Questo lavoro è stato supportato da NSF / DOE partenariato nel plasma Scienza e della Tecnologia (NSF Concessione n. cbet-0853777 e il DOE Concessione n ° DE-SC0001169), STTR Fase I del progetto (NSF STTR FASE I No.1010133). Gli autori desiderano ringraziare il Programma di Ricerca PPPL Offsite sostenuta dall&#39;Ufficio di Fusion Scienze Energia per supportare esperimenti arco.

1. Preparazione anodo <ol><li> Nichel in polvere scala (99,8%, 300 maglie) e ittrio in polvere (99,9%, 40 mesh) secondo la radio molare di 4,2:1 in polvere catalizzatore. </li><li> Miscelare la polvere catalizzatore con polvere di grafite (99,9995%, 200 mesh) molto bene. Riempire la polvere miscelato in asta di grafite cavo (5 mm di diametro esterno, 2,5 mm di diametro interno e 75 mm di lunghezza) con decisione. Assicurarsi che la radio totale molare di C: Ni: S in asta anodo è 94.8:4.2:1, che è il rapporto ottimale di sintetizzare SWCNT 9. </li><li> Installare catodo asta (grafite pura, 13 mm di diametro) e l&#39;asta anodo ripieno all&#39;interno della camera cilindrica (acciaio inox, 152 mm di diametro e 254 mm di lunghezza). Regolare la distanza divario tra catodo e anodo di circa 3 mm. </li></ol> 2. Substrato di setup <ol><li> Mettere un magnete permanente parallelepipedo (25 mm × 25 mm × 100 mm) all&#39;interno della camera di circa 25 mm di distanza dall&#39;asse interelettrodica. L&#39;Ultra-High-Temp Alnico magnete utilizzatonell&#39;esperimento ha il peso di 650 grammi. Utilizzare la configurazione quando il divario interelettrodica è posto alla distanza di circa h = 75 mm (Figura 1a) dal fondo del magnete permanente. </li><li> Tagliare il spessore 0,3 mm Scheda di molibdeno (99,95%) come la mm 25 × 100 mm forma rettangolare. Eliminare la contaminazione superficiale da dismembrator ultrasuoni in acetone ed etanolo per 30 minuti con ampiezza del 50% sonicating, 150 w di potenza e 40 kHz. </li><li> Installare foglio molibdeno allegando un lato del magnete permanente, e trasformare questo lato verso elettrodi. </li><li> Misurare il campo magnetico nel vuoto da un interelettrodica Gauss-metro. Tenere il campo magnetico media tra gli elettrodi è di circa 0,06 T. </li></ol> 3. Accensione del plasma <ol><li> Pompa lungo la camera cilindrica a pressione inferiore a 10 -1 Torr a vuoto e poi riempito con elio (99,995%) a 500 Torr. </li><li> Collegare gli elettrodi dell&#39;arco di CC welding alimentazione e impostare l&#39;alimentazione a corrente arco di circa 75 A. </li><li> Registra in tempo reale i valori di arco di corrente, tensione d&#39;arco e la pressione della camera di post-esperimento di analisi. </li><li> Avviare il video di un arco da finestre a destra e frontale da due macchine fotografiche digitali contemporaneamente. Le istantanee dopo 1 secondo d&#39;arco di partenza sono mostrati in figura 1b (dalla finestra di destra) e Figura 1d (vista da davanti). </li><li> Eseguire l&#39;arco per 15 secondi. Raffreddare camera per convezione naturale per almeno 20 minuti. </li></ol> 4. Post-sintesi l&#39;analisi e la caratterizzazione <ol><li> Utilizzare pinzette per strappare il fiocco deposizione dalla superficie del foglio molibdeno, dove era diretto il getto dell&#39;arco plasma. Un altro campione viene raccolto dal collare nero di catodo. Osservare la morfologia di entrambi i lati del fiocco di deposizione sotto SEM (tensione di accelerazione di 30 KV è stato utilizzato). </li><li> Per quanto riguarda la preparazione del campione per<html> TEM analisi, i film sottili di campione sono stati ottenuti a goccia colata una sospensione di metanolo-dispersi soluzione SWCNT dopo sonicating per 60 minuti usando dismembrator ad ultrasuoni con il 50% sonicating ampiezza. Osservare la morfologia del film sottile sotto JEOL TEM con la tensione di 100 KV dopo la volatilizzazione della soluzione di metanolo. Per la posizione di interesse nel campione, pattern di diffrazione di elettroni può essere ottenuto con la lunghezza camera CCD di 50 cm associati TEM. </li><li> Spettroscopia Raman è stata effettuata su un micro-Raman sistema basato su un 200 mW Lexel 3000 Ar laser a ioni (sintonizzabile uscita singola linea), con ottica olografica, spettrometro di 0,5 m ed una di azoto raffreddato a liquido rivelatore CCD; lunghezza d&#39;onda 514 nm, che corrisponde al energia di 2,33 eV. Misure Raman coperto la gamma da 100 cm -1 a 3100 cm -1, e sono state effettuate sulla superficie di fiocchi di grafene. </li></ol> 5. Rappresentante Risultati &quot;&gt; Le istantanee video ottenuto contemporaneamente da finestre a destra e