Questo lavoro è stato supportato da finanziamenti erogati dal Office of Naval Research. J. Fontana riconosce il Consiglio Nazionale delle Ricerche per una Associateship post-dottorato.

1. Self-assemblati Ligand-nanoparticelle Monolayers Come esempio illustrativo della tecnica di auto-assemblaggio, macroscopici, capped film monostrato oro nanosfere tiolo-alcano vengono prodotti come segue: <ol><li> Concentrato 15 nm nanosfere d&#39;oro (disponibili in commercio con una densità numero: 10 12 particelle / ml) a ~ 10 13 particelle / ml in acqua. <ol><li> Mettere 15 ml di sospensione acquosa diluita nanosfere in un filtro centrifugo ultra (100 K nominale limite di peso molecolare). </li><li> Centrifugare il filtro / flacone a 4.500 xg per 2 minuti o fino a pochi ml rimangono nella camera di filtrazione. </li></ol></li><li> Risospendere il NanoSphere in circa 1 ml di acqua deionizzata (DI) tale che la concentrazione delle nanoparticelle è 10 13 particelle / ml. La sospensione è stabile per parecchie ore una volta risospeso in acqua deionizzata. <ol><li> Verificare la densità di numero e confermare le nanoparticelle haNon ve aggregati. Diluire la sospensione nanoparticelle concentrato di un fattore di 1:10 indietro alla concentrazione originale posizionandolo 0.150 ml della sospensione in una cuvetta (1 cm di cammino), e per questo aggiungere 1,35 ml di acqua deionizzata. </li><li> Posizionare la cuvetta in uno spettrometro e misurare lo spettro di assorbanza della sospensione e la sospensione originale. Confrontare la posizione di picco e la larghezza a metà altezza per garantire non si verifica aggregazione. L&#39;ampiezza dei picchi di assorbanza per entrambi i campioni dovrebbe essere approssimativamente la stessa, garantendo così il campione concentrato è più denso di un fattore 10. </li></ol></li><li> In una fiala pulita vetro 20 ml borosilicato separata aggiungere 1 ml di tetraidrofurano (THF). </li><li> Aggiungere i ligandi tiolo-alcano (ad esempio 5 ml di 1,6-hexanedithiol e 5 ml di 1-dodecantiolo) al THF e agitare la soluzione per mescolare uniformemente. Ligando abbastanza deve essere aggiunto a coprire almeno l&#39;intera superficie delle nanoparticelle sospese. Excess ligando aumenta la velocità e l&#39;efficienza della reazione. </li><li> In una cappa aspirante, versare il contenuto del flacone contenente le nanosfere d&#39;oro nel flaconcino di THF-ligandi. </li><li> Avvitare rapidamente sul coperchio e agitare energicamente il flaconcino per 15 sec. </li><li> Rimuovere il coperchio e impostare il flaconcino dalla cappa, la figura 1 (a). A seconda dei leganti utilizzati, dominii film oro nanoparticelle formano rapidamente all&#39;interfaccia aria-liquido, Figura 1 (c). I film inizieranno a tradurre i lati della fiala, Figura 1 (d). Quasi tutte le nanoparticelle sono ricoperti con tiolo-ligando, rimosso dalla sospensione, e trasportati ai lati del flacone entro 1 ora, Figura 1 (e). </li></ol> 2. Trasferimento dei monostrati su supporti rimovibili <ol><li> Per trasferire i film su vetro removibile e substrati di wafer di silicio: tagliare i substrati in un&#39;area di 12,5 millimetri x 25,4 millimetri con unpenna incisione / ruota. <ol><li> Substrati di vetro: pulire con un risciacquo acetone, seguito da un risciacquo alcol isopropilico, e infine un risciacquo con acqua deionizzata. Lasciare i substrati ad asciugare, passare alla sezione 2.2. </li><li> Silicon Wafer Supporti: in una cappa aspirante preparare la soluzione Piranha (3 parti di acido solforico concentrato a 1 parte del 30% di perossido di idrogeno, ATTENZIONE: ossidante, corrosivo). Mettere 15 ml di acido solforico in un 20 ml in vetro borosilicato flaconcino. Per questo aggiungere lentamente 5 ml di 30% di perossido di idrogeno. Non tappare la fiala. Usare cautela; la miscela è altamente esotermica. Vedi di riferimento per ulteriori informazioni sulla sicurezza 19. </li><li> Immergere