, the Union Catalytic Testbed (UCAT), in which a simulated exhaust mixture is passed over an aerogel sample at a controlled temperature and flow rate. The system is capable of measuring the ability of the catalytic aerogels, under both oxidizing and reducing conditions, to convert CO, NO and unburned hydrocarbons (HCs) to less harmful species (CO2, H2O and N2). Example catalytic results are presented for the aerogels described.

Here we present protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms. Methods for preparing materials using copper salts and copper-containing nanoparticles are featured. Catalytic testing protocols demonstrate the effectiveness of these aerogels for three-way catalysis applications.

Herstellung und Prüfung von katalytischen Aerogelen über schnelle überkritische Extraktion vorbereitet

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

Preparation of Poly(pentafluorophenyl acrylate) Functionalized SiO2 Beads for Protein Purification

We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent immunoprecipitation (IP) application. The poly(PFPA) grafted surface is prepared via a simple two-step process. In the first step, 3-aminopropyltrimethoxysilane (APTMS) is deposited as a linker molecule onto the silica surface. In the second step, poly(PFPA) homopolymer, synthesized via the reversible addition and fragmentation chain transfer (RAFT) polymerization, is grafted to the linker molecule through the exchange reaction between the pentafluorophenyl (PFP) units on the polymer and the amine groups on APTMS. The deposition of APTMS and poly(PFPA) on the silica particles are confirmed by X-ray photoelectron spectroscopy (XPS), as well as monitored by the particle size change measured via dynamic light scattering (DLS). To improve the surface hydrophilicity of the beads, partial substitution of poly(PFPA) with amine-functionalized poly(ethylene glycol) (amino-PEG) is also performed. The PEG-substituted poly(PFPA) grafted silica beads are then immobilized with antibodies for IP application. For demonstration, an antibody against protein kinase RNA-activated (PKR) is employed, and IP efficiency is determined by Western blotting. The analysis results show that the antibody immobilized beads can indeed be used to enrich PKR while non-specific protein interactions are minimal.

Preparation of Polypentafluorophenyl acrylate Functionalized SiO2 Beads for Protein Purification

A protocol for the preparation of poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads is presented. The poly(PFPA) functionalized surface is then immobilized with antibodies and used successfully for the protein separation through immunoprecipitation.

Vorbereitung der Poly(pentafluorophenyl acrylate) funktionalisiert SiO2 Perlen Proteinreinigung

We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent ...

Fabrication of Thin Film Silver/Silver Chloride Electrodes with Finely Controlled Single Layer Silver Chloride

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin film silver electrodes. Thin film silver electrodes sized 80 &#181;m x 80 &#181;m and 160 &#181;m x 160 &#181;m were sputtered on quartz wafers with a chromium/gold (Cr/Au) layer for adhesion. After passivation, polishing and cathodic cleaning processes, the electrodes underwent galvanostatic oxidation with consideration of Faraday&#39;s Law of Electrolysis to form smooth layers of AgCl with a designated degree of coverage on top of the silver electrode. This protocol is validated by inspection of scanning electron microscope (SEM) images of the surface of the fabricated Ag/AgCl thin film electrodes, which highlights the functionality and performance of the protocol. Sub-optimally fabricated electrodes are fabricated as well for comparison. This protocol can be widely used to fabricate Ag/AgCl electrodes with specific impedance requirements (e.g., probing electrodes for impedance sensing applications like impedance flow cytometry and interdigitated electrode arrays).

This paper aims to present a method to form smooth and well-controlled films of silver chloride (AgCl) with designated coverage on top of thin film silver electrodes.

Herstellung von Dünnschichtsilber/Silberchloridelektroden mit fein kontrollierten einlagigen Silberchlorid

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin ...

Porphyrin-modifizierte Kügelchen in der Durchflusszytometrie

Porphyrin-Modified Beads for Use as Compensation Controls in Flow Cytometry

Flow cytometry can rapidly characterize and quantify diverse cell populations based on fluorescence measurements. The cells are first stained with one or more fluorescent reagents, each functionalized with a different fluorescent molecule (fluorophore) that binds to cells selectively based on their phenotypic characteristics, such as cell surface antigen expression. The intensity of fluorescence from each reagent bound to cells can be measured on the flow cytometer using channels that detect a specified range of wavelengths. When multiple fluorophores are used, the light from individual fluorophores often spills over into undesired detection channels, which requires a correction to the fluorescence intensity data in a process called compensation. 
Compensation control particles, typically polymer beads bound to a single fluorophore, are needed for each fluorophore used in a cell labeling experiment. Data from compensation particles from the flow cytometer are used to apply a correction to the fluorescence intensity measurements. This protocol describes the preparation and purification of polystyrene compensation beads covalently functionalized with the fluorescent reagent meso-tetra(4-carboxyphenyl) porphine (TCPP) and their application in flow cytometry compensation. In this work, amine-functionalized polystyrene beads were treated with TCPP and the amide coupling reagent EDC (N-(3-dimethylaminopropyl)-N&#8242;-ethylcarbodiimide hydrochloride) at pH 6 and at room temperature for 16 h with agitation. The TCPP beads were isolated by centrifugation and resuspended in a pH 7 buffer for storage. TCPP-related particulates were observed as a byproduct. The number of these particulates could be reduced using an optional filtration protocol. The resultant TCPP beads were successfully used on a flow cytometer for compensation in experiments with human sputum cells labeled with multiple fluorophores. The TCPP beads proved stable following storage in a refrigerator for 300 days.

Autor im Rampenlicht: Porphyrin-modifizierte Beads für den Einsatz als Kompensationskontrollen in der Durchflusszytometrie  

The protocol describes how porphyrin-based compensation beads for flow cytometry are prepared by the reaction of amine-functionalized polystyrene beads with the porphyrin TCPP and the amide coupling reagent EDC. A filtration procedure is used to reduce the particulate byproducts.

Porphyrin-modifizierte Beads zur Verwendung als Kompensationskontrollen in der Durchflusszytometrie

Flow cytometry can rapidly characterize and quantify diverse cell populations based on fluorescence measurements. The cells are first stained with one or ...