davanti alla camera sono mostrati in figura 1b, d per h = 75 mm. Queste immagini illustrano significativa perturbazione della colonna d&#39;arco plasma in presenza di campo magnetico esterno in confronto con la colonna arco assialmente simmetrica osservato nel caso senza un campo magnetico 10. Figura 2a e 2b visualizzare la morfologia tipica delle particelle e catalizzatore SWCNT raccolte sul colletto del catodo senza campo magnetico e con il campo magnetico di B = 0,06 Tesla sotto TEM, rispettivamente. Si può notare che SWCNT con il campo magnetico sono vicini confezionati in fasci con diametri che vanno da 2 a 20 nm a causa delle interazioni di van der Waals tra SWCNT individuali. In confronto, il SWCNT senza campo magnetico hanno il diametro maggiore in fasci e diametro maggiore individuale, che è coerente con l&#39;analisi dello spettro Raman. Inoltre, il campo magnetico can risultato nel SWCNT con maggiore purezza mostrato in Figura 2a e 2b. L&#39;influenza più interessanti del campo magnetico è che fiocchi di grafene può essere ottenuto dalla superficie di fiocchi deposizione che è vicino al foglio di molibdeno nello stesso processo. Figura 2c e 2d mostrare le immagini al SEM e TEM di fiocchi di grafene così come pochi strato di grafene ottenuti dal campione prelevato presso la sede corrispondeva ad arco plasma getti. L&#39;inserto della figura 2d mostra il modello di diffrazione di elettroni associati con il grafene. La struttura esagonale punti di diffrazione di elettroni presenta l&#39;evidenza di ben ordinata strutture cristalline. Spettro Raman è un potente strumento per la caratterizzazione di fiocchi di grafene e SWCNT. I picchi tipici osservati in grafene sono le cime G e 2D a ~ 1600 cm -1 e ~ 2700 centimetri -1 rispettivamente, con la lunghezza d&#39;onda di eccitazione di 514 nm. Il Gdi picco deriva da vibrazioni in aereo, che può essere osservata in tutti i materiali di carbonio sp2. Il picco 2D è un secondo ordine del picco D, ma è visto anche non sistemi disordinati, per il quarto fonone processo di ordinazione slancio risonanza doppio scambio. Essa svolge un ruolo fondamentale nella caratterizzazione del grafene. L&#39;intensità I (2D) / I (G) è di circa 4 per grafene monostrato e diminuisce con l&#39;aggiunta di strati successivi, rendendo così possibile stimare lo spessore di strati di grafene. 11 Figura 3 indica che il valore di I (2D) / I (G) è di circa 1, che può essere l&#39;evidenza di alcuni strati di grafene. La modalità di respirazione radiale (RBM) tra 120 e 350 cm -1 a spettro Raman può essere utilizzato per identificare il diametro dei nanotubi attraverso la frequenza di vibrazione coerente degli atomi C in direzione radiale. La relazione sperimentale tra la frequenza e il diametro è SWCNT RBM ω = A / d t + B, dove i parametri of A e pari a 234 e 10 cm -1 B, rispettivamente, per il SWCNT tipica forma in fasci. Dalla Figura 3, le frequenze RBM di SWCNT senza e con il campo magnetico sono 163,8 e 215,2 centimetri -1, corrispondente al diametro medio di SWCNT individuale di 1,52 e 1,14 nm, rispettivamente. <img alt="Figura 1." src="/files/ftp_upload/3455/3455fig1.jpg" /> Figura 1. Distribuzione del campo magnetico simulato da FEMM 4,2 software (a), fotografia di getto dell&#39;arco plasma dalla finestra di destra (b), schema di posizione degli elettrodi e del campo magnetico in direzione del gap per il caso in cui il gap è posizionato interelettrodica circa 75 mm sopra il fondo del magnete permanente (c), e la fotografia di getto dell&#39;arco plasma dalla parte anteriore della vista (d). <img alt="Figura 2." src="/files/ftp_upload/3455/3455fig2.jpg" /> Figura 2. TEM immagine rappresentante di as-sintetizzateFasci SWCNT senza campo magnetico (a) e fasci SWCNT con il campo magnetico (b), tipica immagine SEM di fiocchi di grafene sintetizzato con il campo magnetico (c), e l&#39;immagine TEM di grafene con il campo magnetico. Inserto è la scelta dell&#39;area di diffrazione di elettroni schema mostra la struttura cristallina del grafene. <img alt="Figura 3." src="/files/ftp_upload/3455/3455fig3.jpg" /> Figura 3. Spettro Raman dei campioni con il campo magnetico nel range di 100-3100 cm -1. Inset: spettro Raman di campioni senza campo magnetico intorno frequenze RBM. <img alt="Figura 4." src="/files/ftp_upload/3455/3455fig4.jpg" /> Figura 4. Crescita regione nanostruttura e la densità numero di carbonio e nichel per l&#39;arco di 60 A. Si noti che la densità di carbonio e nichel visualizzato sul lato destro e sinistro degli elettrodi, coesistono nella stessa regione.

