O autor agradece a Prof Y. Ozaki (Kwansei Gakuin University) e Dr. T. Itoh (National Institute of Advanced Industrial Science e Technology) para sua discussão proveitosa deste trabalho. Este trabalho foi financiado pelo KAKENHI (subsídio para C de investigação científica) do Ministério da educação, cultura, esportes, ciência e tecnologia (n º 16K. 05671).

1. preparação da amostra
<ol><li>
Preparação de nanopartículas de prata coloidais 20<ol>
<li>Para fabricar a nanopartículas de prata coloidais, dissolva 0,030 g de nitrato de prata e 0,030 g de citrato trissódico dihidratado em 150 mL de água num balão de fundo redondo de 200 mL.</li>
		<li>Combine o balão com um condensador de refluxo (Dimroth).</li>
		<li>Misture a solução do frasco com uma barra magnética de agitador e mexa. Em seguida, aqueça a solução agita o balão em banho de óleo a 150 ° C por 60 min. Nota: A solução vai virar cinza amarela, então leitosa.</li>
		<li>Arrefecer a suspensão em temperatura ambiente e manter a suspensão no frasco coberto com folha de alumínio em um frigorífico. Nota: O protocolo pode ser interrompido neste ponto. Use as nanopartículas coloidais, depois armazenar no frigorífico, dentro de um mês.</li>
	</ol>
</li>
	<li>
Preparação da amostra para multi-coloridas piscando de emissão 11<ol>
<li>Para preparar uma lâmina de microscópio, lave à mão uma placa de vidro com sabão e enxágue com água.</li>
		<li>Adicionar 0,1% solução aquosa de poli-L-lisina para a placa de vidro e remover a solução com um ventilador.</li>
		<li>Adicionar a suspensão coloidal de prata para a placa de vidro e remover a suspensão com um ventilador.</li>
		<li>Coloque uma área para soltar a placa de vidro com uma caneta de bloqueador líquido.</li>
		<li>Gota de água destilada na placa de vidro e cubra-o com outra placa de vidro para criar um slide de microscópio e evitar que a água evapora.</li>
	</ol>
</li>
	<li>
Preparação da amostra para monótonos coloridas piscando SERS 7 , 8 , 9 , 10<ol>
<li>Para preparar uma lâmina de microscópio, lave à mão uma placa de vidro com sabão e enxágue com água.</li>
		<li>Misturar a suspensão coloidal de prata com tintura de thiacyanine ou thiacarbocyanine (µM 25 ou 4, respectivamente) e uma solução aquosa de NaCl (10 mM) em uma relação de volume de 2:1:1.</li>
		<li>Deixar a suspensão da amostra na placa de vidro e remover a suspensão com um ventilador.</li>
		<li>Coloque uma área para soltar a placa de vidro com uma caneta de bloqueador líquido.</li>
		<li>Gota de solução aquosa de NaCl (1 M) na placa de vidro para imobilizar as nanopartículas de prata e cubra-o com outra placa de vidro para criar um prato de corrediça do microscópio e impedir a evaporação da solução.</li>
	</ol>
</li>
</ol>2. observação de nanopartículas de prata a piscar
<ol><li>
Iluminação da amostra
	<ol>
<li>Coloque a placa de vidro de amostra preparada usando protocolo 1.2 ou 1.3 no palco de um microscópio invertido.</li>
		<li>Ilumine a placa de vidro de amostra usando luz branca através de um condensador de campo escuro e foco em vários pontos coloridos (azuis, verdes, amarelos e vermelhos) na placa de vidro, usando uma lente objetiva (60 X).</li>
		<li>Ilumine a placa de vidro de amostra utilizando um feixe atenuado, entregado a um ângulo de 30° em relação à superfície da amostra, de um laser de assemelhace (cw) diodo bombeado de estado sólido (DPSS) através de um filtro de interferência.</li>
		<li>Para usar iluminação laser para observar a nanoaggregates de prata como monótonas manchas coloridas em uma envolvente da mesma cor, mover a área de iluminação do laser para o centro da vista e focalizar os pontos na placa de vidro, ajustando o estágio na direção z.</li>
	</ol>
</li>
	<li>
Observação de piscar
	<ol>
