DCH, MB und FK wurden von einem EPSRC Folgen auf Fonds unterstützt. BL-V und DS wurden jeweils durch MRC PhD student unterstützt. KC wurde durch Mittel aus dem UK Regenerative Medizin-Plattform unterstützt.

1. Synthese von PHNGAD (Poly [1,6-hexanodiol / Neopentylglykol / Di (ethylenglykol)--alt Adipinsäure] diol) <img alt="Schema 1" fo:content-width="5in" src="/files/ftp_upload/51723/51723scheme1.jpg" width="500" /> Schema 1: Synthese von PHNAGD Schematische Darstellung der Synthese von PHNAGD.. PHNAGD wurde durch Umsetzung von 1,6-Hexanodiol, Diethylenglykol, neoppentyl Glykol und Adipinsäure hergestellt. PHNAGD, Poly [1,6-hexanodiol / Neopentylglykol / Di (ethylenglykol)--alt Adipinsäure] diol. <ol><li> Anwenden der Wärmebehandlung auf die Monomeren, 1,6-Hexandiol, Di (ethylenglykol) und Neopentylglycol bei 40 ° C für 48 Stunden in einem Vakuumofen, um restliches Wasser zu entfernen. Lassen Sie die Kälte auf RT unter Vakuum. </li><li> Hinzufügen 22 mmol eines jeden Monomers und Adipinsäure (55 mMol) in einen Zweihalsrundkolben, der mit einem Rühren, ausgestattet und mit einer Dean-Stark-Apparatur angeschlossen. </li><li> Legen Sie die gesamte Baugruppe im Vakuum und sanft erhitzen glassware bei 40 ° C für 6 Stunden, um jegliche Feuchtigkeitsaufnahme während der Zugabe der Chemikalien in den Kolben zu verhindern. </li><li> Fügen über eine Spritze, Tropfen für Tropfen, 0,0055 mol des Katalysators Titan (IV) butylat. </li><li> Das Reaktionsgemisch wird bei 180 ° C unter einer N 2 Atmosphäre für 24 Stunden, zu sammeln und das restliche Wasser in einer Dean-Stark-Falle. Lassen Sie das Produkt auf RT abkühlen. </li></ol> 2. Synthese von PU134 <img alt="Schema 2" fo:content-width="5in" src="/files/ftp_upload/51723/51723scheme2.jpg" width="500" /> Schema 2: Synthese von PU134 Schematische Darstellung der Synthese von Polyurethan 134 PU134 wurde durch die Umsetzung von 1,0 Äquivalenten eines PHNGAD mit 2,0 Äquivalenten eines 4,4 &#39;-Methylenbis (phenylisocyanat) hergestellt, gefolgt von der Zugabe von 1,0. equiv eines 1,4-Butandiol Kettenverlängerungs. <ol><li> Mischen ein Äquivalent der Polyol PHNGAD (Mn ~ 1.800 Da, 3.2 mmol) mit zwei Äquivalenten 4&quot;4-Methylenbis (phenylisocyanat) (6,4 mmol) in wasserfreiem N, N-Dimethylformamid (12 ml). </li><li> Rühre das Reaktionsgemisch bei 70 ° C unter einer N 2 Atmosphäre. </li><li> Fügen über eine Spritze, Tropfen für Tropfen den Katalysator Titan (IV) butylat (0,8% wt). </li><li> Nach 1 Stunde, Hinzufügen eines Äquivalents des Kettenverlängerers 1,4-Butandiol (3,2 mmol). Erhöhung der Temperatur auf 90 ° C und rührt 24 h unter einer N 2 Atmosphäre. </li><li> Nach der Reaktion sammeln das Polyurethan durch Ausfällung durch Zugabe von Diethylether (Hexan oder Wasser kann auch verwendet werden) tropfenweise zu der Reaktionslösung, bis der Niederschlag auftritt. </li><li> Zentrifugieren der Lösung bei 5.300 × g für 