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	<li>Dai, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+transport+properties+and+field+effect+transistors+of+carbon+nanotubes.">Electrical transport properties and field effect transistors of carbon nanotubes.</a> Nano. 1, 1-13 (2006).</li><li>Lai, K. W. C., Xi, N., Fung, C. K. M., Chen, H. Z., Tarn, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+the+band+gap+of+carbon+nanotube+for+infrared+sensors.">Engineering the band gap of carbon nanotube for infrared sensors.</a> Applied Physics Letters. 95, 221107-221107 (2009).</li><li>Gabor, N. M., Zhong, Z. H., Bosnick, K., Park, J., McEuen, P. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extremely+Efficient+Multiple+Electron-Hole+Pair+Generation+in+Carbon+Nanotube+Photodiodes.">Extremely Efficient Multiple Electron-Hole Pair Generation in Carbon Nanotube Photodiodes.</a> Science. 325, 1367-1371 (2009).</li><li>Liu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+storage+in+single-walled+carbon+nanotubes+at+room+temperature.">Hydrogen storage in single-walled carbon nanotubes at room temperature.</a> Science. 286, 1127-1129 (1999).</li><li>Keidar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic-field-enhanced+synthesis+of+single-wall+carbon+nanotubes+in+arc+discharge.">Magnetic-field-enhanced synthesis of single-wall carbon nanotubes in arc discharge.</a> Journal of Applied Physics. 103, 094318-094318 (2008).</li><li>Li, J., Volotskova, O., Shashurin, A., Keidar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlling+Diameter+Distribution+of+Catalyst+Nanoparticles+in+Arc+Discharge.">Controlling Diameter Distribution of Catalyst Nanoparticles in Arc Discharge.</a> Journal of Nanoscience and Nanotechnology. 11, 10047-10052 (2011).</li><li>Volotskova, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tailored+Distribution+of+Single-Wall+Carbon+Nanotubes+from+Arc+Plasma+Synthesis+Using+Magnetic+Fields.">Tailored Distribution of Single-Wall Carbon Nanotubes from Arc Plasma Synthesis Using Magnetic Fields.</a> Acs. Nano. 4, 5187-5192 (2010).</li><li>Volotskova, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-step+synthesis+and+magnetic+separation+of+graphene+and+carbon+nanotubes+in+arc+discharge+plasmas.">Single-step synthesis and magnetic separation of graphene and carbon nanotubes in arc discharge plasmas.</a> Nanoscale. 2, 2281-2285 (2010).</li><li>Farhat, S., Scott, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+the+arc+process+modeling+for+fullerene+and+nanotube+production.">Review of the arc process modeling for fullerene and nanotube production.</a> Journal of Nanoscience and Nanotechnology. 6, 1189-1210 (2006).</li><li>Keidar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increasing+the+length+of+single-wall+carbon+nanotubes+in+a+magnetically+enhanced+arc+discharge.">Increasing the length of single-wall carbon nanotubes in a magnetically enhanced arc discharge.</a> Applied Physics Letters. 92, 043129-043129 (2008).</li><li>Ferrari, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Raman+spectrum+of+graphene+and+graphene+layers.">Raman spectrum of graphene and graphene layers.</a> Physical Review Letters. 97, 187401-187401 (2006).</li></ol>

Non abbiamo nulla da rivelare.

