Silver Nanoparticle-Embedded Thin Silica-Coated Graphene Oxide as an SERS Substrate

Abstract

A hybrid of Ag nanoparticle (NP)-embedded thin silica-coated graphene oxide (GO@SiO2@Ag NPs) was prepared as a surface-enhanced Raman scattering (SERS) substrate. A 6 nm layer of silica was successfully coated on the surface of GO by the physical adsorption of sodium silicate, followed by the hydrolysis of 3-mercaptopropyl trimethoxysilane. Ag NPs were introduced onto the thin silica-coated graphene oxide by the reduction of Ag+ to prepare GO@SiO2@Ag NPs. The GO@SiO2@Ag NPs exhibited a 1.8-fold enhanced Raman signal compared to GO without a silica coating. The GO@SiO2@Ag NPs showed a detection limit of 4-mercaptobenzoic acid (4-MBA) at 0.74 μM.

Aligned diphenylalanine nanotube–silver nanoparticle templates for high‐sensitivity surface‐enhanced Raman scattering

“…SERS measurements were performed using a bespoke Raman system that consisted of an inverted optical microscope (IX71, Olympus), a monochromatic laser (HeNe, ThorLabs) with beam splitter and long pass filter (RazorEdge, Semrock), a spectrograph (SP‐2300i, Princeton Instruments), and a CCD camera (IXON, Andor) . To focus the laser (532‐nm wavelength and 5‐mW incident power), a 50× objective was used.…”

“…Such an approach is often referred to as surface‐enhanced Raman scattering (SERS), with typical enhancement factors of ~10 8 –10 10 . The ability of SERS to detect analytes (down to the single‐molecule level SERS) benefits significantly from the formation of regions with high electromagnetic field intensities (“hot spots”) such as a nanoscale (<10 nm) junction between two metal NPs . Molecules located within such hot spots experience large electromagnetic fields, resulting in a significant enhancement in the Raman signal level, with typical enhancement factors as high as ~10 14 .…”

A One-Pot Synthesis and Characterization of Antibacterial Silver Nanoparticle–Cellulose Film

“…The average size of Ag-NPs calculated by XRD patterns ( Figure 5) is larger than the average particle size of Ag-NPs in Ag-NPs/PVP solution, demonstrating that Ag-NPs continued to grow within film formation process. The -SH group in MPTS reacted with Ag to form a better bonding structure (Figure 4a), and the siloxane group of MPTS was bonded to cellulose [37,38]. The chemical bonding effect of MPTS makes cellulose and Ag-NPs more easily cross-linked.…”

Estudo de compósito formado por nanopartículas de ouro em matriz polimérica como substratos para análise SERS.

“…Assim, considerando que as nanopartículas expostas tomem um formato de meia-esferas, devem existir regiões de alta concentração de campo elétrico (hot-spots) [10,11] que favorecem o efeito SERS. No entanto, a intensificação do sinal SERS já foi observada em substratos contendo uma camada de material isolante envolvendo as nanopartículas [6][7][8][71][72][73][74], o que corrobora nossos resultados. O experimento para analisar o efeito da revelação do PMMA após a implantação de ouro foi repetido, mas utilizando-se um método diferente para a deposição do analito R6G sobre os substratos.…”

“…Tendo isto em vista, um dos principais desafios no sensoriamento químico e biológico se encontra na detecção de traços de uma dada substância (analito), podendo chegar idealmente ao regime de detecção de uma única molécula. Uma forma possível de se obter esta detecção é por meio de medidas por SERS (Surface-Enhanced Raman Spectroscopy) utilizando substratos contendo nanoestruturas metálicas [4][5][6][7][8], no caso deste trabalho, nanopartículas de ouro (AuNPs) formadas abaixo da superfície do polimetilmetacrilato (PMMA). Esta abordagem permite a formação de nanopartículas no interior do substrato e com a vantagem de protegê-las do meio ambiente, garantindo a estabilidade da camada compósita [9,10].…”