Name: Autor em destaque: Desenvolvimento e aplicação de substratos flexíveis SERS usando AgNPs sintetizados
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Description: Watch this Scientific Journal Video about Development and Application of SERS Flexible Substrates Using Synthesized AgNPs at JoVE.com

A pesquisa é apoiada pela Fundação Nacional de Ciências Naturais da China (Grant No. 61974004 e 61931018), bem como pelo National Key R&D Program of China (Grant No. 2021YFB3200100). O estudo reconhece o Laboratório de Microscopia Eletrônica da Universidade de Pequim por fornecer acesso a microscópios eletrônicos. Além disso, a pesquisa se estende graças a Ying Cui e à Escola de Ciências da Terra e do Espaço da Universidade de Pequim por sua assistência nas medições Raman.

1. Síntese de nanopartículas
<ol><li>Preparação de solução de nitrato de prata<ol><li>Usando uma balança de pesagem de precisão, meça 0,0017 g de nitrato de prata grau AR, (AgNO3, ver Tabela de Materiais) e adicione-o a 10 mL de água deionizada (DI). Agite a mistura para criar uma solução de AgNO 3 10-3 mol/L.</li>
	</ol></li>
	<li>Preparação do complexo prata-amônia<ol><li>Tomar 1 mL de água de amônia grau AR (NH3. H2</...

Fabricação de substrato flexível para detecção de SERS de R6G e tirame

<ol>
	<li>Zheng, F., Ke, W., Shi, L., Liu, H., Zhao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmonic+Au-Ag+janus+nanoparticle+engineered+ratiometric+surface-enhanced+Raman+scattering+aptasensor+for+ochratoxin+A+detection.">Plasmonic Au-Ag janus nanoparticle engineered ratiometric surface-enhanced Raman scattering aptasensor for ochratoxin A detection.</a> Analytical Chemistry. 91 (18), 11812-11820 (2019).</li><li>Zhou, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Size-tunable+gold+aerogels:+a+durable+and+misfocus-tolerant+3D+substrate+for+multiplex+SERS+detection.">Size-tunable gold aerogels: a durable and misfocus-tolerant 3D substrate for multiplex SERS detection.</a> Advanced Optical Materials. 9 (17), 2100352 (2021).</li><li>Fan, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Graphene+oxide+and+shape-controlled+silver+nanoparticle+hybrids+for+ultrasensitive+single-particle+surface-enhanced+Raman+scattering+(SERS)+sensing.">Graphene oxide and shape-controlled silver nanoparticle hybrids for ultrasensitive single-particle surface-enhanced Raman scattering (SERS) sensing.</a> Nanoscale. 6 (9), 4843-4851 (2014).</li><li>Xu, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Graphene-veiled+gold+substrate+for+surface-enhanced+Raman+spectroscopy.">Graphene-veiled gold substrate for surface-enhanced Raman spectroscopy.</a> Advanced Materials. 25 (6), 928-933 (2013).</li><li>Li, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Graphene-coated+Si+nanowires+as+substrates+for+surface-enhanced+Raman+scattering.">Graphene-coated Si nanowires as substrates for surface-enhanced Raman scattering.</a> Applied Surface Science. 541, 0169-4332 (2021).</li><li>Chin, C. 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Neste estudo, foi introduzido um substrato SERS flexível, que ligou AgNPs ao PDMS através de modificação química e obteve excelente desempenho. Durante a síntese de partículas, especificamente na síntese do complexo amônia de prata (etapa 1.2), a cor da solução desempenha um papel crucial. A adição de muita água de amônia em gotas pode afetar adversamente a qualidade da síntese de AgNPs, potencialmente levando a resultados de detecção malsucedidos. Deve-se atentar para a modificação do substrato (etap...