Nel istantanee video mostrato in figura 1b e 1d, per il caso che il divario interelettrodica è stato posto alla distanza di circa h = 75 mm dal fondo del magnete permanente, si deve rilevare che il cambiamento di posizione del magnete (abbiamo testato spostamento magnete lungo l&#39;asse z e ruotando il magnete sopra) comporta la deviazione del flusso del getto ad arco in direzione x che corrisponde alla direzione di J × B forza illustrato in Figura 1c. E &#39;stato a...

Tabella di reagenti e attrezzature specifiche: <table border="1"><tbody><tr><th> Nome del reagente </th><th> Azienda </th><th> Numero di catalogo </th><th> Commenti (opzionale) </th></tr><tr><td> Metanolo </td><td> Acros Organics </td><td> 423950010 </td><td></td></tr><tr><td> Nichel in polvere </td><td> Alfa Aesar </td><td> 10581 </td><td></td></tr><tr><td> Ittrio polvere </td><td> Acros Organics </td><td> 318060050 </td><td></td></tr><tr><td> Polvere di grafite </td><td> Alfa Aesar </td><td> 40799 </td><td></td></tr><tr><td> Cava di grafite asta </td><td> Saturno Industries </td><td> POCO EDM 3 </td><td></td></tr><tr><td> Magneti permanenti </td><td> McMaster-Carr </td><td> 57315K51 </td><td></td></tr><tr><td> Molibdeno foglio </td><td> Dingqi Fantascienza. e Tech. </td><td> 080504-11 </td><td></td&gt; </tr><tr><td> Ultrasonico dismembrator </td><td> Fisher Scientific </td><td> Modello 150T </td><td></td></tr><tr><td> Effetto Hall Gauss-metro </td><td> AI </td><td> Modello 100 </td><td></td></tr><tr><td> Saldatura di alimentazione </td><td> Miller elettrico </td><td> Gold Star 600SS </td><td></td></tr><tr><td> Pompa del vuoto </td><td> J / B </td><td> DV-85N </td><td></td></tr><tr><td> SEM </td><td> Zeiss </td><td> LEO 1430VP </td><td></td></tr><tr><td> TEM </td><td> JEOL </td><td> 1200 EX </td><td></td></tr><tr><td> Raman </td><td> Horiba </td><td> HR800 </td><td></td></tr></tbody></table>

simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma

Nanostrutture di carbonio, come nanotubi a parete singola carbonio (SWCNT) e grafene attrarre un diluvio di interesse degli studiosi oggi a causa della loro applicazione molto promettente per sensori molecolari, transistor ad effetto di campo e super sottile e flessibile dispositivi elettronici 1-4. Scarica ad arco anodico sostenuto dalla erosione del materiale anodo è uno dei metodi più pratici ed efficienti, in grado di fornire specifiche non-equilibrio dei processi e un afflusso elevato di materiale di carbonio per le strutture in via di sviluppo a temperatura relativamente più elevati, e di conseguenza l&#39;as- prodotti di sintesi hanno pochi difetti strutturali e una migliore cristallinità. Per migliorare ulteriormente la controllabilità e la flessibilità della sintesi di nanostrutture di carbonio a scarica ad arco, i campi magnetici possono essere applicati durante il processo di sintesi in base alle risposte forti magnetico di plasmi ad arco. E &#39;stato dimostrato che la magneticamente avanzata arco dischARGE può aumentare la durata media del SWCNT 5, stretta distribuzione del diametro delle particelle di catalizzatore metallico e nanotubi di carbonio 6, e cambiare il rapporto tra metallici e nanotubi di carbonio semiconduttori 7, così come portare a sintesi grafene 8. Inoltre, vale la pena far notare che quando si introduce una non uniforme campo magnetico con la componente normale alla corrente di arco, la forza di Lorentz lungo la direzione di J × B in grado di generare il getto di plasma e rendere efficace erogazione di particelle di ioni carbonio e flusso di calore ai campioni. Di conseguenza, su larga scala fiocchi di grafene e nanotubi di carbonio ad alta purezza a parete singola sono state generate simultaneamente da tale nuovo metodo di magneticamente avanzata arco anodica. Arco di imaging, microscopio elettronico a scansione (SEM), la trasmissione microscopio elettronico (TEM) e spettroscopia Raman sono stati impiegati per analizzare la caratterizzazione di nanostrutture di carbonio. Questi risultati indicano unaampio spettro di opportunità di manipolare con le proprietà di nanostrutture prodotte in plasmi per mezzo di controllo delle condizioni di arco.

