Die vorliegende Arbeit wurde teilweise durch die IGF-Projekt &quot;S-Sieve&quot; (490 ZBG / 1) durch das BMWi und des BMBF-Projektes &quot;Aptasens&quot; (BMBF / DLR 01RB0805A) finanziert finanziert. Besonderen Dank an Tobias J. Günther für seine wertvolle Hilfe bei der AFM-Studien und um Erik V. Johnstone zum Lesen des Manuskripts als englischer Muttersprachler. Ferner würde der Autor dieses Papieres gerne Aline Ritter und Sabrina Gurlit (vom Institut für Ressourcenökologie zur Unterstützung bei der ICP-MS-Messungen) zu danken, Manja Vogel, Nancy Unger, Karen E. Viacava und die Gruppe Biotechnologie des Helmholtz-Institut Freiberg für Ressourcentechnologie.

Die Autoren haben nichts zu offenbaren.

In dieser Arbeit untersuchten die Bindung von Au auf S-Layer-Proteine ​​wurde unter Verwendung einer Kombination von verschiedenen analytischen Methoden untersucht. Insbesondere die Bindung von Au ist sehr attraktiv, nicht nur für die Wiedergewinnung von Au aus dem Bergbau, Wasser oder Prozesslösungen, sondern auch für die Konstruktion von Materialien, zB sensorischen Oberflächen. Für Studien der Wechselwirkung Au (Au (III) und Au (0) -NPs) mit suspendierten und umkristallisiert Monoschicht von SLP1, d...