delicatamente i substrati di wafer di silicio in soluzione Piranha per 30 minuti, rimuovere, sciacquare con acqua deionizzata e asciugare con azoto. </li><li> Come passaggio facoltativo, il flaconcino utilizzato per lo scambio nanoparticelle ligando e di auto-assemblaggio può essere salinizzata forzare tutte le nanoparticelle sul substrato di vetro o SILicon wafer al posto delle pareti della fiala di vetro, altrimenti procedere alla sezione 2.2. </li><li> Riempire il flacone di vetro con la soluzione piranha (ATTENZIONE: ossidante, corrosivo), fare riferimento alla sezione 2.1.2. </li><li> Lasciare riposare il flaconcino in ammollo per 30 min. Dopo 30 minuti risciacquare il flacone con acqua deionizzata. </li><li> Riempire flacone con 1% v / v di esametildisilazano in acetone e cap. </li><li> Lasciare che il flacone sigillato in ammollo per 24 ore, poi sciacquare con acqua deionizzata e asciugare con azoto. </li></ol></li><li> Prima (punto 1.6) agitando inserire il supporto nel flaconcino. Avvitare il coperchio e agitare. </li><li> Dopo agitazione togliere il coperchio e, utilizzando una pinzetta, posizionare il substrato quasi verticale contro la parete flaconcino. </li><li> Utilizzare una pipetta per rivestire la miscela di reazione sul substrato. La reazione termina quando il solvente organico evaporato o tutte le nanoparticelle sono stati rimossi dalla sospensione. </li></ol> 3. Monolayer Analysis <ol><li> Stimare l&#39;efficienza delle nanosfere del monostrato imballaggio rapidamente osservando la trasmissione e caratteristiche di riflessione del film. Illuminare il monostrato su substrati di vetro da dietro con una sorgente di luce bianca. Con una fonte di luce bianca, una pellicola colorata uniforme dovrebbe essere osservato per alta densità film nanoparticella monostrato in trasmissione e riflessione oro-come osservato in riflessione, Figura 2. </li><li> Utilizzare uno spettrometro (vedere la sezione 1.2.2) per quantificare lo spettro di assorbimento macroscopico da monostrati, figura 4. Normalizzare lo spettro di assorbimento con un vetrino pulito. Montare il film monostrato, su un substrato di vetro, nel percorso ottico dello spettrometro e raccogliere lo spettro di assorbanza. Nota: Il picco di assorbanza deve essere significativamente rosso-spostato diverse centinaia di nanometri a seconda del legante usato. Il fattore di qualità del picco di assorbanza deve essere paragonabile al valore sospensione diluita, ma solo leggermente broadened (Figura 4). Se il picco di assorbimento è molto ampio e non ben definito, allora i film monostrato sono probabilmente di scarsa qualità, procedere alla sezione 3.3 per un&#39;ulteriore caratterizzazione. </li><li> Esaminare l&#39;organizzazione nanoscopica delle nanosfere utilizzando microscopia elettronica a scansione (SEM) di monostrati trasferite su substrati di wafer di silicio (vedere la sezione 2.1.2) come mostrato in Figura 3. Se i film sono su substrati di vetro collegano nastro conduttivo ad un angolo della pellicola e macinato al piedistallo SEM per evitare cariche e permettere imaging. </li></ol> 4. Fase efficiente tecnica di trasferimento per organico solubile nanoparticelle <ol><li> Per utilizzare la tecnica come un mezzo efficace per funzionalizzare le nanoparticelle con tiolo-ligandi, decantare la soluzione rimanente dal fondo della fiala dopo la reazione è completa, sezione 1.7, e asciugare il materiale nella fiala sotto azoto. </li><li> Aggiungere un solvente organico (ad esempiocloroformio, toluene) per risospendere le nanoparticelle con quasi il 100% di trasferimento di fase di particelle e di recupero. </li><li> Ripetere sezione 1.2.1 per garantire le nanoparticelle non sono aggregate su risospensione nel solvente organico. Se il picco di assorbanza è bordo, relativo alla sospensione originale, sonicare il campione per 15 min per aiutare amalgamare il nanoparticelle, Figura 4. </li></ol>