O espalhamento Raman aprimorado por superfície (SERS), como um tipo de espalhamento Raman, oferece as vantagens de alta sensibilidade e condições de detecção suaves, podendo até mesmo alcançar a detecção de uma única molécula 1,2,3,4. Nanoestruturas metálicas, como ouro e prata, são tipicamente usadas como substratos SERS para permitir a detecção de substâncias 5,6. O aprimoramento do acoplamento eletromagnético em superfícies nanoestruturadas desempenha um papel significativo em aplicações de SERS. Nanoestruturas metálicas com tamanhos, formas, distâncias interpartículas e composições variadas podem se agregar para criar inúmeros "hotspots" gerando intensos campos eletromagnéticos devido a ressonâncias localizadas de plásmons de superfície 7,8. Muitos estudos têm desenvolvido nanopartículas metálicas com diferentes morfologias como substratos do SERS, demonstrando sua eficácia na obtenção do realce do SERS 9,10.
Substratos SERS flexíveis encontram amplas aplicações, com nanoestruturas capazes de produzir efeitos SERS depositados em substratos flexíveis para facilitar a detecção direta em superfícies curvas. Substratos flexíveis SERS são empregados para detectar e coletar analitos em superfícies irregulares, não planas ou curvas. Os substratos flexíveis SERS comuns incluem fibras, filmes poliméricos e filmes de óxido de grafeno11,12,13,14. Dentre eles, o polidimetilsiloxano (PDMS) é um dos materiais poliméricos mais utilizados e oferece vantagens como alta transparência, alta resistência à tração, estabilidade química, não toxicidade e adesão15,16,17. O PDMS tem uma baixa seção Raman transversal, tornando seu impacto sobre o sinal Raman insignificante18. Como o pré-polímero PDMS está na forma líquida, ele pode ser curado por calor ou luz, proporcionando um alto grau de controlabilidade e conveniência. Substratos SERS baseados em PDMS são substratos SERS flexíveis relativamente comuns, tendo sido utilizados em estudos anteriores para incorporar várias nanopartículas metálicas para detecção de diferentes substâncias bioquímicas com desempenho exemplar19,20.
Na preparação de substratos SERS, a fabricação de estruturas nanogap é crucial. A tecnologia de deposição física oferece vantagens como alta escalabilidade, uniformidade e reprodutibilidade, mas normalmente requer boas condições de vácuo e equipamentos especializados, limitando suas aplicações práticas21. Além disso, a fabricação de nanoestruturas em escala de poucos nanômetros permanece desafiadora com as técnicas convencionais de deposição22. Consequentemente, nanopartículas sintetizadas através de métodos químicos podem ser adsorvidas em filmes transparentes flexíveis através de várias interações, facilitando a auto-montagem de estruturas metálicas na nanoescala. Para garantir o sucesso da adsorção, as interações podem ser ajustadas modificando física ou quimicamente a superfície do filme para alterar sua hidrofilicidade superficial23. As nanopartículas de prata, em comparação com as nanopartículas de ouro, exibem melhor desempenho do SERS, mas sua instabilidade, particularmente sua suscetibilidade à oxidação no ar, resulta em uma rápida diminuição do SERS Enhancement Factor (EF), afetando o desempenho do substrato24. Assim, é essencial desenvolver um método de partículas estáveis.
A presença de resíduos de agrotóxicos tem atraído atenção significativa, criando uma necessidade premente de métodos robustos capazes de detectar e identificar rapidamente várias classes de produtos químicos perigosos em alimentos no campo25,26. Os substratos flexíveis SERS oferecem vantagens únicas em aplicações práticas, particularmente no domínio da segurança alimentar. Este artigo apresenta um método para preparar um substrato flexível SERS através da ligação de nanopartículas de prata revestidas com glicose sintetizadas (AgNPs) em um substrato PDMS (Figura 1). A presença de glicose protege as AgNPs, atenuando a oxidação da prata no ar. O substrato demonstra excelente desempenho de detecção, capaz de detectar Rodamina 6G (R6G) tão baixa quanto 10-10 M e pesticida Thiram tão baixo quanto 10-8 M, com boa uniformidade. Além disso, o substrato flexível pode ser empregado para detecção através de colagem e amostragem, com inúmeros cenários potenciais de aplicação.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Ammonia (NH3.H2O, 25%)</td>
			<td>Beijing Chemical Works</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>APTES (98%)</td>
			<td>Beyotime</td>
			<td>ST1087</td>
			<td></td>
		</tr>
		<tr>
			<td>BD-20AC Laboratory Chrona Treater</td>
			<td>Electro-Technic Products Inc.</td>
			<td>12051A</td>
			<td></td>
		</tr>
		<tr>
			<td>D-glucose</td>
			<td>Beijing Chemical Works</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Environmental Scanning electron microscope (ESEM)</td>
			<td>FEI</td>
			<td>QUANTA 250</td>
			<td></td>
		</tr>
		<tr>
			<td>Raman microscope</td>
			<td>Horiba JY</td>
			<td>LabRAM HR Evolution</td>
			<td></td>
		</tr>
		<tr>
			<td>Rhodamine 6G</td>
			<td>Beijing Chemical Works</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Silicone Elastomer Base and Silicone Elastomer Curing Agent</td>
			<td>Dow Corning Corporation</td>
			<td>SYLGARD 184</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver nitrate</td>
			<td>Beijing Chemical Works</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Thiram (C6H12N2S2, 99.9%)</td>
			<td>Beijing Chemical Works</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of polydimethylsiloxane (pdms)-based flexible surface-enhanced raman scattering (sers) substrate for ultrasensitive detection