Aufgrund der zunehmenden Verwendung von Gold für verschiedene Anwendungen wie Elektronik, Katalysatoren, Biosensoren oder medizinische Instrumente hat sich die Nachfrage des Edelmetalls in den letzten Jahren 6-9 gewachsen. Gold sowie viele andere wertvolle und Schwermetalle in die Umwelt über industrielle Abwässer in verdünnten Konzentrationen durch Bergbauaktivitäten freigesetzt, und Entsorgungs 7,8,10, obwohl die meisten Umweltkontamination durch schwere oder Edelmetalle ist ein fortlaufender Prozess vor allem durch technologische Aktivitäten verursacht. Dies führt zu einer erheblichen Störung der natürlichen Ökosysteme und könnte möglicherweise die menschliche Gesundheit gefährden 9. Die Kenntnis dieser negativen Ergebnisse fördert die Suche nach neuen Techniken, um Metalle aus kontaminierten Ökosystemen und Verbesserungen beim Recycling von Metallen aus industriellen Abwässern zu entfernen. Etablierte physikalisch-chemische Methoden wie Fällung oder Ionenaustausch sind nicht so effektiv, vor allem in der Hochly verdünnten Lösungen 7,8,11. Biosorption entweder mit lebenden oder toten Biomasse, ist eine attraktive Alternative für die Abwasserbehandlung 10,12. Die Verwendung solcher biologischer Materialien kann der Verbrauch von toxischen Chemikalien zu verringern. Viele Mikroorganismen beschrieben worden zu sammeln oder zu immobilisieren Metallen. Zum Beispiel Zellen der Lysinibacillus sphaericus (L. sphaericus) JG-A12 haben hohe Bindungskapazitäten für Edelmetalle, dargestellt beispielsweise Pd (II), Pt (II), Au (III) und anderen toxischen Metallen wie Pb (II) oder U (VI) 4,13, Zellen des Bacillus megaterium für Cr (VI) 14, Zellen von Saccharomyces cerevisiae für Pt (II) und Pd (II) 15 und Chlorella vulgäre zur Au (III) und U (VI) 16 , 17. Die Bindung von Metallen wie Au vorherigen (III), Pd (II) und Pt (II) wurde auch für Desulfovibrio desulfuricans 18 gemeldet und L. sphaericus JG-B53 19,20. Dennoch sind nicht all Mikroben binden große Mengen von Metallen und deren Anwendung als Sorptionsmaterial begrenzt 12,21. Weiterhin Metallbindungskapazität hängt von verschiedenen Parametern, beispielsweise Zell-Zusammensetzung, die verwendet Biokomponente oder Umwelt- und experimentellen Bedingungen (pH, Ionenstärke, Temperatur etc.). Das Studium der isolierten Zellwandfragmente 22,23, wie Membranlipiden, Peptidoglycan, Proteinen oder anderen Komponenten kann dabei die Metallbindungsverfahren komplexer aufgebaut ganzen Zellen 8,21 zu verstehen. Die Zellbestandteile in dieser Studie konzentrierte sich auf sind S-Layer-Proteine. S-Layer-Proteine ​​sind Teile der äußeren Zellhülle von vielen Bakterien und Archaebakterien, und sie machen etwa 15 bis 20% der Gesamtproteinmasse dieser Organismen. Wie die erste Schnittstelle für die Umwelt, diese Zell Verbindungen beeinflussen die Bakterien Sorptionseigenschaften 3. S-Schicht-Proteine ​​mit Molekulargewichten im Bereich von vierzigHunderte von kDa sind innerhalb der Zelle produziert, aber außerhalb montiert, wo sie in der Lage, Schichten auf den Lipidmembranen oder polymere Zellwandbestandteile bilden. Nach der Isolierung fast alle S-Layer-Proteine ​​die intrinsische Eigenschaft, sich spontan durch Selbstorganisation in Suspension, an Grenzflächen oder auf Oberflächen bilden ebene oder röhrenförmige Gebilde 3. Die Dicke der Proteinmonoschicht hängt von den Bakterien und ist in einem Bereich von 5 bis 25 nm 24. Im Allgemeinen können die gebildeten S-Layer-Protein-Strukturen eine schräge (P1 oder P2), quadratisch (p4) oder hexagonal (p3 oder P6) symmetrisch Gitterkonstanten von 2,5 bis 35 nm 3,24 haben. Die Gitterbildung scheint in vielen Fällen abhängig von zweiwertigen Kationen und hauptsächlich Ca 2+ 25,26, Raff, J. et al. S-Layer-basierte Nanokomposite für industrielle Anwendungen in Proteinbasis Engineered Nanostrukturen. (Hrsg Tijana Z. Grove &amp; Aitziber L. Cortajarena) (Springer, 2016 (eingereicht)). Dennoch ist die vollständige Reaktionskaskade des Monomers Faltung Monomer-Monomer-Wechselwirkung, die Bildung eines Gitters, und die Rolle, die aus unterschiedlichen Metallen, insbesondere zweiwertigen Kationen, wie Ca 2+ und Mg 2+, noch nicht vollständig verstanden. Die Gram-positive Stamm L. sphaericus JG-B53 27 (von Bacillus sphaericus, nachdem neue phylogenetische Einordnung umbenannt) wurde aus dem Uranbergbau Halde &quot;Haberland&quot; (Johanngeorgenstadt, Sachsen, Deutschland) 4,28,29 isoliert. Seine Funktions S-Layer-Protein (SLP1) einen quadratischen Gitter, ein Molekulargewicht von 116 kDa 30 und eine Dicke von ≈ 10 nm an lebenden Bakterienzellen 31. In früheren Studien wurde die in vitro Bildung einer geschlossenen und stabilen Proteinschicht mit einer Dicke von etwa 10 nm in weniger als 10 min 19 erreicht. Die verwandten Stammes L. sphaericus JG- angezeigtA12, auch ein Isolat aus dem &quot;Haberland&quot; Haufen, besitzt eine hohe Metallbindungskapazitäten und seiner isolierten S-Schicht-Protein hat eine hohe chemische und mechanische Stabilität und gute Sorptionsraten für Edelmetalle wie Au (III) gezeigt, Pt (II), und Pd (II) 4,32,33. Diese Bindung von Edelmetallen ist mehr oder weniger spezifisch für bestimmte Metalle und hängt von der Verfügbarkeit der funktionellen Gruppen auf der äußeren und inneren Proteinoberfläche des Polymers und die in ihren Poren, der Ionenstärke und dem pH-Wert. Relevante funktionelle Gruppen für die Metall-Wechselwirkung durch die Proteine ​​sind COOH-, NH 2 -, OH-, PO 4 -, SO 4 - und SO. Grundsätzlich Metallbindungskapazitäten eröffnen ein breites Spektrum von Anwendungen, Raff, J. et al. S-Layer-basierte Nanokomposite für industrielle Anwendungen in Proteinbasis Engineered Nanostrukturen. (Hrsg Tijana Z. Grove &amp; Aitziber L. Cortajarena) (Springer, 2016 (eingereicht)). zB als biosorptive Komponenten zur Entfernung oder Wiederherstellungvon gelösten toxischen oder wertvolle Metalle, Vorlagen für die Synthese oder definierte Abscheidung von regelmäßig strukturierten metallischen Nanopartikeln (NPs) für die Katalyse und andere Bio-engineered Materialien wie Bio-sensorischen Schichten 3,5,18,33. Regelmäßig angeordnet NP Arrays wie Au (0) -NPs könnte für große Anwendungen, die von der molekularen Elektronik und Biosensoren, Ultrahochdichte-Speichergeräte, und Katalysatoren für die CO-Oxidation 34-37 verwendet werden. Die Entwicklung solcher Anwendungen und intelligente Design dieser Materialien erfordert ein tieferes Verständnis der zugrundeliegenden Metallbindungsmechanismen. Eine Voraussetzung für die Entwicklung solcher Materialien auf biologischer Basis ist die zuverlässige Ausführung eines Schnittstellenschicht zwischen dem Biomolekül und der technische Oberfläche 38,39. Zum Beispiel Polyelektrolyte mit der Schicht-für-Schicht (LBL) Technik 40,41 zusammengebaut wurden als Zwischenschicht zur Rekristallisation von S-Layer-Proteine ​​39 verwendet wurden </sup&gt;. Eine solche Schnittstelle bietet eine relativ einfache Möglichkeit, die Proteinbeschichtung auf eine reproduzierbare und quantitative Weise auszuführen. Durch Durchführung verschiedener Experimente mit und ohne Modifikation mit Klebevermittler, ist es möglich, Aussagen über die Beschichtungs Kinetik, Schichtstabilität und die Interaktion von Metallen mit Biomolekülen 19,42, Raff, J. et al machen. S-Layer-basierte Nanokomposite für industrielle Anwendungen in Proteinbasis Engineered Nanostrukturen. (Hrsg Tijana Z. Grove &amp; Aitziber L. Cortajarena) (Springer, 2016 (eingereicht)). Jedoch ist die komplexen Mechanismen der Proteinadsorption und Protein-Oberflächen-Wechselwirkung nicht vollständig verstanden. Vor allem Informationen über Konformation, Muster Orientierung und Beschichtungsdichten fehlt noch. Quarzmikrowaage mit Verlustüberwachung (QCM-D) Technik hat sich die Aufmerksamkeit in den letzten Jahren als ein Werkzeug für die Untersuchung der Proteinadsorption, Beschichtungs Kinetik und Interaktion pro zogenProzesse auf der Nanometerskala 19,43-45. Diese Technik ermöglicht die detaillierte Erfassung der Masse Adsorption in Echtzeit und kann als Indikator für das Protein selbst Montage und die Kopplung der funktionellen Moleküle auf Proteingitter 19,20,42,46-48 verwendet werden. Darüber hinaus öffnen QCM-D-Messungen die Möglichkeit, Metallwechselwirkungsprozesse mit der proteinhaltigen Schicht unter natürlichen biologischen Bedingungen zu studieren. In einer neueren Studie der Wechselwirkung des S-Layer-Protein mit ausgewählten Metallen wie Eu (III), Au (III), Pd (II) und Pt (II) wurde mit der QCM-D 19,20 sucht. Die adsorbierte Proteinschicht kann als vereinfachtes Modell eines Zellwand von gram-positiven Bakterien dienen. Die Untersuchung dieses einzelne Komponente kann zu einem tieferen Verständnis der Metall-Wechselwirkung beitragen. Allerdings wissen nur QCM-D-Experimente nicht Aussagen in Bezug auf Oberflächenstrukturen und Einflüsse von Metallen, um Protein zu ermöglichen. Andere Techniken sind notwendig, um diese Informationen zu erhalten. Eine postung für Abbildungs ​​bio-Nanostrukturen und Gewinnung von Informationen über Struktureigenschaften ist die Rasterkraftmikroskopie (AFM). Das Ziel der vorliegenden Studie war es, die Sorption von Gold (Au (III) und Au (0) -NPs) bis S-Layer-Proteine ​​zu untersuchen, insbesondere SLP1 von L. sphaericus JG-B53. 5.0 Verwendung von ICP-MS und immobilisiert S-Schichten unter Verwendung von QCM-D - Experimente wurden mit suspendierten Proteine ​​auf Ansatzgröße in einem pH-Bereich von 2,0 durchgeführt. Zusätzlich wurde der Einfluß der Metallsalzlösung auf dem Gitter Stabilität mit anschließender AFM-Studien untersucht. Die Kombination dieser Techniken trägt zu einem besseren Verständnis der in-vitro-Metall-Interaktionsprozesse als Werkzeug für das Lernen mehr über Bindungsereignisse auf ganze Bakterienzellen in Bezug auf bestimmte Metall Affinitäten. Diese Erkenntnis ist nicht nur wichtig für die Entwicklung von anwendbaren Filtermaterialien zur Rückgewinnung von Metallen für den Umweltschutz und zur Erhaltung der WiederQuellen 49, sondern auch für die Entwicklung von hoch geordneten Arrays von metallischen Nanopartikeln für verschiedene technische Anwendungen.