5 min. </li><li> Dekantiert und trocknet bei 40 ° C in einem Vakuumofen, bis das Lösungsmittel verdampft. Hinweis: Um sicherzustellen, daß das Endprodukt der Reaktion besitzt die richtigen Parameter für den Molekulargewichtsverteilung, die funktionelle groups des Polymers und der Schmelz und Glasübergangstemperaturen können verschiedene analytische Techniken und Verfahren verwendet werden, wie Gelpermeationschromatographie oder FITR Spektroskopie. </li></ol> 3. Vorbereitung der PU134 Lösungen <ol><li> Wiegen 200 mg PU134 in eine Glasflasche. </li><li> Verdünnen PU134 bis zu einer Endkonzentration von 2% in einer Reihe von Lösemittel: Chloroform, eine Kombination von Chloroform und Toluol im Verhältnis 1: 1, Tetrahydrofuran und einer Kombination aus Tetrahydrofuran und Dichlormethan im Verhältnis 1: 1. Hinweis: Die Wahl der richtigen Lösungsmittel variiert in Abhängigkeit von dem Polymer zu verwenden. Unterschiedlichen Lösungsmitteln unterschiedliche Siedepunkte besitzen, die die Solubilisierung des Polymers beeinflussen kann. </li><li> Schütteln der Lösung kräftig für 20 min bei RT mit einer Schüttelmaschine bei einer Geschwindigkeit von 200 mot / min, bis die Lösung homogen wird und kein Niederschlag beobachtet. </li></ol> 4. Beschichtung von Glasobjektträger mit PU134 <ol><li> Legen Sie eine round 15 mm 2 Deckglas auf dem Spin Coater. </li><li> Bewerben 50 ul der PU134-Lösung in jede mit einer Pipette. Stellen Sie die Lautstärke der PU134 Lösung entsprechend für die erforderliche Deck Größe halten die Volumen zu Oberfläche Verhältnis proportional. </li><li> Drehen Sie jedes Deckglas für 7 sec bei 23 x g. </li><li> Luft trocknen Deckglas bei RT für mindestens 24 Stunden vor der Sterilisation. </li></ol> 5. Die Bestrahlung von Coverslip <ol><li> Gamma-Bestrahlung mit Polymer beschichteten Deckglas durch Anlegen einer Dosis von 10 Graustufen mit einer Labor-Strahler für 12 min. </li><li> UV-Bestrahlung mit Polymer beschichtete Deckglas mit einer 30 W, UV-Lampe für 16 min auf jeder Seite. </li><li> Platzieren des mit Polymer beschichteten Deckglas in einem geeigneten Gewebekulturplatte nach dem Foliengröße. </li></ol> 6. Rasterelektronenmikroskopie <ol><li> Goldbeschichtungspolymer Deck durch Sputtern für 200 s in einer Atmosphäre von 5 x 10 -1 mbar Druck. </li><li> Capture the Mikrogrammraphs des mit Polymer beschichteten Deckglas mit einem Rasterelektronenmikroskop bei einer Beschleunigungsspannung von 20 kV in der Sekundärelektronenabbildungsmodus. </li></ol> 7. Atomic Force Microscopy Beobachtungen <ol><li> Abtasten einer Fläche von 20 x 20 um für die Polymeroberfläche. </li><li> Eine Scan-Rate von 1,32 Hz bis 1,60 Hz. </li><li> Einrichtung einer Auflösung von 512 x 512 Pixel in der abgetasteten Bereich. </li><li> Berechnen Sie das quadratische Mittel (RMS oder RQ) der Beschichtung durch Verwendung der durchschnittlichen Höhe der Abweichungen vom