Este artigo apresenta um método de fabricação de um substrato flexível projetado para espalhamento Raman Intensificado por Superfície (SERS). Nanopartículas de prata (AgNPs) foram sintetizadas através de uma reação de complexação envolvendo nitrato de prata (AgNO3) e amônia, seguida de redução usando glicose. As AgNPs resultantes exibiram uma distribuição de tamanho uniforme variando de 20 nm a 50 nm. Posteriormente, 3-aminopropiltrietoxisilano (APTES) foi empregado para modificar um substrato de PDMS que havia sido tratado superficialmente com plasma de oxigênio. Esse processo facilitou a automontagem das AgNPs no substrato. Uma avaliação sistemática do impacto de várias condições experimentais no desempenho do substrato levou ao desenvolvimento de um substrato SERS com excelente desempenho e um Enhanced Factor (EF). Utilizando este substrato, foram alcançados impressionantes limites de detecção de 10-10 M para R6G (Rodamina 6G) e 10-8 M para Thiram. O substrato foi empregado com sucesso na detecção de resíduos de agrotóxicos em maçãs, com resultados altamente satisfatórios. O substrato flexível SERS demonstra grande potencial para aplicações no mundo real, incluindo detecção em cenários complexos.

Surface-Enhanced Raman Scattering (SERS), as a type of Raman scattering, offers the advantages of high sensitivity and gentle detection conditions, and can even achieve single molecule detection1,2,3,4. Metal nanostructures, such as gold and silver, are typically used as SERS substrates to enable substance detection5,6. Electromagnetic coupling enhancement on nanostructured surfaces plays a significant role in SERS applications. Metallic nanostructures with varying sizes, shapes, interparticle distances, and compositions can aggregate to create numerous &#34;hotspots&#34; generating intense electromagnetic fields due to localized surface plasmon resonances7,8. Many studies have developed metal nanoparticles with different morphologies as SERS substrates, demonstrating their effectiveness in achieving SERS enhancement9,10.
Flexible SERS substrates find wide applications, with nanostructures capable of producing SERS effects deposited on flexible substrates to facilitate direct detection on curved surfaces. Flexible SERS substrates are employed for detecting and collecting analytes on irregular, non-planar, or curved surfaces. Common flexible SERS substrates include fibers, polymer films, and graphene oxide films11,12,13,14. Among them, polydimethylsiloxane (PDMS) is one of the most widely used polymer materials and offers advantages such as high transparency, high tensile strength, chemical stability, non-toxicity, and adhesion15,16,17. PDMS has a low Raman cross-section, making its impact on the Raman signal negligible18. Since the PDMS prepolymer is in liquid form, it can be cured by heat or light, providing a high degree of controllability and convenience. PDMS-based SERS substrates are relatively common flexible SERS substrates, having been used in previous studies to embed various metal nanoparticles for detecting different biochemical substances with exemplary performance19,20.