<table border="0" cellpadding="0" cellspacing="0" width="849">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:293px;">equiment and software</td>
			<td style="width:219px;"></td>
			<td style="width:97px;"></td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="36">
			<td height="36" style="height:36px;width:293px;">Bioreactor, Steam In Place 70L Pilot System</td>
			<td style="width:219px;">Applikon Biotechnology, Netherlands</td>
			<td style="width:97px;">Z6X</td>
			<td style="width:241px;">Including dO2, pH sensors of Applikon Biotechnology and BioXpert software V2</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Noninvasive Biomass Monitor BugEye 2100</td>
			<td style="width:219px;">BugLab, Concord (CA), USA</td>
			<td style="width:97px;">Z9X</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Spectrometer Ultrospec 1000</td>
			<td style="width:219px;">Amersham Pharmacia Biotech, Great Britain</td>
			<td style="width:97px;">80-2109-10</td>
			<td style="width:241px;">Company now GE Healthcare Life Sciences</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">MiniStar micro centrifuge</td>
			<td style="width:219px;">VWR, Germany</td>
			<td style="width:97px;">521-2844</td>
			<td style="width:241px;">For centrifugation of cultivation samples</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Research system microscope BX-61</td>
			<td style="width:219px;">Olympus Germany LLC, Germany</td>
			<td style="width:97px;">037006</td>
			<td style="width:241px;">Microscope in combination with imaging software</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Cell^P (version 3.1)</td>
			<td style="width:219px;">Olympus Soft Imaging Solutions LLC, M&#252;nster, Germany</td>
			<td style="width:97px;">---</td>
			<td style="width:241px;">together with microscope</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Powerfuge Pilot Separation System Serie 9010-S</td>
			<td style="width:219px;">Carr Centritech, Florida, USA</td>
			<td style="width:97px;">9010PLT</td>
			<td style="width:241px;">For biomasse harvesting</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">T18 basic Ultra Turrax</td>
			<td style="width:219px;">IKA Labortechnik, Germany</td>
			<td style="width:97px;">431-2601</td>
			<td style="width:241px;">For flagella removal and sample homogenization</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Sorvall Evolution RC Superspeed Centrifuge</td>
			<td style="width:219px;">Thermo Fisher Scientific, USA</td>
			<td style="width:97px;">728411</td>
			<td style="width:241px;">Used within protein isolation</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Mobile high shear fluid processor, M-110EH-30 Pilot</td>
			<td style="width:219px;">Microfluidics, Massachusetts, USA</td>
			<td style="width:97px;">M110EH30K</td>
			<td style="width:241px;">Used for cell rupture</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Alpha 1-4 LSC Freeze dryer</td>
			<td style="width:219px;">Martin Christ Freeze dryers LLC, Osterode, Germany</td>
			<td>102041</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">UV-VIS spectrophotometry (NanoDrop 2000c)</td>
			<td style="width:219px;">Thermo Fisher Scientific, USA</td>
			<td style="width:97px;">91-ND-2000C-L</td>
			<td style="width:241px;">For determination of protein concentration</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Mini-PROTEAN vertical electrophoresis chamber</td>
			<td style="width:219px;">Bio-Rad Laboratories GmbH, Munich, Germany</td>
			<td style="width:97px;">165-3322</td>
			<td style="width:241px;">For SDS-PAGE</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">VersaDoc Imaging System 3000</td>
			<td style="width:219px;">Bio-Rad Laboratories GmbH, Munich, Germany</td>
			<td style="width:97px;">1708030</td>
			<td style="width:241px;">Used for imaging of SDS-PAGE gels</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">ICP-MS Elan 9000</td>
			<td style="width:219px;">PerkinElmer, Waltham (MA), USA</td>
			<td style="width:97px;">N8120536</td>
			<td style="width:241px;">For determination of metal concentration</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Zetasizer Nano ZS</td>
			<td style="width:219px;">Malvern Instruments, Worcestershire United Kingdom</td>
			<td style="width:97px;">ZEN3600</td>
			<td style="width:241px;">For determination of nanoparticle size</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Q-Sense E4 device&#160;</td>
			<td style="width:219px;">Q-Sense AB, Gothenburg, Sweden</td>
			<td rowspan="3" style="width:97px;">QS-E4</td>
			<td rowspan="3" style="width:241px;">ordered via LOT quantum design (software included with E4 platform)</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Q-Soft 401 (data recording)</td>
			<td style="width:219px;">Q-Sense AB, Gothenburg, Sweden</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Q-Tools 3 (data evaluation and modelling)</td>
			<td style="width:219px;">Q-Sense AB, Gothenburg, Sweden</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">QCM-D flow modules QFM&#160;401&#160;</td>
			<td style="width:219px;">Q-Sense AB, Gothenburg, Sweden</td>
			<td style="width:97px;">QS-QFM401</td>
			<td style="width:241px;">ordered via LOT quantum design</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:293px;">QSX&#160;303 SiO2 piezoelectric AT-cut quartz sensors</td>
			<td style="width:219px;">Q-Sense AB, Gothenburg, Sweden</td>
			<td style="width:97px;">QS-QSX303</td>
			<td style="width:241px;">ordered via LOT quantum design</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Ozone cleaning chamber</td>
			<td style="width:219px;">Bioforce Nanoscience, Ames (IA), USA</td>
			<td style="width:97px;">QS-ESA006</td>
			<td style="width:241px;">ordered via LOT quantum design</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Atomic Force Microscope MFP-3D Bio AFM</td>
			<td style="width:219px;">Asylum Research, Santa Barbara (CA), USA</td>
			<td>MFP-3DBio</td>
			<td style="width:241px;">AFM measurements and imaging software</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Asylum Research AFM Software AR Version 120804+1223</td>
			<td style="width:219px;">Asylum Research, Santa Barbara (CA), USA</td>
			<td style="width:97px;">---</td>
			<td style="width:241px;">imaging software included in Cat. No. MFP-3DBio</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Igor Version Pro 6.3.2.3 Software</td>
			<td style="width:219px;">WaveMetrics, Inc., USA</td>
			<td style="width:97px;">---</td>
			<td style="width:241px;">imaging software included in Cat. No. MFP-3DBio</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">BioHeater</td>
			<td style="width:219px;">Asylum Research, Santa Barbara (CA), USA</td>
			<td style="width:97px;">Bioheater</td>
			<td style="width:241px;">Sample heater for AFM measurements</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Biolever mini cantilever,&#160; BL-AC40TS-C2</td>
			<td style="width:219px;">Olympus Germany LLC, Germany</td>
			<td style="width:97px;">&#160;BL-AC40TS-C2</td>
			<td style="width:241px;">Prefered cantilever for AFM measurements</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">WSxM 5.0 Develop 6.5 (2013)</td>
			<td style="width:219px;">Nanotec Electronica S.L. , Spain</td>
			<td style="width:97px;">freeware</td>