Mittelwert Bilddaten Ebene genommen, ausgedrückt als: <img fo:content-width="1in" src="/files/ftp_upload/51723/51723eq1.jpg" width="123" /> Wobei Zi die aktuelle Z-Wert ist, und N die Anzahl von Punkten innerhalb des bestimmten Gebiets. </li><li> 7.5 Berechnen Sie die Abweichung oder mittlere Oberflächenrauigkeit (Ra) des Bildes mit, <img fo:content-width="1.5in" src="/files/ftp_upload/51723/51723eq2.jpg" width="154" /> Wobei Z (x) ist die Funktion, t beschreibter Oberflächenprofil in der Höhe (Z) und Position (x) der Probe über die Bewertungslänge &quot;L&quot; analysiert. Ra stellt den Mittelwert der Oberfläche relativ zu der Mittelebene. </li></ol> 8. Zellkultur und Differenzierung <ol><li> Kultur und differenzieren die humane embryonale Stammzelllinie (hES) H9 als in Hay 17 beschrieben. </li><li> Lösen Zellen unter Verwendung eines Reagens Dissoziation und Ausstrich sie auf PU134 beschichtete Objektträger an Tag 9 des Differenzierungsprozesses, in Gegenwart von einem serumfreien Medium, wie in Szkolnicka 18,19 beschreiben. Anmerkung: Die Verwendung eines enzymatischen Zell Dissoziation physikalischen Zellablösung bevorzugt. </li></ol> 9. Cytochrom-P450-Funktionstest <ol><li> Messen CYP3A-Aktivität nach der Anleitung des Herstellers. </li><li> HESC abgeleitet Hepatozyten an Tag 13 oder Tag 19, und Medien inkubieren ohne Zellen - als Negativkontrolle, mit der entsprechenden substraß für 5 h bei 37 ° C aufweist. </li><li> Sammeln Ständen von Zellen und Medien, führen Sie den Test nach Anweisungen des Herstellers. </li><li> Messung der Höhe der CYP-Aktivität und normiert auf die Fläche (cm 2). </li></ol> 10. Immunfärbung <ol><li> Wasch hESC abgeleitet Hepatozyten mit PBS für 1 min, zwei Mal wiederholen. </li><li> Fügen eiskalten 100% Methanol, um Zellen zu fixieren, in -20 ° C für 10 min. </li><li> Waschen Sie die Zellen mit PBS für 5 min und zweimal wiederholen. </li><li> Inkubiere die Zellen mit PBS / T (0,1% Tween) / 10% BSA für 1 h bei RT. </li><li> Saugen Sie das PBST-Lösung und fügen Sie den entsprechenden primären Antikörpers in PBS / T (0,1% Tween) / 1% BSA verdünnt, Inkubation bei 4 ° C unter leichtem Schütteln O / N. </li><li> Waschen Sie die Zellen mit PBS / T (0,1% Tween) / 1% BSA für 5 min und dreimal wiederholen. </li><li> Verdünne die entsprechenden Antikörper in PBS / T (0,1% Tween) / 1% BSA, in den Zellen und Inkubation im Dunkeln bei Raumtemperatur 1 Stunde unter leichtem Schütteln. </li><li> Waschen Sie die Zellen mit PBS für 5 min und dreimal wiederholen. </li><li> Fügen MOWIOL 488 (mit DAPI 1: 1.000) in jede Vertiefung, fügen Sie ein Deckglas vorsichtig auf die Anzahl der Luftblasen zu reduzieren. Speicher fixierten Zellen bei 4 ° C im Dunkeln. Beachten Färbung unter Verwendung eines Mikroskops mit entsprechenden Filter und Leuchtstofflampen. Die optimierten primären und sekundären Antikörper sind in Tabelle 1 aufgelistet. </li></ol>