<li>Inserir um filtro de passa-tempo após a lente objetiva e iluminam a placa de vidro de amostra usando um feixe de cw-laser DPSS entregado a um ângulo de 30° em relação à superfície da amostra através de um filtro de interferência.</li>
		<li>Encontrar a piscar pontos conforme mostrado na Figura 1 (ver também Figura S1 no material complementar) movendo o palco na x - e y-direções.</li>
		<li>Gravar vídeo dos pontos piscando com o microscópio invertido, acoplado a uma câmera de refrigeração digital dispositivo de carga acoplada (CCD), que tem uma resolução de tempo de 61-120 ms, por 20 min.</li>
	</ol>
</li>
</ol>3. análise de piscar SERS
<ol><li>
Derivação do perfil do tempo de vídeo
	<ol>
<li>No software que controla a câmera CCD, abra o arquivo de vídeo.</li>
		<li>Para selecionar os pontos piscando e área escura, arraste áreas que cobrem separadamente as regiões com e sem manchas na imagem de vídeo.</li>
		<li>Para derivar perfis de tempo de intensidade de sinal o pontos piscando e áreas escuras no vídeo, selecione Análise Temporal em análisee clique a calcular na janela de Análise Temporal .</li>
		<li>Salve os dados como um arquivo de texto.</li>
	</ol>
</li>
	<li>
Análise do perfil do tempo
	<ol>
<li>Achate uma linha de base do perfil tempo subtraindo-se o perfil de tempo do área escura e/ou montagem com uma função polinomial, como mostrado nas figuras 2A e 2B.</li>
		<li>Avalie uma intensidade média de base que consiste em aproximadamente 2000 pontos, eubasee um desvio-padrão das intensidades de linha de base, σ, como mostrado nas figuras 2 e 2D.</li>
		<li>Distinguir eventos brilhantes de acontecimentos sinistros usando intensidades maiores do que um limiar de eubase + 3σ e registar a duração de cada evento. Na Figura 3, por exemplo, registrar o evento de 0 para 3.5476 s como o evento escuro (com uma duração de t = 3.5476 s) e registrar o evento de 3.5476 para 4.0981 s como o evento brilhante (com uma duração de t = 0.5505 s). Repita o procedimento como mostrado na tabela 1.</li>
		<li>Conte o número de eventos brilhantes e escuros para cada duração, tal como expresso nas primeiras e segunda linhas da tabela 2.</li>
		<li>Soma do número de eventos para cada duração, exceto para eventos mais curtos do que a duração t. Conforme expresso nas segunda e terceiros linhas da tabela 2, por exemplo, somar o número de eventos para cada duração (excepto os eventos para t = 0.0612 s) como 41 + 18 + 9 +...; o resultado é igual a soma de t = 0.1223 s, ou seja, 103.</li>
		<li>Divida os somatórios por cada duração e normalizá-los. Conforme expresso na tabela 2, por exemplo, dividir o somatório para duração t = 0.0612 s pela duração 0.0612 s. O resultado é 3,351.5791. Em seguida, divida o resultado pelo total dos resultados na quarta linha da tabela 2. A distribuição de probabilidade é derivada para ser 0.64494.</li>
		<li>Plotar as distribuições de probabilidade para o brilhante eventos Pem(t) contra sua duração t em um gráfico do logaritmo-logaritmo e caber Log10Pem(t) pelo Log10 (<img alt="Equation 1" src="/files/ftp_upload/56729/56729eq1.jpg">) para deduzir o poder lei expoente α para um determinado ponto a piscar. Se Pem(t) é montado por <img alt="Equation 1" src="/files/ftp_upload/56729/56729eq1.jpg"> </img>, a linha cabida se desvia as parcelas em valores pequenos de Pem(t), como mostrado pela linha pontilhada na Figura 4A.</li>
		<li>Plotar as distribuições de probabilidade para eventos escuro Pfora(t) contra sua duração t em um gráfico do logaritmo-logaritmo e apto Log10Pfora(t) por Log10( <img alt="Equation 3" src="/files/ftp_upload/56729/56729eq3.jpg"> a deduzir a energia lei expoente αfora e o truncamento de tempo τ a piscar mesmo local. Se Pfora(t) é montado por <img alt="Equation 3" src="/files/ftp_upload/56729/56729eq3.jpg"> </img>, a cabido curva desvia as parcelas em valores pequenos de Pfora(t).</li>
		<li>Repita 3.2.1 para 3.2.8 para os outros pontos piscando no vídeo.</li>
	</ol>
</li>
</ol>