Watch this Scientific Journal Video about Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma at JoVE.com

Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma

Scarica ad arco anodica è uno dei metodi più pratico ed efficace per sintetizzare diverse nanostrutture di carbonio. Per aumentare la controllabilità arco e la flessibilità, non uniforme campo magnetico è stato introdotto per elaborare la sintesi di uno stadio di grandi fiocchi di grafene e nanotubi di carbonio ad alta purezza a parete singola.

Sintesi simultanea di nanotubi a parete singola carbonio e del grafene in un Plasma Arc magneticamente avanzata

Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very ...

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Bioengineering

15.2K Views.  The George Washington University. Scarica ad arco anodica è uno dei metodi più pratico ed efficace per sintetizzare diverse nanostrutture di carbonio. Per aumentare la controllabilità arco e la flessibilità, non uniforme campo magnetico è stato introdotto per elaborare la sintesi di uno stadio di grandi fiocchi di grafene e nanotubi di carbonio ad alta purezza a parete singola.

Video: Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma

Graphene Coatings for Biomedical Implants

Atomically smooth graphene as a surface coating has potential to improve implant properties. This demonstrates a method for coating nitinol alloys with nanometer thick layers of graphene for applications as a stent material. Graphene was grown on copper substrates via chemical vapor deposition and then transferred onto nitinol substrates. In order to understand how the graphene coating could change biological response, cell viability of rat aortic endothelial cells and rat aortic smooth muscle cells was investigated. Moreover, the effect of graphene-coatings on cell adhesion and morphology was examined with fluorescent confocal microscopy. Cells were stained for actin and nuclei, and there were noticeable differences between pristine nitinol samples compared to graphene-coated samples. Total actin expression from rat aortic smooth muscle cells was found using western blot. Protein adsorption characteristics, an indicator for potential thrombogenicity, were determined for serum albumin and fibrinogen with gel electrophoresis. Moreover, the transfer of charge from fibrinogen to substrate was deduced using Raman spectroscopy. It was found that graphene coating on nitinol substrates met the functional requirements for a stent material and improved the biological response compared to uncoated nitinol. Thus, graphene-coated nitinol is a viable candidate for a stent material.

Graphene offers potential as a coating material for biomedical implants. In this study we demonstrate a method for coating nitinol alloys with nanometer thick layers of graphene and determine how graphene may influence implant response.

Rivestimenti grafene per impianti biomedici

Atomically smooth graphene as a surface coating has potential to improve implant properties. This demonstrates a method for coating nitinol alloys with ...

Ricerca

Bioingegneria

Localization and Relative Quantification of Carbon Nanotubes in Cells with Multispectral Imaging Flow Cytometry

Carbon-based nanomaterials, like carbon nanotubes (CNTs), belong to this type of nanoparticles which are very difficult to discriminate from carbon-rich cell structures and de facto there is still no quantitative method to assess their distribution at cell and tissue levels. What we propose here is an innovative method allowing the detection and quantification of CNTs in cells using a multispectral imaging flow cytometer (ImageStream, Amnis). This newly developed device integrates both a high-throughput of cells and high resolution imaging, providing thus images for each cell directly in flow and therefore statistically relevant image analysis. Each cell image is acquired on bright-field (BF), dark-field (DF), and fluorescent channels, giving access respectively to the level and the distribution of light absorption, light scattered and fluorescence for each cell. The analysis consists then in a pixel-by-pixel comparison of each image, of the 7,000-10,000 cells acquired for each condition of the experiment. Localization and quantification of CNTs is made possible thanks to some particular intrinsic properties of CNTs: strong light absorbance and scattering; indeed CNTs appear as strongly absorbed dark spots on BF and bright spots on DF with a precise colocalization.
This methodology could have a considerable impact on studies about interactions between nanomaterials and cells given that this protocol is applicable for a large range of nanomaterials, insofar as they are capable of absorbing (and/or scattering) strongly enough the light.