<ol>
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O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=UV+and+gamma+irradiation+effects+on+surface+properties+of+polyurethane+derivate+from+castor+oil.">UV and gamma irradiation effects on surface properties of polyurethane derivate from castor oil.</a> Pol&#237;meros. 23 (3), 305-311 (2013).</li><li>Rosu, L., Cascaval, C. N., Ciobanu, C., Rosu, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+UV+radiation+on+the+semi-interpenetrating+polymer+networks+based+on+polyurethane+and+epoxy+maleate+of+bisphenol+A.">Effect of UV radiation on the semi-interpenetrating polymer networks based on polyurethane and epoxy maleate of bisphenol A.</a> Journal of Photochemistry and Photobilogy A: Chemistry. 169 (2), 177-185 (2005).</li><li>Yang, X. F., Tallman, D. E., Bierwagen, G. P., Croll, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blistering+and+degradation+of+polyurethane+coatings+under+different+accelerated+weathering+tests.">Blistering and degradation of polyurethane coatings under different accelerated weathering tests.</a> Polymer Degradation and Stability. 77 (1), 103-109 (2002).</li></ol>

DCH ist CSO, Regisseur, Gründer und Gesellschafter der FibromEd Products Ltd MB und JPI sind Gründungsaktionäre in FibromEd Products Ltd

Viele der verwendeten Hepatozyten aus Stammzellen erzeugen aktuellen Methoden beruhen auf undefinierte Matrizen tierischen Ursprungs. Diese Substrate können kostspielig und sehr variabel sein und somit die Zellfunktion und der Stabilität, die ein großes Hindernis für Anwendung. Daher führten wir einen Bildschirm für synthetische Materialien, die die Kultur der Stammzell abgeleitet Hepatozyten zu unterstützen. Wir haben festgestellt, eine einfache Polyurethan (PU134) durch Polymerisation PHNGAD, MDI und ein Streck...