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O autor não tem nada para divulgar.

Da junção da prata nanoaggregate, SERS é emitido. Assim, precisamos preparar nanoaggregates ao invés de nanopartículas coloidais, que são cobertas com ânions de citrato. Agregados de prata são formados a partir a salgar-para fora o efeito criado pela adição de poli-L-lisina, que tem -NH3+ e é a origem dos SERS, ou cátions at+ de NaCl, conforme mostrado na Figura S2 do material complementar. Além disso, para iluminar os muitos locais na área ampla, o feixe de...

Superfície-enhanced Raman espalhamento (SERS) é altamente sensível Espectroscopia Raman de uma superfície de metal nobre. Desde que o espectro Raman fornece informações detalhadas sobre a estrutura molecular com base nas posições do pico afiado, através dos modos vibracionais dos grupos funcionais nas moléculas, as informações de uma única molécula sobre uma superfície metálica podem ser investigadas usando SERS1,2,3. De um nanoaggregate de prata com um adsorbate no nível do único-molécula, um sinal intermitente é observado1,2,3,4,5,6, 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16e o espectro varia1,2,3,4,5,6,7,8, 9,10,11,12,13,14. Piscando pode ser induzida por uma única molécula que aleatoriamente se move dentro e fora de um campo de (EM) eletromagnético melhorado em uma junção de nanoaggregate prata nanômetros de tamanho. Portanto, piscando é considerada uma prova simples para a deteção de único-molécula, comparada com uma técnica usando uma distribuição de Poisson de intensidades SERS e um bi-analito2,3,17. No entanto, os mecanismos detalhados do espectro piscando e flutuante, que pode depender fortemente de comportamento molecular na superfície Ag, são ainda controversos.
Em estudos anteriores, piscar SERS foi analisada usando a função de autocorrelação, que pode calcular o coeficiente de difusão e concentração de moléculas entrando e um reforço EM campo12,13,14 . Além disso, uma pontuação normalizada desvio-padrão, que representa a instabilidade na intensidade total, foram obtida a partir do perfil de tempo do sinal15. No entanto, essas abordagens analíticas podem basear-se sobre o comportamento de algumas moléculas. Em contraste, em uma imagem de super-resolução de piscar SERS, comportamento único-molécula em um campo EM avançado pode ser identificados16. No entanto, essas técnicas podem obter tais parâmetros somente em um campo EM reforçada. O comportamento aleatório de uma única molécula dentro de uma grande variedade (por exemplo, no piscar SERS) pode ser representado como uma lei de potência, ao invés de uma média de4,5,6,7,8 ,9,10,11, semelhante à fluorescência pisca de um único semicondutor quantum dot (QD)18,19. Usando um poder lei análise4,5,6,7,8,9,10,11, comportamento molecular pode ser estimado no estado brilhante (no campo EM reforçada) e no estado escuro10; ou seja, o comportamento da molécula sobre toda a superfície de prata pode ser estimado.
Para esta técnica, a prata coloidais nanoaggregates são usados4,5,6,7,8,9,10,11. Estes nanoaggregates mostrar várias bandas de ressonância (LECC) de plasmon de superfície localizadas que afetam fortemente reforçada de campos eletromagnéticos quando eles estão animados em certos comprimentos de onda. Assim, prata SERS-ativo nanopartículas existem em suspensão coloidal e alguns dados pode ser obtida imediatamente. No caso de nanoestruturas simples, que têm regimes, formas e tamanhos específicos, a dependência de LECC de SERS piscando pode esconder outras dependências7; ou seja, se o bom ou mau nanostructure de LECC é usado, os parâmetros será constantes, e outras dependências, portanto, ficará oculta. Análise de lei do poder tem sido usado para descobrir várias dependências dos SERS piscando de prata coloidal nanoaggregates4,5,6,7,8, 9 , 10 , 11.