			<td style="width:241px;">Software for AFM analysis</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:293px;">Name</td>
			<td style="width:219px;">Company</td>
			<td style="width:97px;">Catalog Number</td>
			<td style="width:241px;">Comments</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:293px;">Detergents and other equiment</td>
			<td style="width:219px;"></td>
			<td style="width:97px;"></td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:293px;">Calcium chloride Dihydrate (CaCl2 &#8729; 2H2O)</td>
			<td style="width:219px;">Merck KGaA</td>
			<td style="width:97px;">1.02382</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="51">
			<td height="51" style="height:51px;width:293px;">acidic acid, 100 %, p.A.</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">3738.5</td>
			<td style="width:241px;">Danger, flammable and corrosive liquid and vapour. Causes severe skin burns and eye damage.</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Antifoam 204</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">A6426</td>
			<td style="width:241px;">For foam suppression</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">bromophenol blue, sodium salt</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">B5525</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:293px;">Coomassie Brilliant Blue R (C45H44N3NaO7S2)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">3862.1</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Deoxyribonuclease II from porcine spleen</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">D4138</td>
			<td style="width:241px;">Typ IV , 2,000-6,000&#160;Kunitz units/mg protein</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Ethanol, 95%</td>
			<td style="width:219px;">VWR, Germany</td>
			<td style="width:97px;">20827.467</td>
			<td style="width:241px;">Danger, flammable</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">glycerine, p.A.</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">3783.1</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:293px;">Gold(III) chloride trihydrate (HAuCl4 &#8729; 3H2O)</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">520918</td>
			<td style="width:241px;">Danger</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Guanidine hydrochloride (GuHCl)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">0037.1</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Hellmanex III</td>
			<td style="width:219px;">Hellma GmbH &#38; Co. KG</td>
			<td style="width:97px;">9-307-011-4-507</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:293px;">Hydrochloric acid (HCl) (37%)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">4625.2</td>
			<td style="width:241px;">Danger; Corrosive, used for pH adjustment</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Lysozyme from chicken egg white</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">L6876&#160;</td>
			<td style="width:241px;">Lyophilized powder, protein =90 %, =40,000 units/mg protein (Sigma)&#160;</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:293px;">Magnesium chloride Hexahydrate (MgCl2 &#8729; 6H2O)</td>
			<td style="width:219px;">Merck KGaA</td>
			<td style="width:97px;">1.05833</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Magnetic stirrer with heating,&#160; MR 3000K</td>
			<td style="width:219px;">Heidolph Instruments GmbH &#38; Co.KG, Germany</td>
			<td style="width:97px;">504.10100.00</td>
			<td style="width:241px;">Standard stirrer within experiment</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">NB-Media DM180</td>
			<td style="width:219px;">Mast Diagnostica GmbH</td>
			<td style="width:97px;">121800</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:293px;">Nitric acid (HNO3)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">HN50.1</td>
			<td style="width:241px;">Danger; Oxidizing, Corrosing</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">PageRuler Unstained Protein Ladder</td>
			<td style="width:219px;">ThermoScientific-Pierce</td>
			<td style="width:97px;">26614</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Poly(sodium 4-styrenesulfonat) (PSS)</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">243051</td>
			<td style="width:241px;">Average Mw ~70,000</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Polyethylenimine (PEI), branched</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">408727</td>
			<td style="width:241px;">Warning; Harmful, Irritant, Dangerous for the environment; average Mw ~25,000</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:293px;">Potassium carbonate anhydrous (K2CO3)</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">60108</td>
			<td style="width:241px;">Warning; Harmful</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Ribonuclease A from bovine pancreas&#160;</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">R5503</td>
			<td style="width:241px;">Type I-AS, 50-100 Kunitz units/mg protein&#160;</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Sodium azide (NaN3)</td>
			<td style="width:219px;">Merck KGaA</td>
			<td style="width:97px;">106688</td>
			<td style="width:241px;">Danger; very toxic and Dangerous for the environment</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Sodium chloride (NaCl)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">3957.2</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Sodium dodecyl sulfate (SDS)</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">L-5750</td>
			<td style="width:241px;">Danger; toxic</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Sodium hydroxide (NaOH)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">6771.1</td>
			<td style="width:241px;">Danger; Corrosive, used for pH regulation within cultivation and pH adjustment</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:293px;">Spectra/Por 6, Dialysis membrane, MWCO 50,000&#160;</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">1893.1</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Sulfuric acid (H2SO4)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">HN52.2</td>
			<td style="width:241px;">Danger; Corrosive, used for pH regulation within cultivation</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:293px;">Tannic acid (C76H52O46)</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">16201</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:293px;">TRIS HCl (C4H11NO3HCl)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">9090.2</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:293px;">Tri-sodium citrate dihydrate (C6H5Na3O7 &#8729; 2H2O)</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">3580.2</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:293px;">Triton X-100</td>
			<td style="width:219px;">CARL ROTH GmbH+CO.KG</td>
			<td style="width:97px;">3051.3</td>
			<td style="width:241px;">Warning; Harmful, Dangerous for the environment</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">VIVASPIN 500, 50.000 MWCO Ultrafiltration tubes</td>
			<td>Sartorius AG</td>
			<td>VS0132</td>
			<td style="width:241px;">---</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:293px;">&#946;-mercaptoethanol</td>
			<td style="width:219px;">Sigma-Aldrich Co. LLC.</td>
			<td style="width:97px;">M6250</td>
			<td style="width:241px;">Danger, toxic</td>
		</tr>
	</tbody>
</table>