In the preparation of SERS substrates, the fabrication of nanogap structures is crucial. Physical deposition technology offers advantages like high scalability, uniformity, and reproducibility but typically requires good vacuum conditions and specialized equipment, limiting its practical applications21. Additionally, fabricating nanostructures at the few-nanometer scale remains challenging with conventional deposition techniques22. Consequently, nanoparticles synthesized through chemical methods can be adsorbed onto flexible transparent films through various interactions, facilitating the self-assembly of metallic structures at the nanoscale. To ensure successful adsorption, interactions can be adjusted by physically or chemically modifying the film surface to alter its surface hydrophilicity23. Silver nanoparticles, compared to gold nanoparticles, exhibit better SERS performance, but their instability, particularly their susceptibility to oxidation in air, results in a rapid decrease in the SERS Enhancement Factor (EF), affecting substrate performance24. Hence, it is essential to develop a stable particle method.
The presence of pesticide residues has garnered significant attention, creating a pressing need for robust methods capable of rapidly detecting and identifying various classes of hazardous chemicals in food in the field25,26. Flexible SERS substrates offer unique advantages in practical applications, particularly in the realm of food safety. This article introduces a method for preparing a flexible SERS substrate by bonding synthesized glucose-coated silver nanoparticles (AgNPs) onto a PDMS substrate (Figure 1). The presence of glucose protects the AgNPs, mitigating silver oxidation in the air. The substrate demonstrates excellent detection performance, capable of detecting Rhodamine 6G (R6G) as low as 10-10 M and pesticide Thiram as low as 10-8 M, with good uniformity. Moreover, the flexible substrate can be employed for detection through bonding and sampling, with numerous potential application scenarios.

Autor em destaque: Desenvolvimento e aplicação de substratos flexíveis SERS usando AgNPs sintetizados 

Fabricação de substrato Raman Flexível Surface-Enhanced Raman (SERS) à base de polidimetilsiloxano (PDMS) para detecção ultrassensível

This protocol describes preparing SERS flexible substrates, applying them to actual detection scenarios. The SERS flexible substrate offered by this protocol is environmental friendly and achieves good detection performance. The silver nanoparticles can be synthesized easily by simple vessels, and do not require complicated experimental conditions and environment.In our laboratory, we plan to focus on researching the silver nanoparticles synthesized through the vessel used in this study. We'll explore methods to enhance their SERS detection capabilities, and leverage their unique properties and characteristics to design better performing SERS detection substrates.

Neste estudo, um substrato flexível SERS composto por AgNPs sintéticas envoltas em glicose e auto-montadas em PDMS usando APTES foi desenvolvido, alcançando excelente desempenho de detecção para aplicações práticas de detecção de pesticidas. Os limites de detecção para R6G e Thiram foram atingidos em 10-10 M e 10-8 M, respectivamente, com um Enhancement Factor (EF) de 1 x 10 5. Além disso, o substrato demonstrou uniformidade.
As AgNPs envoltas em g...

Watch this Scientific Journal Video about Development and Application of SERS Flexible Substrates Using Synthesized AgNPs at JoVE.com

Este protocolo descreve um método de fabricação de um substrato flexível para espalhamento Raman intensificado por superfície. Este método tem sido utilizado na detecção bem sucedida de baixas concentrações de R6G e Thiram.

This article presents a fabrication method for a flexible substrate designed for Surface-Enhanced Raman Scattering (SERS). Silver nanoparticles (AgNPs) ...