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Questo protocollo descrive un singolo &#39;one-pot&#39; tecnica di auto-assemblaggio per creare film monostrato di nanoparticelle-ligando macroscopici utilizzando il trasferimento di fase, la separazione di fase e gradienti di tensione superficiale. Il vantaggio di questa tecnica è che combina tre processi di auto-assemblaggio in un unico processo a basso costo; da eliminare in modo rapido ed efficiente trasferimento delle nanoparticelle, assemblaggio delle particelle in monostrati all&#39;interfaccia aria-liquido e tr...

L&#39;auto-assemblaggio di film di nanoparticelle macroscopiche ha attirato grande attenzione per le loro proprietà uniche determinate dalla geometria e la composizione degli elementi 5 e può portare a una vasta gamma di applicazioni ottiche, elettroniche e chimiche 6-14. Per auto-assemblarsi film nanoparticelle metalliche ricoperte con leganti devono essere imballati in alta densità, monostrati. Tuttavia diversi problemi di montaggio devono essere affrontate per promuovere lo sviluppo di tali materiali. Primo, tensioattivo stabilizzato nanoparticelle metalliche sono tipicamente sintetizzati con metodi wet-chimica in sospensioni diluite 15. Per prevenire l&#39;aggregazione e per controllare la spaziatura interparticellare delle nanoparticelle nei film, le nanoparticelle devono essere ricoperto con conchiglie ligando. Dopo le nanoparticelle sono stati funzionalizzati con ligandi nanoparticelle tipicamente rimangono in sospensioni relativamente diluite. Una tecnica è quindi neEDED di auto-assemblare le nanoparticelle in macroscopici, ad alta densità, film monostrato 16, 17. Cheng et al. 18 fase trasferito nanotubi d&#39;oro con polistirolo tiolato in una sospensione tetraidrofurano-acqua. I nanotubi dove poi risospesi in cloroformio e una goccia è stato messo a un&#39;interfaccia aria-acqua ed evaporati lentamente, formando pellicole monostrato. Bigioni et al. Creato 17 monostrati macroscopiche di dodecantiolo innevate nanosfere d&#39;oro con eccesso di ligando e rapida evaporazione del solvente, ma le nanosfere doveva essere trasferita prima fase di auto-assemblaggio. Una volta formati i film monostrato che in genere devono essere trasportati su un substrato. Mayya et al. 3 nanosfere confinato in un all&#39;interfaccia acqua-toluene e trasferiti su supporti privi di template utilizzando gradienti di tensione superficiale. Analogamente, Johnson <em&gt; et al. 4 sospesi nanosfere d&#39;argento superiori ligando e poi tradotto le nanoparticelle le pareti della fiala usando gradienti di tensione superficiale tra due liquidi immiscibili. Mentre le tecniche di assemblaggio esistono per affrontare ciascuno di questi problemi la necessità di tecniche più efficaci è necessario per aiutare nello sviluppo della grande produzione di film di nanoparticelle. Qui mostriamo una tecnica semplice e robusta che unisce i tre problemi auto-assemblaggio di cui sopra in una singola tecnica &#39;one-pot&#39;, mostrato in Figura 1. A acqua miscibile solvente organico (ad esempio tetraidrofurano, solfossido dimeythl), viene utilizzato per primo modo rapido ed efficiente funzionalizzare tiolo-ligandi (es tiolo-alcano, tiolo-ene, tiolo-fenolo) sulle nanoparticelle (ad esempio nanosfere, nanotubi oro, ecc.) La miscela quindi pilota auto-assemblaggio di nanoparticelle in macroscopica, ad alta densità, Monolayer film all&#39;interfaccia aria-liquido mediante separazione di fase. Infine, film monostrato di nanoparticelle formano su substrati senza template utilizzando gradienti di tensione superficiale dall&#39;acqua / miscela di solventi organici, Figura 2 e Figura 3.