Biologische Materialien sind weit verbreitet bei der Aufrechterhaltung und Differenzierung von pluripotenten Stammzellen 1 verwendet. Und ermöglichen, enthalten diese biologischen Substraten oft eine Vielzahl von unbestimmten Komponenten. Matrigel ist eine häufig verwendete Substrat für die Stammzellkultur und Differenzierung. Leider beeinflusst die variable Zusammensetzung der Zellfunktion und Phänotyp. Obwohl eine Vielzahl von alternativen, definierten biologischen Matrices wurden verwendet, 2-7, ihre tierischen Ursprungs oder schlechte Skalierbarkeit macht sie ungeeignete Kandidaten für die industrielle Fertigung. Daher ist die Identifizierung von synthetischen Alternativen, mit definierter Zusammensetzung und zuverlässige Leistung, sind wichtige Ziele in der Stammzellforschung. In einem Versuch, die Grenzen der undefinierten Zellkultursubstraten zu überwinden, sind interdisziplinäre Kooperationen zwischen Chemie und Biologie synthetischen Materialien mit der Fähigkeit, Zell-Phänotyp unterstützt identifiziert. SynthWDV-Substrate sind skalierbar, kostengünstig und kann in komplexe 3D-Strukturen hergestellt werden, imitiert die in vivo-Umgebung. Aufgrund dieser Eigenschaften synthetischen Substraten sind weit verbreitet zu unterstützen und zu fahren Differenzierung vieler Zelltypen 8-10. Erweiterte und Hochdurchsatz-Assays haben die schnelle Screening von synthetischen Materialien erleichtert, von großen Bibliotheken, und lieferte neuartige Materialien mit flexiblen Eigenschaften mit breiten Anwendungen in der biomedizinischen Forschung und Entwicklung 11-13. Verwendung von Hochdurchsatz-, Polymer-Mikroarray-Screening-Technologie, haben wir schnell eine einfache Polyurethan (PU134), geeignet für die Instandhaltung von menschlichen Stammzellen abgeleiteten Hepatozyten identifiziert. Dieses Polymer wurde zu überlegen Tieren stamm Substrate hinsichtlich Hepatozyten-Differenzierung und-Funktion 14-16 sein. Wir haben anschließend die Beschichtungsbedingungen, Topographie und Sterilisationsverfahren, Effekte zugreifen optimiertauf Polymer Leistung bei der Stabilisierung Hepatozyten Funktion und Lebensdauer. Dies hat erhebliche Auswirkungen in Bezug auf das Verständnis der Biologie Grundlagen der Hepatozyten für Zell-basierte Modellierung und Anwendungen der regenerativen Medizin. Die hier beschriebene Technologie ist ein Beispiel, wie die Oberfläche eines synthetischen Polymers kann optimiert werden, um Zell-Phänotyp zu bewahren. Wir glauben, dass die Kombination dieser Technologie mit einer effizienten serumfreien Hepatozyten Differenzierungsprotokoll hat das Potenzial, eine skalierbare Herstellung von Hepatozyten zur Verwendung in in vitro-Modellierung und regenerative Medizin bereitzustellen.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Synthesis, preparation, coating and characterization of polymer PU134 coated coverslips</td>
		</tr>
		<tr>
			<td>Shaker</td>
			<td>Edmun B&#252;hler</td>
			<td>KS-15</td>
			<td></td>
		</tr>
		<tr>
			<td>Irradiator</td>
			<td>CIS Biointernational</td>
			<td>IBL 637&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin coater</td>
			<td>Specialty Coating System</td>
			<td>&#160;P-6708</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning Electron Microscope&#160;</td>
			<td>Philips</td>
			<td>XL30CPSEM</td>
			<td></td>
		</tr>
		<tr>
			<td>Atomic Force Microscope</td>
			<td>DimensionV Nanoscope, VEECO</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>p4-GLO CYP3A4</td>
			<td>Promega</td>
			<td>V8902</td>
			<td></td>
		</tr>
		<tr>
			<td>UV bulb</td>
			<td>ESCO</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NanoScope analysis software</td>
			<td>VEECO</td>
			<td></td>
			<td>version 1.20</td>
		</tr>
		<tr>
			<td>Fluorescence microscope</td>
			<td>Olympus</td>
			<td>TH45200</td>
			<td>Use Volocity 4 Software</td>
		</tr>
		<tr>
			<td>Tissue culture plates</td>
			<td>Corning, UK&#160;</td>
			<td>3527</td>
			<td></td>
		</tr>
		<tr>
			<td>glass slides</td>
			<td>Scientific Laboratory Supplies</td>
			<td>MIC3308</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethylene glycol</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>93171</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;1,6-hexanediol</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>240117</td>
			<td></td>
		</tr>
		<tr>
			<td>Neopentyl glycol</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>408255</td>
			<td></td>
		</tr>
		<tr>
			<td>Adipic acid</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>9582</td>
			<td></td>
		</tr>
		<tr>
			<td>anhydrous N,N-Dimethylformamide</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>227056</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethyl ether</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>676845</td>
			<td></td>
		</tr>
		<tr>
			<td>titanium (IV) butoxide&#160;</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>244112</td>
			<td></td>
		</tr>
		<tr>
			<td>1,4-butanediol&#160;</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>493732</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum oven</td>
			<td>Thermoscientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4,4&#8217;-Methylenebis(phenyl isocyanate)</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>101688</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrahydrofurane</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>401757</td>
			<td></td>
		</tr>
		<tr>
			<td>Sputter coater</td>
			<td>Bal-Tec SCD 050</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Inmunostaining</td>
		</tr>
		<tr>
			<td>Phosphate buffer saline (-MgCl2, -CaCl2)</td>
			<td>Gibco</td>
			<td>10010031</td>
			<td>&#160;Store at room temperature</td>
		</tr>
		<tr>
			<td>PBST, PBS made up with 0.1% TWEEN 20&#160;</td>
			<td>&#160; Scientific Laboratory Supplies Ltd</td>
			<td>EC607&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>&#160; Scientific Laboratory Supplies Ltd</td>
			<td>CHE5010</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma-Aldrich, UK</td>
			<td>A7906</td>
			<td></td>
		</tr>
		<tr>
			<td>MOWIOL 488 DAPI</td>
			<td>Calbiochem</td>
			<td>475904</td>
			<td>Made up in Tris HCL and glycerol as per manufacturers instructions</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Cell culture and Functional assay</td>
		</tr>
		<tr>
			<td>CYP3A activity pGLO kit</td>
			<td>Promega</td>
			<td>V8902</td>
			<td></td>
		</tr>
		<tr>
			<td>Hepatozyme</td>
			<td>Gibco</td>
			<td>17705021</td>
			<td></td>
		</tr>
		<tr>
			<td>TryLE express</td>
			<td>Life Technologies</td>
			<td><a href="http://www.lifetechnologies.com/order/catalog/product/12604013">12604013</a></td>
			<td></td>
		</tr>
	</tbody>
</table>