au-interaction of slp1 polymers and monolayer from lysinibacillus sphaericus jg-b53 - qcm-d, icp-ms and afm as tools for biomolecule-metal studies

In this publication the gold sorption behavior of surface layer (S-layer) proteins (Slp1) of Lysinibacillus sphaericus JG-B53 is described. These biomolecules arrange in paracrystalline two-dimensional arrays on surfaces, bind metals, and are thus interesting for several biotechnical applications, such as biosorptive materials for the removal or recovery of different elements from the environment and industrial processes. The deposition of Au(0) nanoparticles on S-layers, either by S-layer directed synthesis 1 or adsorption of nanoparticles, opens new possibilities for diverse sensory applications. Although numerous studies have described the biosorptive properties of S-layers 2-5, a deeper understanding of protein-protein and protein-metal interaction still remains challenging. In the following study, inductively coupled mass spectrometry (ICP-MS) was used for the detection of metal sorption by suspended S-layers. This was correlated to measurements of quartz crystal microbalance with dissipation monitoring (QCM-D), which allows the online detection of proteinaceous monolayer formation and metal deposition, and thus, a more detailed understanding on metal binding.
The ICP-MS results indicated that the binding of Au(III) to the suspended S-layer polymers is pH dependent. The maximum binding of Au(III) was obtained at pH 4.0. The QCM-D investigations enabled the detection of Au(III) sorption as well as the deposition of Au(0)-NPs in real-time during the in situ experiments. Further, this method allowed studying the influence of metal binding on the protein lattice stability of Slp1. Structural properties and protein layer stability could be visualized directly after QCM-D experiment using atomic force microscopy (AFM). In conclusion, the combination of these different methods provides a deeper understanding of metal binding by bacterial S-layer proteins in suspension or as monolayers on either bacterial cells or recrystallized surfaces.