<table border="0" cellpadding="0" cellspacing="0" width="628">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">1-6 hexanedithiol</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">H12005-5G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">1-dodecanethiol</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">471364-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">20 ml liquid scintillation vials</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">Z253081-1PAK</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:224px;">acetone</td>
			<td style="width:97px;">Sigma</td>
			<td>650501-1L</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:224px;">amicon ultra-15 centrifugal filter&#160;</td>
			<td style="width:97px;">Millipore</td>
			<td style="width:140px;">100K</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">centrifuge</td>
			<td style="width:97px;">Sorvall&#160;</td>
			<td style="width:140px;">RC5B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">centrifuge&#160;</td>
			<td style="width:97px;">Eppendorf</td>
			<td style="width:140px;">5810R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">deionized water&#160;</td>
			<td style="width:97px;">in-house&#39;</td>
			<td style="width:140px;">N/A</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:224px;">glass slides</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">CLS294875X25-72EA</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:224px;">15 nm gold nanospheres</td>
			<td style="width:97px;">Ted Pella, Inc</td>
			<td style="width:140px;">15703-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">hexamethyldisilazane</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">52619-50ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">hydrogen peroxide (30%)</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">216763-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">scanning electron microscope</td>
			<td style="width:97px;">Carl Zeiss</td>
			<td style="width:140px;">Model 55</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">polished silicon wafer</td>
			<td style="width:97px;">Sun Edison</td>
			<td style="width:140px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">spectrometer</td>
			<td style="width:97px;">OceanOptics</td>
			<td style="width:140px;">USB4000-VIS-NIR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">sulfuric acid</td>
			<td style="width:97px;">Fisher</td>
			<td style="width:140px;">A300-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">tetrahydrofuran</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">401757-100ML</td>
			<td></td>
		</tr>
	</tbody>
</table>

a technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates

Questo protocollo descrive una tecnica di auto-assemblaggio per creare film monostrato macroscopici composti da ligando rivestite nanoparticelle 1, 2. La tecnica semplice, robusto e scalabile functionalizes efficiente nanoparticelle metalliche con tiolo-ligandi in una miscela acqua / solvente organico miscibile consentono il rapido innesto di gruppi tiolici sulla superficie delle nanoparticelle d&#39;oro. I leganti idrofobi sulle nanoparticelle poi rapidamente fase separano le nanoparticelle dalla sospensione acquosa basato e le confinano all&#39;interfaccia aria-liquido. Questo spinge le nanoparticelle ligando-capped a formare domini monostrato all&#39;interfaccia aria-liquido. L&#39;uso di solventi organici miscibili con acqua è importante in quanto permette il trasporto delle nanoparticelle dall&#39;interfaccia su substrati senza template. Il flusso è mediato da una tensione gradiente superficie 3, 4 e crea macroscopica, ad alta densità, monostrato nanoppellicole articolo-ligando. Questa tecnica di auto-assemblaggio può essere generalizzata per includere l&#39;uso di particelle di varia composizione, le dimensioni e la forma e può portare a un metodo di assemblaggio efficiente per produrre film a basso costo, macroscopici, ad alta densità, monostrato di nanoparticelle per applicazioni diffuse .