stabilizing hepatocellular phenotype using optimized synthetic surfaces

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing and maintaining primary and pluripotent stem cell derived hepatocytes. While biological matrices are useful, they permit short term culture of hepatocytes, limiting their widespread application. We have attempted to overcome the limitations using a synthetic polymer coating. Polymers represent one of the broadest classes of biomaterials and possess a wide range of mechanical, physical and chemical properties, which can be fine-tuned for purpose. Importantly, such materials can be scaled to quality assured standards and display batch-to-batch consistency. This is essential if cells are to be expanded for high through-put screening in the pharmaceutical testing industry or for cellular based therapy. Polyurethanes (PUs) are one group of materials that have shown promise in cell culture. Our recent progress in optimizing a polyurethane coated surface, for long-term culture of human hepatocytes displaying stable phenotype, is presented and discussed.

Polymerlösungsmittel beeinflusst die Topographie des mit Polymer beschichteten Oberfläche Polyurethan-134 wurde in Chloroform gelöst, entweder allein oder in Kombination mit Toluol oder Tetrahydrofuran oder Dichlormethan, und die Objektträger aus Glas mit den verschiedenen Formulierungen schleudert. Rasterelektronenmikroskopie (SEM) und Rasterkraftmikroskopie (AFM) wurden zur Charakterisierung der physikalischen Eigenschaften der Polymerschichten (Abbildung 1).</...

Watch this Scientific Journal Video about Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces at JoVE.com

Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces

Dieser Artikel wird auf die Entwicklung von Polymer-beschichteten Oberflächen für die langfristige Ausrichtung, stabile Kultur der Stammzell abgeleitet humanen Hepatozyten.

Stabilisierung Leberzell Phänotyp mit optimierten Surfaces

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing ...

stabilizing-hepatocellular-phenotype-using-optimized-synthetic

Research

JoVE Journal

Chemistry

10.2K Aufrufe.  University of Edinburgh.  Dieser Artikel wird auf die Entwicklung von Polymer-beschichteten Oberflächen für die langfristige Ausrichtung, stabile Kultur der Stammzell abgeleitet humanen Hepatozyten. 

Serie: Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces

Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell differentiation into osteoblasts, thus stimulating healing and de novo bone formation. The clinical use of recombinant human BMP-2 (rhBMP-2) in conjunction with scaffolds has raised recent controversies, based on the mode of presentation and the amount to be delivered. The protocol presented here provides a simple and efficient way to deliver BMP-2 for in vitro studies on cells. We describe how to form a self-assembled monolayer consisting of a heterobifunctional linker, and show the subsequent binding step to obtain covalent immobilization of rhBMP-2. With this approach it is possible to achieve a sustained presentation of BMP-2 while maintaining the biological activity of the protein. In fact, the surface immobilization of BMP-2 allows targeted investigations by preventing unspecific adsorption, while reducing the amount of growth factor and, most notably, hindering uncontrolled release from the surface. Both short- and long-term signaling events triggered by BMP-2 are taking place when cells are exposed to surfaces presenting covalently immobilized rhBMP-2, making this approach suitable for in vitro studies on cell responses to BMP-2 stimulation.

We describe a method for accomplishing efficient immobilization of BMP-2 on surfaces. Our approach is based on the formation of a self-assembled monolayer to achieve the covalent binding of BMP-2 via its free amine residues. This method is a useful tool to study signaling at the cell membrane.

Die kovalente Bindung von BMP-2 auf Oberflächen mit einem selbstorganisierten Monoschicht-Ansatz

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell ...