Kultivierung von Mikroorganismen und SLP1 Charakterisierung Die aufgezeichneten Daten des Bakterienwachstums zeigt das Ende der exponentiellen Wachstumsphase bei etwa 5 Stunden. Frühere Untersuchungen haben gezeigt, dass SLP1 können von diesem Zeitpunkt der Ernte (4,36 g / L nasser Biomasse (≈ 1,45 g / L (BDW)) mit einer maximalen Ausbeute 19 isoliert werden. Dennoch Optimierung der Kultivierung...

Watch this Scientific Journal Video about Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies at JoVE.com

Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies

To obtain basic information on the sorption and recycling of gold from aqueous systems the interaction of Au(III) and Au(0) nanoparticles on S-layer proteins were investigated. The sorption of protein polymers was investigated by ICP-MS and that of proteinaceous monolayers by QCM-D. Subsequent AFM enables the imaging of the nanostructures.

Au-Wechselwirkung von SLP1 Polymere und Monolayer aus<em&gt; Lysinibacillus sphaericus</em&gt; JG-B53 - QCM-D, ICP-MS und AFM als Werkzeuge für Biomolekül-Metallforschung

In this publication the gold sorption behavior of surface layer (S-layer) proteins (Slp1) of Lysinibacillus sphaericus JG-B53 is described. These ...

au-interaction-slp1-polymers-monolayer-from-lysinibacillus-sphaericus

Universidad San Sebastian

Research

JoVE Journal

Chemistry

Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies

11.3K Aufrufe.  Helmholtz-Zentrum Dresden-Rossendorf. To obtain basic information on the sorption and recycling of gold from aqueous systems the interaction of Au(III) and Au(0) nanoparticles on S-layer proteins were investigated. The sorption of protein polymers was investigated by ICP-MS and that of proteinaceous monolayers by QCM-D. Subsequent AFM enables the imaging of the nanostructures.