Figura 1 (a) mostra una sospensione di nanosfere oro, leganti tiolici-alcano, tetraidrofurano e acqua in un flacone di vetro immediatamente dopo la miscelazione. Uno schema delle tre principali fasi di auto-assemblaggio, trasferimento di fase, separazione di fase, e la tensione superficiale gradiente di trasporto della pellicola mediata è mostrata in Figura 1 (b) come una vista espansa all&#39;interfaccia aria-liquido vicino al lato del flaconcino. I gruppi...

Watch this Scientific Journal Video about A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates at JoVE.com

A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

Una tecnica semplice, robusta e scalabile di funzionalizzare e di auto-assemblarsi film monostrato di nanoparticelle-ligando macroscopici su substrati libero di modello è descritto in questo protocollo.

Una tecnica di funzionalizzare e Self-montare macroscopiche nanoparticelle-ligando monostrato Films su substrati privi di modello

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and ...

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Research

JoVE Journal

Chemistry

10.8K Views.  Naval Research Laboratory.  Una tecnica semplice, robusta e scalabile di funzionalizzare e di auto-assemblarsi film monostrato di nanoparticelle-ligando macroscopici su substrati libero di modello è descritto in questo protocollo. 

Video: A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

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.

Legame covalente di BMP-2 su superfici utilizzando un auto-assemblato Monolayer Approccio

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 ...

Ricerca

Chimica

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.

Verso Biomimicking Legno: Fabbricato Free-standing Films di Nanocellulose, lignina, e policatione sintetico

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

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Modelli atomicamente definiti per epitassiale crescita di ossido Complex Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

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.

Fabbricazione di ampia superficie Free-standing ultrasottili film polimerici

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

Preparation of Mica and Silicon Substrates for DNA Origami Analysis and Experimentation

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of these applications require interaction with and adhesion of DNA nanostructures to a substrate. Due to its atomically flat and easily cleaned nature, mica has been the substrate of choice for DNA origami experiments. However, the practical applications of mica are relatively limited compared to those of semiconductor substrates. For this reason, a straightforward, stable, and repeatable process for DNA origami adhesion on derivatized silicon oxide is presented here. To promote the adhesion of DNA nanostructures to silicon oxide surface, a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) is deposited from an aqueous solution that is compatible with many photoresists. The substrate must be cleaned of all organic and metal contaminants using Radio Corporation of America (RCA) cleaning processes and the native oxide layer must be etched to ensure a flat, functionalizable surface. Cleanrooms are equipped with facilities for silicon cleaning, however many components of DNA origami buffers and solutions are often not allowed in them due to contamination concerns. This manuscript describes the set-up and protocol for in-lab, small-scale silicon cleaning for researchers who do not have access to a cleanroom or would like to incorporate processes that could cause contamination of a cleanroom CMOS clean bench. Additionally, variables for regulating coverage are discussed and how to recognize and avoid common sample preparation problems is described.

Reproducible cleaning processes for substrates used in DNA origami research are described, including bench-top RCA cleaning and derivatization of silicon oxide. Protocols for surface preparation, DNA origami deposition, drying parameters, and simple experimental set-ups are illustrated.

Preparazione di Mica e Silicon substrati per il DNA Origami Analisi e sperimentazione

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of ...

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (&#964;&#945;) regimes relevant to the glass transition (&#964;&#945; &#62; 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (&#964;&#945; &#60;&#60; 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment.

Here, we present a protocol for cooling rate dependent ellipsometry experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glass for a variety of glassy materials.

Raffreddamento Vota dipendenti Misure ellissometria per determinare la dinamica dei Thin Films Glassy

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements ...

Deacetylation Assays to Unravel the Interplay between Sirtuins (SIRT2) and Specific Protein-substrates

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further supported by recent findings in high-resolution mass spectrometry based proteomics showing that many new proteins and sites within these proteins can be acetylated. However the identity of the enzymes regulating these proteins and sites is often unknown. Among these enzymes, sirtuins, which belong to the class III histone lysine deacetylases, have attracted great interest as enzymes regulating the acetylome under different physiological or pathophysiological conditions. Here we describe methods to link SIRT2, the cytoplasmic sirtuin, with its substrates including both in vitro and in vivo deacetylation assays. These assays can be applied in studies focused on other members of the sirtuin family to unravel the specific role of sirtuins and are necessary in order to establish the regulatory interplay of specific deacetylases with their substrates as a first step to better understand the role of protein acetylation. Furthermore, such assays can be used to distinguish functional acetylation sites on a protein from what may be non-regulatory acetylated lysines, as well as to examine the interplay between a deacetylase and its substrate in a physiological context.