Forschung

Chemie

Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and lignin. Layer-by-layer (LbL) assembly process which relies on the assembly of oppositely charged molecules from aqueous solutions was used to build a freestanding composite film of isolated wood polymers of lignin and oxidized nanofibril cellulose (NFC). To facilitate the assembly of these negatively charged polymers, a positively charged polyelectrolyte, poly(diallyldimethylammomium chloride) (PDDA), was used as a linking layer to create this simplified model cell wall. The layered adsorption process was studied quantitatively using quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. The results showed that layer mass/thickness per adsorbed layer increased as a function of total number of layers. The surface coverage of the adsorbed layers was studied with atomic force microscopy (AFM). Complete coverage of the surface with lignin in all the deposition cycles was found for the system, however, surface coverage by NFC increased with the number of layers. The adsorption process was carried out for 250 cycles (500 bilayers) on a cellulose acetate (CA) substrate. Transparent free-standing LBL assembled nanocomposite films were obtained when the CA substrate was later dissolved in acetone. Scanning electron microscopy (SEM) of the fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle (PDDA-Lignin-PDDA-NC) was estimated to be 17 nm for two different lignin types used in the study. The data indicates a film with highly controlled architecture where nanocellulose and lignin are spatially deposited on the nanoscale (a polymer-polymer nanocomposites), similar to what is observed in the native cell wall.

The objective of this research was to form synthetic plant cell wall tissue using layer-by-layer assembly of nanocellulose fibrils and isolated lignin assembled from dilute aqueous suspensions.&#160; Surface measurement techniques of quartz crystal microbalance and atomic force microscopy were used to monitor the formation of the polymer-polymer nanocomposite material.

Gegen biomimetischen Holz: Hergestellt Freistehende Filme aus Nanocellulose, Lignin und eines synthetischen Polykation

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and ...

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of novel materials. Coupled with analysis by in situ secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS), soft landing provides unprecedented insights into the interactions of well-defined species with surfaces.

In-situ-SIMS und IR-Spektroskopie von gut definierten Oberflächen durch weiche Landung der Messe-Ionen ausgewählt Vorbereitet

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using ...

Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. The most common techniques utilized are imaging modalities such as Magnetic Resonance Imaging (MRI), Positron Emission Topography (PET), and Computed Topography (CT) and are optimal for understanding the physical structure of the disease but can only be performed once every four to six weeks due to the use of imaging agents and overall cost. With this in mind, the development of &#8220;point of care&#8221; techniques, such as biosensors, which evaluate the stage of disease and/or efficacy of treatment in the clinician&#8217;s office and do so in a timely manner, would revolutionize treatment protocols.1 As a means to exploring ferrocene based biosensors for the detection of biologically relevant molecules2, methods were developed to produce ferrocene-biotin bio-conjugates described herein. This report will focus on a biotin-ferrocene-cysteine system that can be immobilized on a gold surface.

The synthesis of asymmetric species of ferrocene is challenging using solution techniques. This report focuses on the methods carried out to produce a ferrocene-biotin bioconjugate using facile and clean reactions accomplished via solid-phase synthesis. Incorporation of a thiolate moiety is shown to impart the ability for immobilization on gold surfaces.

Synthesemethoden für Asymmetric Ferrocen abgeleitete Bio-Konjugat-Systemen über Festphasen-Resin-basierte Methodik

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. ...

Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional units (e.g., domains). Traditional consensus-building models fail to account for interpositional dependencies &#8211; functionally required covariation of residues that tend to appear simultaneously throughout evolution and across the phylogentic tree. These relationships can reveal important clues about the processes of protein folding, thermostability, and the formation of functional sites, which in turn can be used to inform the engineering of synthetic proteins. Unfortunately, these relationships essentially form sub-motifs which cannot be predicted by simple &#8220;majority rule&#8221; or even HMM-based consensus models, and the result can be a biologically invalid &#8220;consensus&#8221; which is not only never seen in nature but is less viable than any extant protein. We have developed a visual analytics tool, StickWRLD, which creates an interactive 3D representation of a protein alignment and clearly displays covarying residues. The user has the ability to pan and zoom, as well as dynamically change the statistical threshold underlying the identification of covariants. StickWRLD has previously been successfully used to identify functionally-required covarying residues in proteins such as Adenylate Kinase and in DNA sequences such as endonuclease target sites.

Synthetic protein sequences based on consensus motifs typically ignore co-evolving residues, that imply interpositional dependencies (IPDs). IPDs can be essential to activity, and designs that disregard them may result in suboptimal results. This protocol uses StickWRLD to identify IPDs and help inform rational protein design, resulting in more efficient results.

Optimierung der synthetische Proteine: Bezeichnung interpositional Abhängigkeiten Anzeige- strukturell und / oder funktionell verknüpft Rückstände

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional ...

