L'autore ringrazia il Prof Y. Ozaki (Kwansei Gakuin University) e Dr. T. Itoh (National Institute of Advanced Industrial Science and Technology) per la loro proficua discussione su quest'opera. Questo lavoro è stato supportato da KAKENHI (sovvenzione per Scientific Research C) dal Ministero della pubblica istruzione, cultura, sport, scienza e tecnologia (n. 16K 05671).

1. preparazione del campione
<ol><li>
Preparazione di nanoparticelle di argento colloidale 20<ol>
<li>Per fabbricare le nanoparticelle d'argento colloidale, sciogliere 0,030 g di nitrato d'argento e 0,030 g di citrato trisodico biidrato in 150 mL di acqua in un pallone a fondo tondo 200 mL.</li>
		<li>Combinare la beuta con un refrigerante a ricadere (Dimroth).</li>
		<li>Agitare la soluzione in un matraccio con una barra magnetica di agitatore e mescolare. Quindi, riscaldare la soluzione mescolando nel matraccio in bagno d'olio a 150 ° C per 60 min. Nota: La soluzione diventerà grigio giallo, poi latteo.</li>
		<li>Raffreddare la sospensione a temperatura ambiente e a mantenere la sospensione nel pallone coperto con foglio di alluminio in frigorifero. Nota: Il protocollo può essere sospesa a questo punto. Utilizzare le nanoparticelle colloidali, dopo la conservazione in frigorifero, entro un mese.</li>
	</ol>
</li>
	<li>
Preparazione del campione per multi-colorato lampeggiante emissione 11<ol>
<li>Per preparare un vetrino da microscopio, lavare a mano, una lastra di vetro con sapone e risciacquare con acqua.</li>
		<li>Aggiungere 0,1% soluzione acquosa di poli-L-lisina per la lastra di vetro e rimuovere la soluzione con un ventilatore.</li>
		<li>Aggiungere la sospensione colloidale d'argento per la lastra di vetro e rimuovere la sospensione con un ventilatore.</li>
		<li>Racchiudere un'area di rilascio sulla lastra di vetro con una penna di liquido bloccante.</li>
		<li>Acqua distillata goccia sulla lastra di vetro e coprire con un'altra lastra di vetro per creare un vetrino da microscopio e impedire l'evaporazione di acqua.</li>
	</ol>
</li>
	<li>
Preparazione del campione per monotono SERS lampeggiante colorato 7 , 8 , 9 , 10<ol>
<li>Per preparare un vetrino da microscopio, lavare a mano, una lastra di vetro con sapone e risciacquare con acqua.</li>
		<li>Mescolare la sospensione colloidale d'argento con la tintura di thiacyanine o thiacarbocyanine (25 o 4 µM, rispettivamente) e una soluzione acquosa di NaCl (10 mM) a un rapporto volumetrico di 2:1:1.</li>
		<li>Eliminare la sospensione del campione sulla piastra di vetro e rimuovere la sospensione con un ventilatore.</li>
		<li>Racchiudere un'area di rilascio sulla lastra di vetro con una penna di liquido bloccante.</li>
		<li>Goccia di una soluzione acquosa di NaCl (1 M) sul piatto di vetro per immobilizzare le nanoparticelle d'argento e coprire con un'altra lastra di vetro per creare una piastra di scorrimento microscopio e impedire che la soluzione di evaporazione.</li>
	</ol>
</li>
</ol>2. osservazione del lampeggiante nanoparticelle d'argento
<ol><li>
Illuminazione del campione
	<ol>
<li>Posizionare la piastra di vetro di campione preparata con protocollo 1.2 o 1.3 sulla scena di un microscopio invertito.</li>
		<li>Illuminare la lastra di vetro del campione usando la luce bianca attraversa un condensatore per campo oscuro e la messa a fuoco su vari punti colorati (blu, verde, gialli e rossi) sulla lastra di vetro utilizzando una lente obiettiva (60 X).</li>
		<li>Illuminare la lastra di vetro di campione utilizzando un fascio di luce attenuata, consegnato ad un angolo di 30° rispetto alla superficie del campione, da un laser a diodi a stato solido pompato (DPSS) continuo-fluttui (cw) attraverso un filtro antidisturbo.</li>
		<li>Per utilizzare laser illuminazione per osservare l'argento nanoaggregati come macchie di colore monotoni in zona dello stesso colore, spostare l'area di illuminazione laser al centro della vista e concentrarsi sui punti sulla lastra di vetro regolando la fase nella direzione z.</li>
	</ol>
</li>
	<li>
Osservazione del lampeggiante
	<ol>
<li>Inserire un filtro passa-lungo dopo la lente dell'obiettivo e illuminare la lastra di vetro di campione utilizzando un fascio di cw-laser DPSS consegnato ad un angolo di 30° rispetto la superficie del campione attraverso un filtro antidisturbo.</li>
		<li>Trovare il lampeggio macchie come mostrato in Figura 1 (Vedi anche Figura S1 nel materiale supplementare) spostando il palco nelle direzioni x e y.</li>
		<li>Registrare video dei luoghi lampeggianti con il microscopio invertito, accoppiato ad una fotocamera raffreddato digitale charge coupled device (CCD), che ha una risoluzione temporale di 61-120 ms, per 20 min.</li>
	</ol>
</li>
</ol>3. analisi del lampeggiante SERS
<ol><li>
Derivazione del profilo di tempo dal video
	<ol>
<li>Nel software che controlla la telecamera CCD, aprire il file video.</li>
		<li>Per selezionare i punti lampeggianti e zona scura, trascinare aree che coprono separatamente aree con e senza macchie nell'immagine video.</li>
		<li>Per derivare i profili orario di intensità di segnale dal lampeggiante macchie e aree scure nel video, selezionare Analisi temporale nell'analisie fare clic su Calcola nella finestra Analisi temporale .</li>
		<li>Salvare i dati come file di testo.</li>
	</ol>
</li>
	<li>
Analisi del profilo tempo
	<ol>
<li>Appiattire una previsione del profilo orario sottraendo il profilo orario dall'area scura e/o raccordo con una funzione polinomiale, come mostrato nelle figure 2A e 2B.</li>
		<li>Valutare un'intensità media della linea di base che consiste di circa 2000 punti, iobasee una deviazione standard di intensità della linea di base, σ, come mostrato nelle figure 2 e 2D.</li>
		<li>Distinguere eventi luminosi da eventi oscuri con maggiore intensità di una soglia di hobase + 3 σ e registrare la durata di ogni evento. Nella Figura 3, ad esempio, registrare l'evento da 0 a 3.5476 s come l'evento scuro (con una durata di t = 3.5476 s) e registrare l'evento da 3.5476 a 4.0981 s come l'evento luminoso (con una durata di t = 0.5505 s). Ripetere la procedura come indicato nella tabella 1.</li>
		<li>Contare il numero di eventi di chiari e scuri per ogni durata, come espresso nelle linee prime e seconda della tabella 2.</li>
		<li>Sommare il numero di eventi per ogni durata, fatta eccezione per eventi più brevi di durata t. Come espresso nella seconda e terza riga della tabella 2, ad esempio, sommare il numero di eventi per ogni durata (fatta eccezione per gli eventi per t = 0.0612 s) come 41 + 18 + 9 +...; il risultato è uguale la somma per t = 0.1223 s, cioè 103.</li>
		<li>Dividere le sommatorie per ogni durata e normalizzarli. Come espresso nella tabella 2, per esempio, dividere la somma per durata t = 0.0612 s dalla durata 0.0612 s. Il risultato è 3,351.5791. Poi, dividere il risultato per il totale dei risultati nella quarta riga nella tabella 2. La distribuzione di probabilità è derivata per essere 0.64494.</li>
		<li>Tracciare le distribuzioni di probabilità per il brillante eventi Psu(t) contro la loro durata t in un grafico del logaritmo logaritmo e montare Log10Psu(t) di Log10 (<img alt="Equation 1" src="/files/ftp_upload/56729/56729eq1.jpg">) per dedurre il power legge esponente αsu per uno specifico lampeggio spot. Se Psu(t) viene montata dal <img alt="Equation 1" src="/files/ftp_upload/56729/56729eq1.jpg"> </img>, la linea componibile devia dai terreni a piccoli valori di Psu(t), come indicato dalla linea tratteggiata in Figura 4A.</li>
		<li>Tracciare le distribuzioni di probabilità per eventi oscuri Poff(t) contro la loro durata t in un grafico del logaritmo logaritmo e Log10Poff(t) in forma di Log10( <img alt="Equation 3" src="/files/ftp_upload/56729/56729eq3.jpg"> dedurre power legge esponente αfuori e il troncamento tempo τ dal lampeggio stesso spot. Se Poff(t) viene montata dal <img alt="Equation 3" src="/files/ftp_upload/56729/56729eq3.jpg"> </img>, la curva si discosta dai terreni a piccoli valori di Poff(t).</li>
		<li>Ripetere 3.2.1 a 3.2.8 per gli altri punti lampeggianti nel video.</li>
	</ol>
</li>
</ol>

<ol>
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Rev. 37, 1052-1060 (2008).</li><li>Kitahama, Y., Ozaki, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+blinking+SERS+by+a+power+law+with+an+exponential+function.">Analysis of blinking SERS by a power law with an exponential function.</a> Frontiers of Surface-Enhanced Raman Scattering: Single-Nanoparticles and Single Cells. , (2014).</li><li>Kitahama, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Truncated+Power+Law+Analysis+of+Blinking+SERS.">Truncated Power Law Analysis of Blinking SERS.</a> Frontiers of Plasmon Enhanced Spectroscopy Volume 1 (ACS Symposium series Vol. 1245). , (2016).</li><li>Bizzarri, A. 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S., Itoh, T., Ozaki, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Different+behaviour+of+molecules+in+dark+SERS+state+on+colloidal+Ag+nanoparticles+estimated+by+truncated+power+law+analysis+of+blinking+SERS.">Different behaviour of molecules in dark SERS state on colloidal Ag nanoparticles estimated by truncated power law analysis of blinking SERS.</a> Phys. Chem. Chem. Phys. 17, 21204-21210 (2015).</li><li>Kitahama, Y., Nagahiro, T., Tanaka, Y., Itoh, T., Ozaki, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+blinking+from+multicoloured+SERS-active+Ag+colloidal+nanoaggregates+with+poly-L-lysine+via+truncated+power+law.">Analysis of blinking from multicoloured SERS-active Ag colloidal nanoaggregates with poly-L-lysine via truncated power law.</a> J. Raman. 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L'autore non ha nulla di divulgare.

Dallo svincolo di nanoaggregati argento, SERS è emessa. Quindi, abbiamo bisogno di preparare nanoaggregati piuttosto che nanoparticelle colloidali, che sono coperti con gli anioni citrato. Aggregati d'argento sono formati dall'effetto creato tramite l'aggiunta di poli-L-lisina, che ha -NH3+ ed è l'origine della SERS, la salatura o cationi Na+ da NaCl, come mostrato in Figura S2 del materiale supplementare. Inoltre, per illuminare i molti punti nella vasta area, il raggi...

Superficie-enhanced Raman scattering (SERS) è altamente sensibile spettroscopia Raman da una superficie di metallo nobile. Poiché lo spettro Raman fornisce informazioni dettagliate sulla struttura molecolare sulla base delle posizioni di picco acuto, attraverso i modi vibrazionali di gruppi funzionali nelle molecole, è possibile analizzare le informazioni di una singola molecola su una superficie metallica usando SERS1,2,3. Da un argento nanoaggregati con un adsorbato a livello di singola molecola, un segnale lampeggio è osservato1,2,3,4,5,6, 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16e lo spettro fluttua1,2,3,4,5,6,7,8, 9,10,11,12,13,14. Lampeggiante può essere indotta da una singola molecola che casualmente si muove dentro e fuori un maggiore campo elettromagnetico (EM) in un incrocio di nanoaggregati d'argento di dimensioni nanometriche. Di conseguenza, lampeggiante è considerato prova semplice per il rilevamento di singola molecola, confrontato con una tecnica che utilizza una distribuzione di Poisson di intensità di SERS e un bi-analita2,3,17. Tuttavia, i meccanismi dettagliati dello spettro lampeggio e fluttuante, che può dipendere fortemente il comportamento molecolare sulla superficie Ag, sono ancora controversi.
Negli studi precedenti, lampeggiante SERS è stato analizzato utilizzando la funzione di autocorrelazione, che può calcolare il coefficiente di diffusione e la concentrazione delle molecole in movimento dentro e fuori un'avanzata EM campo12,13,14 . Inoltre, un punteggio di deviazione standard normalizzata, che rappresenta instabilità dell'intensità totale, è stato derivato dal profilo tempo del segnale15. Tuttavia, questi approcci analitici possono basarsi sul comportamento di alcune molecole. Al contrario, in un imaging di Super-risoluzione del lampeggiante SERS, comportamento di singola molecola in un maggiore campo di EM può essere identificato16. Tuttavia, queste tecniche possono ottenere tali parametri solo in un maggiore campo di EM. Il comportamento casuale di una singola molecola all'interno di una vasta gamma (per esempio, nel lampeggiante SERS) può essere rappresentato come una legge di potenza piuttosto che una media4,5,6,7,8 ,9,10,11, simili a fluorescenza lampeggia da un singolo semiconductor quantum dot (QD)18,19. Utilizzando un potere legge analisi4,5,6,7,8,9,10,11, comportamento molecolare può essere stimato in stato brillante (nel campo EM avanzato) sia stato scuro10; ovvero, il comportamento della molecola su tutta la superficie d'argento può essere stimato.
Per questa tecnica, argento colloidale nanoaggregati sono usato4,5,6,7,8,9,10,11. Questi nanoaggregati mostrano varie bande di risonanza (LSPR) plasmonica di superficie localizzata che influiscono fortemente rafforzate campi elettromagnetici quando sono eccitati a determinate lunghezze d'onda. Così, argento SERS-attivo nanoparticelle presenti in sospensione colloidale e alcuni dati immediatamente possa essere ottenuto. Nel caso di semplice nanostrutture, che hanno accordi, forme e dimensioni specifiche, la dipendenza di LSPR della SERS lampeggiante può celare altre dependences7; vale a dire, se la nanostruttura buona o cattiva a LSPR viene utilizzata, i parametri sarà costanti, e le altre dipendenze pertanto saranno nascosto. Analisi della legge di potenza sono stato utilizzato per scoprire varie dipendenze della SERS lampeggiante da argento colloidale nanoaggregati4,5,6,7,8, 9 , 10 , 11.

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	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Silver nitrate, 99.8%</td>
			<td style="width:83px;">Wako</td>
			<td style="width:119px;">194-00832</td>
			<td style="width:211px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:227px;">Trisodium citrate dihydrate, 99. %</td>
			<td style="width:83px;">Wako</td>
			<td style="width:119px;">191-01785</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:227px;">Poly-L-lysine aqueous solution, 0.1%</td>
			<td style="width:83px;">Sigma-Aldrich</td>
			<td style="width:119px;">P8920</td>
			<td></td>
		</tr>
		<tr height="116">
			<td height="116" style="height:116px;width:227px;">3,3&#39;-disulfopropylthiacyanine triethylamine</td>
			<td style="width:83px;">Hayashibara Biochemical Laboratories</td>
			<td style="width:119px;">NK-2703</td>
			<td>a kind of thiacyanine dyes</td>
		</tr>
		<tr height="116">
			<td height="116" style="height:116px;width:227px;">3,3&#39;-diethyl-5,5&#39;-dichloro-9-methylthiacarbocyanine iodine salt</td>
			<td style="width:83px;">Hayashibara Biochemical Laboratories</td>
			<td style="width:119px;">SMP-9</td>
			<td>a kind of thiacarobocyanine dyes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Sodium chloride, 99.5%</td>
			<td style="width:83px;">Wako</td>
			<td style="width:119px;">191-01665</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Dimroth condenser</td>
			<td style="width:83px;">Iwaki</td>
			<td style="width:119px;">61-9722-22</td>
			<td>perchased from AS ONE</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Magnetic stirrer</td>
			<td style="width:83px;">Corning</td>
			<td style="width:119px;">DC-420D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Oil bath</td>
			<td style="width:83px;">Advantech</td>
			<td style="width:119px;">OS-220</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Glass plate</td>
			<td style="width:83px;">Matsunami</td>
			<td style="width:119px;">S-1112</td>
			<td>Microscope slide</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Blower</td>
			<td style="width:83px;">Hozan</td>
			<td style="width:119px;">Z-288</td>
			<td>Air duster</td>
		</tr>
		<tr height="116">
			<td height="116" style="height:116px;width:227px;">Liquid blocker pen</td>
			<td style="width:83px;">Daido Sangyo</td>
			<td style="width:119px;"></td>
			<td style="width:211px;">LIQUID BLOCKER (Super Pap Pen). Ready-to-use hydrophobic barrier pen designed for immunohistochemistry applications</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Inverted microscope</td>
			<td style="width:83px;">Olympus</td>
			<td style="width:119px;">IX-70</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Objective lens</td>
			<td style="width:83px;">Olympus</td>
			<td style="width:119px;">LCPlanFl 60&#215;</td>
			<td>NA 0.7</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Dark field condenser</td>
			<td style="width:83px;">Olympus</td>
			<td style="width:119px;">U-DCD</td>
			<td style="width:211px;">NA 0.8&#8211;0.92</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:227px;">Cooled digital CCD camera</td>
			<td style="width:83px;">Hamamatsu</td>
			<td style="width:119px;">ORCA-AG</td>
			<td style="width:211px;">controlled by software Aqua Cosmos</td>
		</tr>
		<tr height="59">
			<td height="59" style="height:59px;width:227px;">Software for the cooled digital CCD camera</td>
			<td style="width:83px;">Hamamatsu</td>
			<td style="width:119px;">AquaCosmos</td>
			<td style="width:211px;">used for also derivation of the time-profiles from the blinking spots in the video&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Color CCD camera</td>
			<td style="width:83px;">ELMO</td>
			<td style="width:119px;">TNC-C920</td>
			<td>not used for analysis</td>
		</tr>
		<tr height="59">
			<td height="59" style="height:59px;width:227px;">DPSS laser</td>
			<td style="width:83px;">RGB laser system</td>
			<td style="width:119px;">NovaPro532-75</td>
			<td style="width:211px;">&#955; = 532 nm; 
			60 mW (corresponds to a power density of 600 W/cm2)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Interference filter</td>
			<td style="width:83px;">Semrock</td>
			<td style="width:119px;">LL01-532-12.5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">Long pass filter</td>
			<td style="width:83px;">Semrock</td>
			<td style="width:119px;">BLP01-532R-25</td>
			<td></td>
		</tr>
		<tr height="59">
			<td height="59" style="height:59px;width:227px;">Software for the distinguishment and counting of the bright/dark events</td>
			<td style="width:83px;">home-maid</td>
			<td style="width:119px;"></td>
			<td>programmed by C++</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:227px;">Software for the fitting by a power law</td>
			<td style="width:83px;">LightStone</td>
			<td style="width:119px;">Origin6.1</td>
			<td></td>
		</tr>
	</tbody>
</table>

observation and analysis of blinking surface-enhanced raman scattering

Da una singola molecola in un incrocio di nanoaggregati argento, lampeggiante superficie-enhanced Raman scattering (SERS) è osservato. Qui, un protocollo è presentato su come preparare il SERS-attivo argento nanoaggregati, registrare un video di alcuni punti lampeggianti dell'immagine microscopica e analizzare le statistiche di lampeggiante. In questa analisi, una legge di potenza riproduce le distribuzioni di probabilità per eventi luminosi rispetto alla loro durata. Le distribuzioni di probabilità per eventi oscuri sono dotate di una legge di potenza con una funzione esponenziale. I parametri della legge di potere rappresentano il comportamento molecolare negli Stati sia chiaro e scuri. Il modello di random walk e la velocità della molecola su tutta la superficie d'argento può essere stimati. È difficile stimare anche quando si utilizzano medie, funzioni di autocorrelazione e super-risoluzione SERS imaging. In futuro, analisi di legge di potenza dovrebbero combinarsi con imaging spettrale, perché le origini del lampeggiante non possono essere confermate da questo metodo di analisi da solo.

Dall'argento nanoaggregati con poli-L-lisina preparato dal protocollo 1.2, si osservano macchie multicolore lampeggiante da SERS e superficie-enhanced fluorescenza, come illustrato nella Figura 111. Al contrario, monotoni punti colorati lampeggiante da SERS sono stati osservati per i nanoaggregati d'argento con le molecole di colorante preparate dal protocollo 1.37,8,</sup...

Watch this Scientific Journal Video about Observation and Analysis of Blinking Surface-enhanced Raman Scattering at JoVE.com

Observation and Analysis of Blinking Surface-enhanced Raman Scattering

Questo protocollo descrive l'analisi del lampeggiante superficie-enhanced Raman scattering dovuto il cammino casuale di una singola molecola su una superficie d'argento utilizzando leggi di potenza.

Osservazione e analisi del lampeggiante superficie-enhanced Raman Scattering

From a single molecule at a silver nanoaggregate junction, blinking surface-enhanced Raman scattering (SERS) is observed. Here, a protocol is presented on ...

observation-and-analysis-of-blinking-surface-enhanced-raman-scattering

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7.3K Views.  Kwansei Gakuin University. Questo protocollo descrive l'analisi del lampeggiante superficie-enhanced Raman scattering dovuto il cammino casuale di una singola molecola su una superficie d'argento utilizzando leggi di potenza.

Video: Observation and Analysis of Blinking Surface-enhanced Raman Scattering

A Filter-based Surface Enhanced Raman Spectroscopic Assay for Rapid Detection of Chemical Contaminants

We demonstrate a method to fabricate highly sensitive surface-enhanced Raman spectroscopic (SERS) substrates using a filter syringe system that can be applied to the detection of various chemical contaminants. Silver nanoparticles (Ag NPs) are synthesized via reduction of silver nitrate by sodium citrate. Then the NPs are aggregated by sodium chloride to form nanoclusters that could be trapped in the pores of the filter membrane. A syringe is connected to the filter holder, with a filter membrane inside. By loading the nanoclusters into the syringe and passing through the membrane, the liquid goes through the membrane but not the nanoclusters, forming a SERS-active membrane. When testing the analyte, the liquid sample is loaded into the syringe and flowed through the Ag NPs coated membrane. The analyte binds and concentrates on the Ag NPs coated membrane. Then the membrane is detached from the filter holder, air dried and measured by a Raman instrument. Here we present the study of the volume effect of Ag NPs and sample on the detection sensitivity as well as the detection of 10 ppb ferbam and 1 ppm ampicillin using the developed assay.

A procedure for fabrication and performing the filter-based surface enhanced Raman spectroscopic (SERS) assay for the detection of chemical contaminants (i.e., pesticide ferbam and antibiotic ampicillin) is presented.

Una Superficie-filtro basato avanzata Raman spettroscopica Assay per Rapid individuazione dei contaminanti chimici

We demonstrate a method to fabricate highly sensitive surface-enhanced Raman spectroscopic (SERS) substrates using a filter syringe system that can be ...

Ricerca

Chimica

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

Preparazione del biopolimero Aerogels che utilizzano solventi verdi

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a technique used to measure the size distribution of polymer solutions or colloidal particles. Although this technique is widely used for the assessment of polymer solutions, it is difficult to measure the particle size in concentrated solutions due to the multiple scattering effect or strong light absorption. Therefore, the concentrated solutions should be diluted before measurement. Implementation of the confocal optical component in a dynamic light scattering microscope1 helps to overcome this barrier. Using such a microscopic system, both transparent and turbid systems can be analyzed under the same experimental setup without a dilution. As a representative example, a size distribution measurement of a temperature-responsive polymer solution was performed. The sizes of the polymer chains in an aqueous solution were several tens of nanometers at a temperature below the lower critical solution temperature (LCST). In contrast, the sizes increased to more than 1.0 &#181;m when above the LCST. This result is consistent with the observation that the solution turned turbid above the LCST.

A protocol for the direct measurement of particle size distribution in concentrated solutions using dynamic light scattering microscopy is presented.

Misura della dimensione delle particelle di distribuzione in torbidi soluzioni da Dynamic Light Scattering Microscopia

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a ...

A Novel Technique for Raman Analysis of Highly Radioactive Samples Using Any Standard Micro-Raman Spectrometer

A novel approach for the Raman measurement of nuclear materials is reported in this paper. It consists of the enclosure of the radioactive sample in a tight capsule that isolates the material from the atmosphere. The capsule can optionally be filled with a chosen gas pressurized up to 20 bars. The micro-Raman measurement is performed through an optical-grade quartz window. This technique permits accurate Raman measurements with no need for the spectrometer to be enclosed in an alpha-tight containment. It therefore allows the use of all options of the Raman spectrometer, like multi-wavelength laser excitation, different polarizations, and single or triple spectrometer modes. Some examples of measurements are shown and discussed. First, some spectral features of a highly radioactive americium oxide sample (AmO2) are presented. Then, we report the Raman spectra of neptunium oxide (NpO2) samples, the interpretation of which is greatly improved by employing three different excitation wavelengths, 17O doping, and a triple mode configuration to measure the anti-stokes Raman lines. This last feature also allows the estimation of the sample surface temperature. Finally, data that were measured on a sample from Chernobyl lava, where phases are identified by Raman mapping, are shown.

We present a technique for Raman spectroscopic analysis of highly radioactive samples compatible with any standard micro-Raman spectrometer, without any radioactive contamination of the instrument. We also show some applications using actinide compounds and irradiated fuel materials.

Una tecnica innovativa per l&#39;analisi Raman di campioni altamente radioattivo Uso di qualsiasi standard Micro-Raman Spectrometer

A novel approach for the Raman measurement of nuclear materials is reported in this paper. It consists of the enclosure of the radioactive sample in a ...

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 e IR Spettroelettrochimica metodi come strumenti per analizzare composti organici coniugati

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

DNA-magnetic Particle Binding Analysis by Dynamic and Electrophoretic Light Scattering

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the evaluation of DNA-magnetic particles binding via dynamic light scattering (DLS) and electrophoretic light scattering (ELS). Analysis by DLS provides valuable information on the physicochemical properties of particles including particle size, polydispersity, and zeta potential. The latter describes the surface charge of the particle which plays major role in electrostatic binding of materials such as DNA. Here, a comparative analysis exploits three chemical modifications of nanoparticles and microparticles and their effects on DNA binding and elution. Chemical modifications by branched polyethylenimine, tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane are investigated. Since DNA exhibits a negative charge, it is expected that zeta potential of particle surface will decrease upon binding of DNA. Forming of clusters should also affect particle size. In order to investigate the efficiency of these particles in isolation and elution of DNA, the particles are mixed with DNA in low pH (~6), high ionic strength and dehydration environment. Particles are washed on magnet and then DNA is eluted by Tris-HCl buffer (pH = 8). DNA copy number is estimated using quantitative polymerase chain reaction (PCR). Zeta potential, particle size, polydispersity and quantitative PCR data are evaluated and compared. DLS is an insightful and supporting method of analysis that adds a new perspective to the process of screening of particles for DNA isolation.

This protocol describes the synthesis of magnetic particles and evaluation of their DNA-binding properties via dynamic and electrophoretic light scattering. This method focuses on monitoring changes in particle size, their polydispersity and zeta potential of particle surface which play major role in binding of materials such as DNA.

DNA-magnetoscopico associazione analisi di dispersione della luce dinamica ed elettroforetica

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the ...

Resolving Water, Proteins, and Lipids from In Vivo Confocal Raman Spectra of Stratum Corneum through a Chemometric Approach

Development of this in vivo confocal Raman spectroscopic method enables the direct measurement of water, proteins, and lipids with depth resolution in human subjects. This information is very important for skin-related diseases and characterizing skin care product performance. This protocol illustrates a method for confocal Raman spectra collection and the subsequent analysis of the spectral dataset leveraging chemometrics. The goal of this method is to establish a standard protocol for data collection and provide general guidance for data analysis. Preprocessing (e.g., removal of outlier spectra) is a critical step when processing large datasets from clinical studies. As an example, we provide guidance based on prior knowledge of a dataset to identify the types of outliers and develop specific strategies to remove them. A principal component analysis is performed, and the loading spectra are compared with spectra from reference materials to select the number of components used in the final multivariate curve resolution (MCR) analysis. This approach is successful for extracting meaningful information from a large spectral dataset.

Here, we present a protocol for collection of confocal Raman spectra from human subjects in clinical studies combined with chemometric approaches for spectral outlier removal and the subsequent extraction of key features.

Risolvere acqua, proteine e lipidi da In Vivo Confocal Raman Spectra di Stratum Corneum attraverso un approccio chemiometrico

Development of this in vivo confocal Raman spectroscopic method enables the direct measurement of water, proteins, and lipids with depth resolution in ...

Application of Voltage in Dynamic Light Scattering Particle Size Analysis

Dynamic light scattering (DLS) is a common method for characterizing the size distribution of polymers, proteins, and other nano- and microparticles. Modern instrumentation permits measurement of particle size as a function of time and/or temperature, but currently there is no simple method for performing DLS particle size distribution measurements in the presence of applied voltage. The ability to perform such measurements would be useful in the development of electroactive, stimuli-responsive polymers for applications such as sensing, soft robotics, and energy storage. Here, a technique using applied voltage coupled with DLS and a temperature ramp to observe changes in aggregation and particle size in thermoresponsive polymers with and without electroactive monomers is presented. The changes in aggregation behavior observed in these experiments were only possible through the combined application of voltage and temperature control. To obtain these results, a potentiostat was connected to a modified cuvette in order to apply voltage to a solution. Changes in polymer particle size were monitored using DLS in the presence of constant voltage. Simultaneously, current data were produced, which could be compared with particle size data, to understand the relationship between current and particle behavior. The polymer poly(N-isopropylacrylamide) (pNIPAM) served as a test polymer for this technique, as pNIPAM's response to temperature is well-studied. Changes in the lower-critical solution temperature (LCST) aggregation behavior of pNIPAM and poly(N-isopropylacrylamide)-block-poly(ferrocenylmethyl methacrylate), an electrochemically active block-copolymer, in the presence of applied voltage are observed. Understanding the mechanisms behind such changes will be important when trying to achieve reversible polymer structures in the presence of applied voltage.

Here, a protocol to apply voltage to solution during dynamic light scattering particle size measurements with the intent to explore the effect of voltage and temperature changes on polymer aggregation is presented.

Applicazione di tensione nell'analisi dinamica delle particelle di dispersione della luce

Dynamic light scattering (DLS) is a common method for characterizing the size distribution of polymers, proteins, and other nano- and microparticles. ...

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional &#960;-conjugate Systems

Femtosecond time-resolved stimulated Raman spectroscopy is a promising method of observing the structural dynamics of short-lived transients with near infrared (near-IR) transitions, because it can overcome the low sensitivity of spontaneous Raman spectrometers in the near-IR region. Here, we describe technical details of a femtosecond time-resolved near-IR multiplex stimulated Raman spectrometer that we have recently developed. A description of signal generation and optimization, measurement, data acquisition, and calibration and correction of recorded data is provided as well. We present an application of our spectrometer to analyze the excited-state dynamics of &#946;-carotene in toluene solution. A C=C stretch band of &#946;-carotene in the second lowest excited singlet (S2) state and the lowest excited singlet (S1) state is clearly observed in the recorded time-resolved stimulated Raman spectra. The femtosecond time-resolved near-IR stimulated Raman spectrometer is applicable to the structural dynamics of &#960;-conjugate systems from simple molecules to complex materials.

Details of signal generation and optimization, measurement, data acquisition, and data handling for a femtosecond time-resolved near-IR stimulated Raman spectrometer are described. A near infrared stimulated Raman study on the excited-state dynamics of &#946;-carotene in toluene is shown as a representative application.

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional .

Femtosecond time-resolved stimulated Raman spectroscopy is a promising method of observing the structural dynamics of short-lived transients with near ...

Preparation of Nanoparticles for ToF-SIMS and XPS Analysis

Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, chemistry, and their potential to enable advanced materials. To effectively understand and regulate the physico-chemical properties and potential adverse effects of nanoparticles, validated measurement procedures for the various properties of nanoparticles need to be developed. While procedures for measuring nanoparticle size and size distribution are already established, standardized methods for analysis of their surface chemistry are not yet in place, although the influence of the surface chemistry on nanoparticle properties is undisputed. In particular, storage and preparation of nanoparticles for surface analysis strongly influences the analytical results from various methods, and in order to obtain consistent results, sample preparation must be both optimized and standardized. In this contribution, we present, in detail, some standard procedures for preparing nanoparticles for surface analytics. In principle, nanoparticles can be deposited on a suitable substrate from suspension or as a powder. Silicon (Si) wafers are commonly used as substrate, however, their cleaning is critical to the process. For sample preparation from suspension, we will discuss drop-casting and spin-coating, where not only the cleanliness of the substrate and purity of the suspension but also its concentration play important roles for the success of the preparation methodology. For nanoparticles with sensitive ligand shells or coatings, deposition as powders is more suitable, although this method requires particular care in fixing the sample.

A number of different procedures for preparing nanoparticles for surface analysis are presented (drop casting, spin coating, deposition from powders, and cryofixation). We discuss the challenges, opportunities, and possible applications of each method, particularly regarding the changes in the surface properties caused by the different preparation methods.

Preparazione di nanoparticelle per l'analisi ToF-SIMS e XPS

Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, ...