Serie: Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies

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

Manufacturing of Three-dimensionally Microstructured Nanocomposites through Microfluidic Infiltration

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite in&#64257;ltration of 3D interconnected microfluidic networks. The manufacturing of the reinforced beams begins with the fabrication of microfluidic networks, which involves layer-by-layer deposition of fugitive ink filaments using a dispensing robot, filling the empty space between filaments using a low viscosity resin, curing the resin and finally removing the ink.&#160;Self-supported 3D structures with other geometries and many layers (e.g.&#160;a few hundreds layers) could be built using this method. The resulting tubular micro&#64258;uidic networks are then infiltrated with thermosetting nanocomposite suspensions containing nanofillers (e.g.&#160;single-walled carbon nanotubes), and subsequently cured. The infiltration is done by applying a pressure gradient between two ends of the empty network (either by applying a vacuum or vacuum-assisted microinjection). Prior to the infiltration, the nanocomposite suspensions are prepared by dispersing nanofillers into polymer matrices using ultrasonication and three-roll mixing methods. The nanocomposites (i.e.&#160;materials infiltrated) are then solidified under UV exposure/heat cure, resulting in a 3D-reinforced composite structure. The technique presented here enables the design of functional nanocomposite macroscopic products for microengineering applications such as actuators and sensors.

Three-dimensional (3D) microstructured composite beams are fabricated through the directed and localized infiltration of nanocomposites into 3D porous microfluidic networks. The flexibility of this manufacturing method enables the utilization of different thermosetting materials and nanofillers in order to achieve a variety of functional 3D reinforced nanocomposite macroscopic products.

Herstellung von dreidimensional Mikrostrukturierte Nanokomposite durch Mikrofluidik-Infiltration

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite ...

Standards for Quantitative Metalloproteomic Analysis Using Size Exclusion ICP-MS

Metals are essential for protein function as cofactors to catalyze chemical reactions. Disruption of metal homeostasis is implicated in a number of diseases including Alzheimer's and Parkinson's disease, but the exact role these metals play is yet to be fully elucidated. Identification of metalloproteins encounters many challenges and difficulties. Here we report an approach that allows metalloproteins in complex samples to be quantified. This is achieved using size exclusion chromatography coupled with inductively coupled plasma - mass spectrometry (SEC-ICP-MS). Using six known metalloproteins, the size exclusion column can be calibrated and the respective trace elements (iron, copper, zinc, cobalt, iodine) can be used for quantification. SEC-ICP-MS traces of human brain and plasma are presented. The use of these metalloprotein standards provides the means to quantitatively compare metalloprotein abundances between biological samples. This technique is poised to help shed light on the role of metalloproteins in neurodegenerative disease as well as other diseases where imbalances in trace elements are implicated.

Size exclusion chromatography hyphenated with inductively coupled plasma - mass spectrometry (ICP-MS) is a powerful tool to measure changes in the abundance of metalloproteins directly from biological samples. Here we describe a set of metalloprotein standards used to estimate molecular mass and the amount of metal associated with unknown proteins.

Standards für die quantitative Metalloproteomic Analyse mit Größenausschluss-ICP-MS

Metals are essential for protein function as cofactors to catalyze chemical reactions. Disruption of metal homeostasis is implicated in a number of ...

HKUST-1 as a Heterogeneous Catalyst for the Synthesis of Vanillin

Vanillin (4-hydoxy-3-methoxybenzaldehyde) is the main component of the extract of vanilla bean. The natural vanilla scent is a mixture of approximately 200 different odorant compounds in addition to vanillin. The natural extraction of vanillin (from the orchid Vanilla planifolia, Vanilla tahitiensis and Vanilla pompon) represents only 1% of the worldwide production and since this process is expensive and very long, the rest of the production of vanillin is synthesized. Many biotechnological approaches can be used for the synthesis of vanillin from lignin, phenolic stilbenes, isoeugenol, eugenol, guaicol, etc., with the disadvantage of harming the environment since these processes use strong oxidizing agents and toxic solvents. Thus, eco-friendly alternatives on the production of vanillin are very desirable and thus, under current investigation. Porous coordination polymers (PCPs) are a new class of highly crystalline materials that recently have been used for catalysis. HKUST-1 (Cu3(BTC)2(H2O)3, BTC = 1,3,5-benzene-tricarboxylate) is a very well known PCP which has been extensively studied as a heterogeneous catalyst. Here, we report a synthetic strategy for the production of vanillin by the oxidation of trans-ferulic acid using HKUST-1 as a catalyst.

The conversion of trans-ferulic acid to vanillin was achieved by heterogeneous catalysis. HKUST-1 was employed in this synthesis and the essential step in the catalytic process was the generation of unsaturated metal sites. Thus, when the catalyst was activated under vacuum, full vanillin conversion (yield of 95%) was obtained.