Deacetylation Assays to Unravel the Interplay between Sirtuins SIRT2 and Specific Protein-substrates

This protocol describes the required steps to execute in vitro and in vivo deacetylation assays in order to establish the role of proteins as specific deacetylation substrates for sirtuins and further study the role of reversible - lysine acetylation as a post-translational modification.

Deacetilazione saggi di svelare l&#39;interazione tra sirtuine (SIRT2) e specifici Protein-substrati

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further ...

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. Compared to other analytical separation techniques, such as chromatography, CE is cheap, robust and effectively requires no sample preparation (for a number of complex natural matrices or polymeric samples). CE is fast and can be used to follow the evolution of mixtures in real time (e.g., chemical reaction kinetics), as the signals observed for the separated compounds are directly proportional to their quantity in solution.
Here, the efficiency of CE is demonstrated for monitoring the covalent grafting of peptides onto chitosan films for subsequent biomedical applications. Chitosan&#39;s antimicrobial and biocompatible properties make it an attractive material for biomedical applications such as cell growth substrates. Covalently grafting the peptide RGDS (arginine - glycine - aspartic acid - serine) onto the surface of chitosan films aims at improving cell attachment. Historically, chromatography and amino acid analysis have been used to provide a direct measurement of the amount of grafted peptide. However, the fast separation and absence of sample preparation provided by CE enables equally accurate yet real-time monitoring of the peptide grafting process. CE is able to separate and quantify the different components of the reaction mixture: the (non-grafted) peptide and the chemical coupling agents. In this way the use of CE results in improved films for downstream applications.
The chitosan films were characterized through solid-state NMR (nuclear magnetic resonance) spectroscopy. This technique is more time-consuming and cannot be applied in real time, but yields a direct measurement of the peptide and thus validates the CE technique.

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Elettroforesi capillare per monitorare Peptide innesto su Chitosano film in tempo reale

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

Deposizione di vapore reattiva di film polimerici coniugati su substrati arbitrari

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. However, poor surface morphologies and relatively high bandgap energies have limited their potential. Silver-bismuth-iodine (Ag-Bi-I) is a promising semiconductor for optoelectronic devices. Therefore, we demonstrate the fabrication of Ag-Bi-I ternary thin films using material solution processing. The resulting thin films exhibit controlled surface morphologies and optical bandgaps according to their thermal annealing temperatures. In addition, it has been reported that Ag-Bi-I ternary systems crystallize to AgBi2I7, Ag2BiI5, etc. according to the ratio of the precursor chemicals. The solution-processed AgBi2I7 thin films exhibit a cubic-phase crystal structure, dense, pinhole-free surface morphologies with grains ranging in size from 200 to 800 nm, and an indirect bandgap of 1.87 eV. The resultant AgBi2I7 thin films show good air stability and energy band diagrams, as well as surface morphologies and optical bandgaps suitable for lead-free and air-stable single-junction solar cells. Very recently, a solar cell with 4.3% power conversion efficiency was obtained by optimizing the Ag-Bi-I crystal compositions and solar cell device architectures.

Solution-Processed &quot;Silver-Bismuth-Iodine&quot; Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Herein, we present detailed protocols for solution-processed silver-bismuth-iodine (Ag-Bi-I) ternary semiconductor thin films fabricated on TiO2-coated transparent electrodes and their potential application as air-stable and lead-free optoelectronic devices.

Soluzione di elaborazione "Silver-bismuto-iodio" ternario pellicole sottili per assorbitori di piombo fotovoltaici

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. ...