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [125I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125I-labeled azide (1) was obtained with high radiochemical yield (75 &plusmn; 10%, n = 8) and excellent radiochemical purity (&gt;99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

A detailed procedure for the synthesis of a 125I-labeled azide and the radiolabeling of dibenzocyclooctyne (DBCO)-group-conjugated, 13-nm-sized gold nanoparticles using a copper-free click reaction is described.

Ein optimiertes Protokoll für die effiziente radioaktive Markierung von Gold-Nanopartikeln durch eine Verwendung von<sup&gt; 125</sup&gt; I-markiertem Azide prosthetische Gruppe

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient ...

Color Spot Test As a Presumptive Tool for the Rapid Detection of Synthetic Cathinones

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and other border protection agencies globally. Color testing is a presumptive identification technique indicating the presence or absence of a particular drug class using rapid and uncomplicated chemical methods. Owing to their relatively recent emergence, a color test for the specific identification of synthetic cathinones is not currently available. In this study, we introduce a protocol for the presumptive identification of synthetic cathinones, employing three aqueous reagent solutions: copper(II) nitrate, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and sodium acetate. Small pin-head sized amounts (approximately 0.1-0.2 mg) of the suspected drugs are added to the wells of a porcelain spot plate, and each reagent is then added dropwise sequentially before heating on a hotplate. A color change from very light blue to yellow-orange after 10 min indicates the likely presence of synthetic cathinones. The highly stable and specific test reagent has the potential for use in the presumptive screening of unknown samples for synthetic cathinones in a forensic laboratory. However, the nuisance of an added heating step for the color change result limits the test to laboratory application and decreases the likelihood of an easy translation to field testing.

Here we present a simple, inexpensive, and selective chemical spot test protocol for the detection of synthetic cathinones, a class of new psychoactive substances. The protocol is suitable for use in various areas of law enforcement that encounter illicit material.

Vor Ort Farbtest als mutmaßlichen Werkzeug für die schnelle Erkennung von synthetischen Cathinone

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and ...

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) Mass Spectrometry

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group analysis as matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). This tutorial demonstrates methods for optimization of the sample preparation, spectral acquisition, and data analysis of synthetic polymers using MALDI-TOF MS. Critical parameters during sample preparation include the selection of the matrix, identification of an appropriate cationization salt, and tuning the relative proportions of the matrix, cation, and analyte. The acquisition parameters, such as mode (linear or reflector), polarization (positive or negative), acceleration voltage, and delay time, are also important. Given some knowledge of the chemistry involved to synthesize the polymer and optimizing both the data acquisition parameters and the sample preparation conditions, spectra should be obtained with sufficient resolution and mass accuracy to enable the unambiguous determination of the end groups of most homopolymers (masses below 10,000) in addition to the repeat unit mass and the overall molecular weight distribution. Though demonstrated on a limited set of polymers, these general techniques are applicable to a much wider range of synthetic polymers for determining mass distributions, though end group determination is only possible for homopolymers with narrow dispersity.

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

A protocol for the matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) characterization of synthetic polymers is described including the optimization of sample preparation, spectral acquisition, and data analysis.

Charakterisierung von synthetischen Polymeren Matrix Assisted Laser Desorption Ionisation Zeit der Massenspektrometrie Flug (MALDI-TOF)

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group ...

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces are demonstrated. This work requires careful design, considerable synthetic effort, and proper analysis. The rotary motion of the molecular motor in solution is shown by 1H NMR and UV-vis absorption spectroscopy techniques. In addition, the method to graft the motor onto an amine-coated quartz is described. This method helps to gain more insight into molecular machines.

The manuscript describes how to synthesize and graft a molecular motor on surfaces for single molecular imaging.

Lichtgetriebenen molekularen Motoren auf Oberflächen für einzelne molekulare Bildgebung

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces ...

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

Ein Facile synthetische Methode, Wismut Oxyiodide Mikrosphären hochfunktionelle der photokatalytischen Prozesse der Wasser Depuration zu erhalten

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...