In this study, the main purpose was to monitor the cellular uptake and eventual exocytosis of carbon nanotubes (CNTs). From this perspective, we proposed here a unique method using multispectral imaging flow cytometry allowing a quantification and localization of CNTs in a statistically relevant number of cells.

Localizzazione e quantificazione relativa dei nanotubi di carbonio in cellule con immagini multispettrali Citometria a Flusso

Carbon-based nanomaterials, like carbon nanotubes (CNTs), belong to this type of nanoparticles which are very difficult to discriminate from carbon-rich ...

Synthesis of an Intein-mediated Artificial Protein Hydrogel

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

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

Sintesi di una proteina artificiale mediata da inteina Hydrogel

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

Synthesis of Keratin-based Nanofiber for Biomedical Engineering

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

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

Sintesi di nanofibre cheratina-based per Ingegneria Biomedica

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

Engineering Molecular Recognition with Bio-mimetic Polymers on Single Walled Carbon Nanotubes

Semiconducting single-wall carbon nanotubes (SWNTs) are a class of optically active nanomaterial that fluoresce in the near infrared, coinciding with the optical window where biological samples are most transparent. Here, we outline techniques to adsorb amphiphilic polymers and polynucleic acids onto the surface of SWNTs to engineer their corona phases and create novel molecular sensors for small molecules and proteins. These functionalized SWNT sensors are both biocompatible and stable. Polymers are adsorbed onto the nanotube surface either by direct sonication of SWNTs and polymer or by suspending SWNTs using a surfactant followed by dialysis with polymer. The fluorescence emission, stability, and response of these sensors to target analytes are confirmed using absorbance and near-infrared fluorescence spectroscopy. Furthermore, we demonstrate surface immobilization of the sensors onto glass slides to enable single-molecule fluorescence microscopy to characterize polymer adsorption and analyte binding kinetics.

We present a protocol for engineering the corona phase of near infrared fluorescent single walled carbon nanotubes (SWNTs) using amphiphilic polymers and DNA to develop sensors for molecular targets without known recognition elements.

Ingegneria riconoscimento molecolare con polimeri bio-mimetici sui singoli Walled nanotubi di carbonio

Semiconducting single-wall carbon nanotubes (SWNTs) are a class of optically active nanomaterial that fluoresce in the near infrared, coinciding with the ...

Targeted Plasma Membrane Delivery of a Hydrophobic Cargo Encapsulated in a Liquid Crystal Nanoparticle Carrier

The controlled delivery of drug/imaging agents to cells is critical for the development of therapeutics and for the study of cellular signaling processes. Recently, nanoparticles (NPs) have shown significant promise in the development of such delivery systems. Here, a liquid crystal NP (LCNP)-based delivery system has been employed for the controlled delivery of a water-insoluble dye, 3,3&#8242;-dioctadecyloxacarbocyanine perchlorate (DiO), from within the NP core to the hydrophobic region of a plasma membrane bilayer. During the synthesis of the NPs, the dye was efficiently incorporated into the hydrophobic LCNP core, as confirmed by multiple spectroscopic analyses. Conjugation of a PEGylated cholesterol derivative to the NP surface (DiO-LCNP-PEG-Chol) enabled the binding of the dye-loaded NPs to the plasma membrane in HEK 293T/17 cells. Time-resolved laser scanning confocal microscopy and F&#246;rster resonance energy transfer (FRET) imaging confirmed the passive efflux of DiO from the LCNP core and its insertion into the plasma membrane bilayer. Finally, the delivery of DiO as a LCNP-PEG-Chol attenuated the cytotoxicity of DiO; the NP form of DiO exhibited ~30-40% less toxicity compared to DiOfree delivered from bulk solution. This approach demonstrates the utility of the LCNP platform as an efficient modality for the membrane-specific delivery and modulation of hydrophobic molecular cargos.

A liquid crystal nanoparticle (LCNP) nanocarrier is exploited as a vehicle for the controlled delivery of a hydrophobic cargo to the plasma membrane of living cells.

Targeted membrana plasmatica di consegna di un idrofobo Cargo incapsulato in un cristallo nanoparticelle Carrier Liquid

The controlled delivery of drug/imaging agents to cells is critical for the development of therapeutics and for the study of cellular signaling processes. ...

DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of flexible polymers nor of rigid rods. Underlying filaments remain outstretched due to their non-vanishing backbone stiffness, which is quantified via the persistence length (lp), but they are also subject to strong thermal fluctuations. Their finite bending stiffness leads to unique, non-trivial collective mechanics of bulk networks, enabling the formation of stable scaffolds at low volume fractions while providing large mesh sizes. This underlying principle is prevalent in nature (e.g., in cells or tissues), minimizing the high molecular content and thereby facilitating diffusive or active transport. Due to their biological implications and potential technological applications in biocompatible hydrogels, semiflexible polymers have been subject to considerable study. However, comprehensible investigations remained challenging since they relied on natural polymers, such as actin filaments, which are not freely tunable. Despite these limitations and due to the lack of synthetic, mechanically tunable, and semiflexible polymers, actin filaments were established as the common model system. A major limitation is that the central quantity lp cannot be freely tuned to study its impact on macroscopic bulk structures. This limitation was resolved by employing structurally programmable DNA nanotubes, enabling controlled alteration of the filament stiffness. They are formed through tile-based designs, where a discrete set of partially complementary strands hybridize in a ring structure with a discrete circumference. These rings feature sticky ends, enabling the effective polymerization into filaments several microns in length, and display similar polymerization kinetics as natural biopolymers. Due to their programmable mechanics, these tubes are versatile, novel tools to study the impact of lp on the single-molecule as well as the bulk scale. In contrast to actin filaments, they remain stable over weeks, without notable degeneration, and their handling is comparably straightforward.

Semiflexible polymers display unique mechanical properties that are extensively applied by living systems. However, systematic studies on biopolymers are limited since properties such as polymer rigidity are inaccessible. This manuscript describes how this limitation is circumvented by programmable DNA nanotubes, enabling experimental studies on the impact of filament rigidity.

Nanotubi di DNA come un Versatile strumento per lo studio di polimeri semiflessibili

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

Melt Electrospinning Writing of Three-dimensional Poly(&amp;#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

Sciogliere elettrofilatura scrittura di scaffold tridimensionale Poly(ε-caprolactone) con morfologie controllabile per applicazioni di ingegneria del tessuto

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Microhoneycomb Monoliths Prepared by the Unidirectional Freeze-drying of Cellulose Nanofiber Based Sols: Method and Extensions

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb monoliths (MHMs) with micrometer-scale channels are expected as efficient platforms for reactions and separations because of their large surface areas. Up to now, MHMs have been prepared by a unidirectional freeze-drying (UDF) method only from very limited precursors. Herein, we report a protocol from which a series of MHMs consisting of different components can be obtained. Recently, we found that cellulose nanofibers function as a distinct structure-directing agent towards the formation of MHMs through the UDF process. By mixing the cellulose nanofibers with water soluble substances which do not yield MHMs, a variety of composite MHMs can be prepared. This significantly enriches the chemical constitution of MHMs towards versatile applications.

Here, we present a general protocol to prepare a variety of microhoneycomb monoliths (MHMs) in which fluid can pass through with an extremely low pressure drop. MHMs obtained are expected to be used as filters, catalyst supports, flow-type electrodes, sensors and scaffolds for biomaterials.

Monoliti Microhoneycomb preparati dalla liofilizzazione unidirezionale di cellulosa nanofibra basato Sols: metodo ed estensioni

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb ...

Synthesis of Multi-walled Carbon Nanotubes Modified with Silver Nanoparticles and Evaluation of Their Antibacterial Activities and Cytotoxic Properties

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver MWCNTs were prepared by the reductive deposition of silver from an aqueous solution of AgNO3 on the oxidized MWCNTs. Given the unique color of the CNTs, it was not possible to apply them to the minimum inhibitory concentration or mitochondrial toxicity assays to evaluate the toxicity and antibacterial properties, since they would interfere with the assays. The inhibition zone and minimum bactericidal concentration for the Ag-MWCNTs were measured and Live/Dead and Trypan Blue assays were used to measure the toxicity and antibacterial properties without interfering with the color of the CNTs.

In this study, antimicrobial nanomaterials were synthesized by acidic oxidation of multiwalled carbon nanotubes and subsequent reductive deposition of silver nanoparticles. Antimicrobial activity and cytotoxicity tests were performed with the as-prepared nanomaterials.

Sintesi di nanotubi di carbonio Multi-parete modificati con nanoparticelle di argento e valutazione dell'attività antibatterica e proprietà citotossiche

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver ...