El autor agradece su fructífera discusión de este trabajo Prof. Y. Ozaki (Universidad de Kwansei Gakuin) y Dr. T. Itoh (nacional del Instituto de Ciencia Industrial avanzada y tecnología). Este trabajo fue apoyado por KAKENHI (subvenciones para investigación científica) desde el Ministerio de educación, cultura, deportes, ciencia y tecnología (no. 16K 05671).

1. preparación de la muestra
<ol><li>
Preparación de nanopartículas coloidales de plata 20<ol>
<li>Para fabricar plata coloidales nanopartículas, disolver 0,030 g de nitrato de plata y 0,030 g de citrato trisódico dihidrato en 150 mL de agua en un matraz de fondo redondo de 200 mL.</li>
		<li>Combinar el matraz con un condensador de reflujo (Dimroth).</li>
		<li>Agitar la solución en el matraz con una barra magnética de agitador y agitar. Luego, calentar la solución de agitación en el matraz en baño de aceite a 150 ° C durante 60 min. Nota: La solución convertirá luego lechoso, amarillo gris.</li>
		<li>Enfríe la suspensión a temperatura ambiente y mantener la suspensión en el frasco cubierto con papel de aluminio en el refrigerador. Nota: El protocolo puede ser una pausa en este punto. Uso de las nanopartículas coloidales, después de guardar en el refrigerador, dentro de un mes.</li>
	</ol>
</li>
	<li>
Preparación de muestra para varios colores parpadeando emisión 11<ol>
<li>Listo el portaobjetos de un microscopio, una placa de cristal con jabón de lavado a mano y enjuagar con agua.</li>
		<li>Añadir 0.1% soluciones acuosas del poly-L-lisina a la placa de cristal y retirar la solución con un soplador.</li>
		<li>Añadir la suspensión coloidal de plata a la placa de cristal y quitar la suspensión con un soplador.</li>
		<li>Incluya una zona de gota en el plato de cristal con un lápiz líquido bloqueador.</li>
		<li>Colocar agua destilada en el plato de cristal y cubrir con otra placa de vidrio para crear una diapositiva del microscopio y evitar que el agua se evapora.</li>
	</ol>
</li>
	<li>
Preparación de muestra para SERS intermitente color monótono 7 , 8 , 9 , 10<ol>
<li>Listo el portaobjetos de un microscopio, una placa de cristal con jabón de lavado a mano y enjuagar con agua.</li>
		<li>La plata coloidal suspensión la mezcla con el tinte thiacyanine o thiacarbocyanine (μm 25 ó 4, respectivamente) y una solución acuosa de NaCl (10 mM) en una proporción de volumen de 2:1:1.</li>
		<li>La suspensión de la muestra sobre la placa de vidrio de la gota y quitar la suspensión con un soplador.</li>
		<li>Incluya una zona de gota en el plato de cristal con un lápiz líquido bloqueador.</li>
		<li>La gota de una solución acuosa de NaCl (1 M) en la placa de vidrio para inmovilizar las nanopartículas de plata y cubrir con otra placa de vidrio para crear una placa portaobjetos de microscopio e impedir la evaporación de la solución.</li>
	</ol>
</li>
</ol>2. observación de centelleo nanopartículas de plata
<ol><li>
Iluminación de la muestra
	<ol>
<li>Coloque la placa de cristal de la muestra preparada con protocolo 1.2 o 1.3 en el escenario de un microscopio invertido.</li>
		<li>Iluminan la placa de vidrio la muestra utilizando luz blanca a través de un condensador de campo oscuro y un enfoque en varios puntos de color (azul, verdes, amarillos y rojos) en la placa de vidrio utilizando una lente de objetivo (60 X).</li>
		<li>Iluminan la placa de cristal de la muestra utilizando un haz atenuado, entregado en un ángulo de 30° con respecto a la superficie de la muestra, de un láser de onda continua (cw) bombeados de estado sólido (DPSS) de diodo a través de un filtro de interferencia.</li>
		<li>Para utilizar iluminación láser para observar la plata nanoaggregates como manchas de color monótonos en un mismo color, mueva el área de iluminación láser hacia el centro de la vista y centrarse en los puntos de la placa de vidrio mediante el ajuste de la etapa en la dirección z.</li>
	</ol>
</li>
	<li>
Observación de centelleo
	<ol>
<li>Inserte un filtro de paso de largo después de la lente del objetivo y se ilumina la placa de cristal de la muestra con un rayo de cw-láser DPSS entregado en un ángulo de 30° con respecto a la superficie de la muestra a través de un filtro de interferencia.</li>
		<li>Encontrar el parpadeo puntos como se muestra en la figura 1 (véase también Figura S1 en el material suplementario) moviendo el escenario en las direcciones x y y.</li>
		<li>Grabar el video de los puntos parpadeantes con el microscopio invertido, acoplado a una cámara de refrigerado digital dispositivo de carga acoplada (CCD), que tiene una resolución de tiempo de 120 61 ms, durante 20 minutos.</li>
	</ol>
</li>
</ol>3. Análisis de parpadear SERS
<ol><li>
Derivación de Perfil de tiempo de vídeo
	<ol>
<li>En el software que controla la cámara, abra el archivo de vídeo.</li>
		<li>Para seleccionar los puntos parpadeantes y zona oscura, arrastre las áreas que cubren por separado las regiones con y sin manchas en la imagen de vídeo.</li>
		<li>Para obtener perfiles de tiempo de intensidad de señal del intermitentes manchas y áreas oscuras en el video, seleccione Análisis Temporal en el análisisy haga clic en el cálculo en la ventana de Análisis Temporal .</li>
		<li>Guardar los datos como un archivo de texto.</li>
	</ol>
</li>
	<li>
Análisis del perfil de tiempo
	<ol>
<li>Acoplar una línea de base del perfil tiempo restando el perfil de tiempo de la zona oscura o ajuste con una función polinómica, como se muestra en la figuras 2A y 2B.</li>
		<li>Evaluar una intensidad promedio de la línea de base que consiste en aproximadamente 2.000 puntos, basey una desviación estándar de las intensidades de línea de base, σ, como se muestra en las figuras 2 y 2D.</li>
		<li>Distinguir eventos brillantes oscuros eventos con intensidades mayores a un umbral de base + 3σ y registrar la duración de cada evento. En la figura 3, por ejemplo, grabar el evento de 0 a 3.5476 s como el evento oscuro (con una duración de t = 3.5476 s) y grabar el evento de 3.5476 a 4.0981 s como el evento brillante (con una duración de t = 0.5505 s). Repita el procedimiento como se muestra en la tabla 1.</li>
		<li>Contar el número de acontecimientos brillantes y oscuras para cada duración, expresada en la primera y segunda línea del cuadro 2.</li>
		<li>Suma el número de eventos para cada duración, excepto para eventos de menos duración t. Como expresa en la segunda y tercera línea del cuadro 2, por ejemplo, suma el número de eventos para cada duración (excepto para los eventos de t = 0.0612 s) 41 + 18 + 9 +...; el resultado es igual a la sumatoria de t = 0.1223 s, es decir, 103.</li>
		<li>Divida las sumatorias por cada duración y normalizarlos. Tal como se expresa en la tabla 2, por ejemplo, dividir la suma de duración t = 0.0612 s por la s de duración 0.0612. El resultado es 3,351.5791. Luego, divida el resultado por el total de los resultados en la cuarta línea en la tabla 2. La distribución de probabilidad se deriva para ser 0.64494.</li>
		<li>Parcela las distribuciones de probabilidad para los eventos brillantes Pen(t) contra su duración t en un gráfico de logaritmo logaritmo y ajuste Log10Pa(t) por registro10 (<img alt="Equation 1" src="/files/ftp_upload/56729/56729eq1.jpg">) para deducir la ley exponente αen para un específico parpadeo punto. Si Pa(t) está ubicado por <img alt="Equation 1" src="/files/ftp_upload/56729/56729eq1.jpg"> </img>, la línea integral se desvía de las parcelas en pequeños valores de Pen(t), como se muestra por la línea punteada en la figura 4A.</li>
		<li>Parcela las distribuciones de probabilidad para eventos oscuro Poff(t) contra su duración t en un gráfico de logaritmo logaritmo y ajuste Log10Pde(t) por (10) registro <img alt="Equation 3" src="/files/ftp_upload/56729/56729eq3.jpg"> deducir la energía ley α exponenteoff y el truncamiento tiempo τ de la intermitencia del mismo punto. Si Poff(t) está equipado por <img alt="Equation 3" src="/files/ftp_upload/56729/56729eq3.jpg"> </img>, la curva cabida se desvía de las parcelas en pequeños valores de Pde(t).</li>
		<li>Repita 3.2.1 a 3.2.8 para los otros puntos parpadeantes en el video.</li>
	</ol>
</li>
</ol>

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El autor no tiene nada que revelar.

Desde el cruce de nanoaggregate plata, SERS se emite. Así, tenemos que preparar nanoaggregates en lugar de nanopartículas coloidales, que se cubren con aniones citrato. Agregados de plata se forman a partir de la salazón efecto creado por la adición de poly-L-lisina, NH -3+ y es el origen del SERS, o cationes de Na+ de NaCl, como se muestra en la Figura S2 del material complementario. Por otra parte, para iluminar los lugares en la zona amplia, el rayo láser desenfoc...

Superficie-realzada Raman (SERS) de dispersión es altamente sensible Espectroscopía Raman de superficie de un metal noble. Puesto que el espectro de Raman provee información detallada sobre la estructura molecular basado en las posiciones de pico agudo, a través de los modos vibracionales de grupos funcionales en las moléculas, se puede investigar la información de una sola molécula sobre una superficie de metal usando SERS1,2,3. De un nanoaggregate de plata con un adsorbato en el nivel de una sola molécula, una señal intermitente se observa1,2,3,4,5,6, 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16y el espectro oscila1,2,3,4,5,6,7,8, 9,10,11,12,13,14. Intermitente puede ser inducida por una sola molécula que se mueve al azar dentro y fuera de un campo electromagnético mejorado de (EM) en un cruce de nanoaggregate de plata de nanómetro de tamaño. Por lo tanto, parpadeando se consideran pruebas simples para la detección de una sola molécula, en comparación con una técnica usando una distribución de Poisson de intensidades SERS y un bi-analito2,3,17. Sin embargo, los mecanismos detallados del espectro intermitente y fluctuante, que puede depender fuertemente de comportamiento molecular en la superficie del Ag, son todavía controvertidos.
En estudios previos, parpadeando SERS ha sido analizado utilizando la función de autocorrelación, que puede calcular el coeficiente de difusión y concentración de moléculas en movimiento dentro y fuera de un mejorado EM campo12,13,14 . Por otra parte, una puntuación de desviación estándar normalizada, que representa la inestabilidad de la intensidad total, se ha derivado por el perfil de tiempo de la señal15. Sin embargo, estos enfoques analíticos pueden basarse en el comportamiento de algunas moléculas. En cambio, en una imagen de súper-resolución de parpadear SERS, comportamiento de una sola molécula en un campo mayor de la EM puede ser identificados16. Sin embargo, estas técnicas pueden obtener estos parámetros solamente en un campo EM mejorado. El comportamiento aleatorio de una sola molécula en un amplio rango (por ejemplo, en parpadear SERS) puede ser representado como una ley de potencia en lugar de un promedio de4,5,6,7,8 ,9,10,11, similar a la intermitente de la fluorescencia de un semiconductor único quantum dot (QD)18,19. Mediante el uso de una energía ley análisis4,5,6,7,8,9,10,11, el comportamiento molecular puede estimarse en el brillante estado (en el campo EM mayor) y estado oscuro10; es decir, se puede estimar el comportamiento de la molécula sobre toda la superficie de plata.
Para esta técnica, plata coloidales nanoaggregates son usadas4,5,6,7,8,9,10,11. Estos nanoaggregates muestran varias bandas de resonancia (LSPR) plasmones localizados que afectan fuertemente mejoradas electromagnéticas cuando son excitados en ciertas longitudes de onda. Así, inmediatamente se puede obtener plata SERS-activo existen nanopartículas en suspensión coloidal y algunos datos. En el caso de nanoestructuras simple, que tienen acuerdos, formas y tamaños específicos, la dependencia LSPR de SERS parpadear puede ocultar otras dependencias7; es decir, si se utiliza la nanoestructura a LSPR buena o mala, los parámetros será constante, y por lo tanto, se ocultarán las otras dependencias. Análisis de ley de energía se ha utilizado para descubrir varias dependencias de lo SERS intermitente de plata coloidal nanoaggregates4,5,6,7,8, 9 , 10 , 11.

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	<colgroup>
		<col />
		<col />
		<col />
		<col />
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	<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

De una sola molécula en una ensambladura de plata nanoaggregate, parpadear superficie-realzada Raman (SERS) de dispersión se observa. Aquí, se presenta un protocolo de cómo preparar el SERS-activo nanoaggregate de plata, grabar un vídeo de ciertos puntos parpadeantes en la imagen microscópica y analizar las estadísticas intermitentes. En este análisis, una ley de potencia reproduce las distribuciones de probabilidad para eventos brillantes en relación a su duración. Las distribuciones de probabilidad para los eventos oscuros están equipadas por una ley de potencia con una función exponencial. Los parámetros de la ley de energía representan el comportamiento molecular en Estados luminosos y oscuros. Se pueden estimar el modelo de paseo aleatorio y la velocidad de la molécula a través de toda la superficie de plata. Es difícil estimar aun cuando estén usando promedios, las funciones de autocorrelación y proyección de imagen de súper-resolución SERS. En el futuro, análisis de ley de energía se deben combinar con la proyección de imagen espectral, porque los orígenes de parpadear no se puede confirmar por este método de análisis solo.

De la plata nanoaggregates con poli-l-lisina preparado por protocolo 1.2, se observan manchas multicoloras parpadeantes de SERS y superficie-realzada de la fluorescencia, tal como se muestra en la figura 111. En cambio, puntos parpadeando color monótonos de SERS fueron observados para la nanoaggregates de plata con las moléculas de tinte preparadas por protocolo 1.37,8,<...

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

Este protocolo describe el análisis de parpadear Raman de superficie mejorada dispersión debido a la caminata al azar de una sola molécula sobre una superficie de plata usando leyes de la energía.

Observación y análisis de parpadear dispersión Raman de superficie mejorada

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 vistas.  Kwansei Gakuin University. Este protocolo describe el análisis de parpadear Raman de superficie mejorada dispersión debido a la caminata al azar de una sola molécula sobre una superficie de plata usando leyes de la energía.

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 basada en el filtro mejorado de Raman espectroscópico Ensayo para la detección rápida de contaminantes químicos

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

Investigación

Química

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.

Preparación de biopolímeros aerogeles el uso de disolventes verdes

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.

Medición de Tamaño de Partícula de distribución en turbias Soluciones por Dynamic Light Scattering Microscopía

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 nueva técnica para el análisis Raman de las muestras altamente radiactivo Uso de cualquier estándar micro-espectrómetro Raman

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 y métodos IR electroquímicas como herramientas para analizar compuestos orgánicos conjugados

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.

Partícula magnética de ADN vinculante el análisis por la dispersión ligera dinámica y electroforética

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.

Resolución de agua, proteínas y lípidos de In Vivo Confocal Raman Spectra de Stratum Corneum a través de un enfoque quimiométrico

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.

Aplicación de voltaje en el análisis de tamaño de partículas de dispersión de luz dinámica

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 - conjugate Systems

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.

Preparación de nanopartículas para análisis ToF-SIMS y XPS

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