HKUST-1 als heterogener Katalysator für die Synthese von Vanillin

Vanillin (4-hydoxy-3-methoxybenzaldehyde) is the main component of the extract of vanilla bean. The natural vanilla scent is a mixture of approximately ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Elektrochemische Impedanz Spektroskopie als Instrument zur elektrochemischen Rate Konstanten Schätzung

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule on the vibrational level of energy. Raman and IR spectroelectrochemistry can be used for advanced characterization of the structural changes in the organic electroactive compounds. Here, the step-by-step analysis by means of Raman and IR spectroelectrochemistry is shown. Raman and IR spectroelectrochemical techniques provide complementary information about structural changes occurring during an electrochemical process, i.e. allows for the investigation of redox processes and their products. The examples of IR and Raman spectroelectrochemical analysis are presented, in which the products of the redox reactions, both in solution and solid state, are identified.

A protocol of step-by-step Raman and IR spectroelectrochemical analysis is presented.

Raman und IR Spectroelectrochemical Methoden als Werkzeuge konjugierte organische Verbindungen zu analysieren

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule ...

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance (EPR) or ultraviolet-visible and near-infrared (UV-Vis-NIR) spectroscopies, we obtain useful information such as electron affinity, ionization potential, band-gap energies, the type of charge carriers, and degradation information that can be used to synthesize stable organic electronic devices. In this study, we present electrochemical and spectroelectrochemical methods to analyze the processes occurring in active layers of an organic device as well as the generated charge carriers.

In this article, we describe electrochemical, electron paramagnetic resonance, and ultraviolet-visible and near-infrared spectroelectrochemical methods to analyze organic compounds for application in organic electronics.

Mithilfe von zyklischer Voltammetrie, UV-Vis-NIR und EPR Spectroelectrochemistry organische Verbindungen analysieren

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance ...

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the aziridine ring. The utility of bicyclic aziridinium ions, specifically 1-azoniabicyclo[3.1.0]hexane and 1-azoniabicyclo[4.1.0]heptane tosylate highlighted in the aziridine ring openings by the nucleophile with the release of the ring strain to yield the corresponding ring-expanded azaheterocycles such as pyrrolidine, piperidine and azepane with diverse substituents on the ring in regio- and stereospecific manner. Herein, we report a simple and convenient method for the preparation of the stable 1-azabicyclo[4.1.0]heptane tosylate followed by selective ring opening via a nucleophilic attack either at the bridge or at the bridgehead carbon to yield piperidine and azepane rings, respectively. This synthetic strategy allowed us to prepare biologically active natural products containing piperidine and azepane motif including sedamine, allosedamine, fagomine and balanol in highly efficient manner.

Bicyclic aziridinium ions such as 1-azoniabicyclo[4.1.0]heptane tosylate were generated from 2-[4-tolenesulfonyloxybutyl]aziridine, which was utilized for the preparation of substituted piperidines and azepanes via regio- and stereospecific ring-expansion with various nucleophiles. This highly efficient protocol allowed us to prepare diverse azaheterocycles including natural products such as fagomine, febrifugine analogue and balanol.

Vorbereitung der stabile bicyclische Aziridinium Ionen und ihre Ring-Öffnung für die Synthese von Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the ...

Stereolithographic 3D Printing with Renewable Acrylates

The accessibility of cost-competitive renewable materials and their application in additive manufacturing is essential for an efficient biobased economy. We demonstrate the rapid prototyping of sustainable resins using a stereolithographic 3D printer. Resin formulation takes place by straightforward mixing of biobased acrylate monomers and oligomers with a photoinitiatior and optical absorber. Resin viscosity is controlled by the monomer to oligomer ratio and is determined as a function of shear rate by a rheometer with parallel plate geometry. A stereolithographic apparatus charged with the biobased resins is employed to produce complex shaped prototypes with high accuracy. The products require a post-treatment, including alcohol rinsing and UV irradiation, to ensure complete curing. The high feature resolution and excellent surface finishing of the prototypes is revealed by scanning electron microscopy.

A protocol for additive manufacturing with renewable photopolymer resins on a stereolithography apparatus is presented.

Köraform 3D-Druck mit erneuerbaren Acrylaten

The accessibility of cost-competitive renewable materials and their application in additive manufacturing is essential for an efficient biobased economy. ...

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic nanoparticles is developed. Guidelines for the replication of the reactor and its operation are provided in detail. Three different composite systems (Pt/graphene, Pt/TiO2, and Au/TiO2) with monodisperse and uniformly distributed particles are produced by this reactor, and the photodeposition mechanism, as well as the synthesis optimization strategy, are discussed. The synthesis methods and their technical aspects are described comprehensively. The role of the ultraviolet (UV) dose (in each excitation pulse) on the photodeposition process is investigated and the optimum values for each composite system are provided.

For a continuous and scalable synthesis of noble-metal-based nanocomposites, a novel photocatalytic reactor is developed and its structure, operation principles, and product quality optimization strategies are described.