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		<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

De uma única molécula em uma junção de prata nanoaggregate, piscar superfície-enhanced Raman espalhamento (SERS) é observada. Aqui, um protocolo é apresentado em como preparar o SERS-ativo nanoaggregate de prata, gravar um vídeo de determinados pontos piscando em imagem microscópica e analisar as estatísticas pisca. Nesta análise, uma lei de potência reproduz as distribuições de probabilidade para eventos brilhantes em relação a sua duração. As distribuições de probabilidade para eventos escuros são montadas por uma lei de potência com uma função exponencial. Os parâmetros da lei poder representam o comportamento molecular nos Estados brilhantes e escuros. O modelo de passeio aleatório e a velocidade da molécula através de toda a superfície de prata podem ser estimados. É difícil de estimar, mesmo quando usando as médias, funções de autocorrelação e imagem latente de super-resolução SERS. No futuro, análises de lei de poder devem ser combinadas com imagem espectral, porque as origens de piscar não podem ser confirmadas por este método de análise sozinho.

Do nanoaggregates prata com poli-L-lisina, preparado pelo Protocolo 1.2, multicoloridos pontos piscando de SERS e fluorescência avançada superfície são observados, como mostrado na Figura 111. Em contraste, monótonos pontos piscando coloridos de SERS foram observados para a nanoaggregates de prata com as moléculas de corante preparadas pelo Protocolo 1.37,8,<su...

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 descreve a análise de superfície-enhanced Raman a piscar espalhamento devido o passeio aleatório de uma única molécula em uma superfície de prata usando as leis do poder.

Observação e Análise da Espalhamento Raman Aprimorado por Superfície do Piscar de Olhos.

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

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7.3K visualizações.  Kwansei Gakuin University. Este protocolo descreve a análise de superfície-enhanced Raman a piscar espalhamento devido o passeio aleatório de uma única molécula em uma superfície de prata usando as leis do poder.

Vídeo: 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.

A superfície à base de filtro avançado Raman espectroscópica Ensaio para a rápida detecção 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 ...

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.

Preparação de Biopolymer Aerogels utilizando solventes 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.

Medição do Tamanho de Partículas Distribuição em turvas Solutions pela Dynamic dispersão de luz 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.

Uma nova técnica de Análise de Raman de amostras altamente radioativo Usando qualquer padrão Micro-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 e IR Spectroelectrochemical métodos como ferramentas para analisar compostos orgânicos 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.

DNA-magnético partícula análise por dispersão de luz dinâmica e eletroforético de vinculação

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.

Resolvendo água, proteínas e lipídeos de in vivo confocal Raman Spectra de stratum corneum através de uma abordagem quimiométrica

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.

Aplicação da tensão na análise dinâmica do tamanho da partícula de dispersão de luz

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.

Mediçãos de Raman estimuladas do tempo ultrarrápido de sistemas funcionais de πconjugados

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.

Preparação de nanopartículas para Análise ToF-SIMS e XPS

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