Three-Dimensional SERS Substrates Formed with Plasmonic Core-Satellite Nanostructures

Abstract

We demonstrate three-dimensional surface-enhanced Raman spectroscopy (SERS) substrates formed by accumulating plasmonic nanostructures that are synthesized using a DNA-assisted assembly method. We densely immobilize Au nanoparticles (AuNPs) on polymer beads to form core-satellite nanostructures for detecting molecules by SERS. The experimental parameters affecting the AuNP immobilization, including salt concentration and the number ratio of the AuNPs to the polymer beads, are tested to achieve a high density of the immobilized AuNPs. To create electromagnetic hot spots for sensitive SERS sensing, we add a Ag shell to the AuNPs to reduce the interparticle distance further, and we carefully adjust the thickness of the shell to optimize the SERS effects. In addition, to obtain sensitive and reproducible SERS results, instead of using the core-satellite nanostructures dispersed in solution directly, we prepare SERS substrates consisting of closely packed nanostructures by drying nanostructure-containing droplets on hydrophobic surfaces. The densely distributed small and well-controlled nanogaps on the accumulated nanostructures function as three-dimensional SERS hot spots. Our results show that the SERS spectra obtained using the substrates are much stronger and more reproducible than that obtained using the nanostructures dispersed in solution. Sensitive detection of melamine and sodium thiocyanate (NaSCN) are achieved using the SERS substrates.

3D-Printed Peptide-Hydrogel Nanoparticle Composites for Surface-Enhanced Raman Spectroscopy Sensing

“…By increasing the number of hotspots in the z-direction, the Raman signal can be increased and detection limits can be lowered. [41][42][43][44] Extrusion-based 3D printing is a direct deposition additive manufacturing approach that enables the layer-by-layer deposition of materials in x, y, and z to fabricate multilayer 3D structures. 3D printing has been used previously for the deposition of hydrogels and hydrogel-NP composites.…”

Plasmonic nanomaterial structuring for SERS enhancement

“…1, it is shown that the HCP and monolayer structures are highly targeted as the initial and fundamental roughening factors to regularly tune the SERS hotspots in the created nanogaps. 23,49 Through the proposed structure, LSPRs were synergistically created from the collective electromagnetic elds from the entire AuIoNs structure. The roughness in atomic scale as presented as single adatoms or tiny clustered adatoms prominently leads to the occurrence of a short-range chemical enhancement mechanism.…”

One-step green synthesis of antibacterial silver nanoparticles embedded in electrospun cyclodextrin nanofibers

“…7, insets). It is known that the localized surface plasmon resonance of the nanoparticles can cause strong and highly localized fields for SERS (Wu, Li, Lin, & Chen, 2017). In this context, the distribution of the Ag-NPs was explored by TEM analysis.…”