Este protocolo descreve a preparação de substratos flexíveis SERS, aplicando-os a cenários reais de detecção. O substrato flexível SERS oferecido por este protocolo é ambientalmente amigável e alcança um bom desempenho de detecção. As nanopartículas de prata podem ser sintetizadas facilmente por vasos simples, e não requerem condições experimentais complicadas e ambiente.Em nosso laboratório, pretendemos focar na pesquisa das nanopartículas de prata sintetizadas através do vaso utilizado neste estudo. Exploraremos métodos para aprimorar seus recursos de detecção de SERS e aproveitaremos suas propriedades e características exclusivas para projetar substratos de detecção SERS de melhor desempenho.

fabrication-polydimethylsiloxane-pdms-based-flexible-surface-enhanced

Research

JoVE Journal

Engineering

Fabrication of polydimethylsiloxane (PDMS)-Based Flexible Surface-Enhanced Raman Scattering (SERS) Substrate for Ultrasensitive Detection

This article presents a fabrication method for a flexible substrate designed for Surface-Enhanced Raman Scattering (SERS). Silver nanoparticles (AgNPs) were synthesized through a complexation reaction involving silver nitrate (AgNO3) and ammonia, followed by reduction using glucose. The resulting AgNPs exhibited a uniform size distribution ranging from 20 nm to 50 nm. Subsequently, 3-aminopropyl triethoxysilane (APTES) was employed to modify a PDMS substrate that had been surface-treated with oxygen plasma. This process facilitated the self-assembly of AgNPs onto the substrate. A systematic evaluation of the impact of various experimental conditions on substrate performance led to the development of a SERS substrate with excellent performance and an Enhanced Factor (EF). Utilizing this substrate, impressive detection limits of 10-10 M for R6G (Rhodamine 6G) and 10-8 M for Thiram were achieved. The substrate was successfully employed for detecting pesticide residues on apples, yielding highly satisfactory results. The flexible SERS substrate demonstrates great potential for real-world applications, including detection in complex scenarios.

This protocol describes a fabrication method for a flexible substrate for surface-enhanced Raman scattering. This method has been used in the successful detection of low concentrations of R6G and Thiram.

Engenharia

Synthesis of Silver Nanoparticles and Preparation of Flexible SERS Detection Substrate

To prepare silver nitrate solution, measure 0.0017 grams of AR grade silver nitrate on a weighing balance. Add the weighed powder to 10 milliliters of deionized water and stir the mixture. Draw one milliliter of AR grade ammonia water using a syringe and add it to the silver nitrate solution while stirring, until the solution becomes clear.To prepare 0.2 molar glucose solution, weigh 0.36 grams of glucose powder and add it to 10 milliliters of deionized water. Stir the mixture thoroughly. Next, using a pipette gun, add 30 microliters of the silver ammonia complex into the glucose solution at 30 minute intervals.To synthesize yellow colored silver nanoparticles. To synthesize the PDMS substrate, take five grams of PDMS A solution and add B solution into it, at a ratio of one to 10. Stir the mixture thoroughly.Transfer the mixed PDMS into a square Petri dish and bake it in an 80 degree Celsius oven for two hours. Once cured, use a scalpel to cut the PDMS along the dark grid of the dish, creating small cubes. Next, move the handheld plasma processor back and forth over the PDMS piece for surface plasma treatment.For APTES modification, immerse the surface modified PDMS pieces into 10%APTES solution for 10 hours. Finally, immerse the PDMS substrate into the silver nanoparticle solution for 10 hours. ESEM images showed uniformity in synthesized nanoparticles with diameters between 20 and 50 nanometers.The Surface-Enhanced Raman Scattering signals for fabricated PDMS substrates displayed excellent detection capability, reaching a limit of 10 to the negative 10th molar for R6G with notable enhancement effect. The substrate also showed Thiram detection with clear characteristic peaks, up to 10 to the minus eighth molar. The paste and peel method on the apple surface show the detection of Thiram up to 10 to the minus seventh molar, indicating the effectiveness of the substrate for identifying pesticide residues on fruit surfaces.