Surface-enhanced Raman spectroscopy method for active capture of targets by interlayer small-gap hot spot structures

Area of Science:

• Analytical Chemistry
• Materials Science
• Nanotechnology

Background:

• Surface-enhanced Raman scattering (SERS) offers high sensitivity for analytical detection.
• Practical SERS applications are limited by precise control over hot spots and molecule localization.
• Silver nanoparticles (AgNPs) are key components in SERS substrate design.

Purpose of the Study:

• To develop a novel SERS substrate with enhanced sensitivity and precise hot spot control.
• To investigate the electromagnetic field enhancement in nanogap structures for SERS.
• To demonstrate the application of the developed SERS substrate for detecting target molecules and antibiotic residues.

Main Methods:

• Fabrication of a novel AgNP/AgNP structure using a liquid-liquid interface self-assembly method.
• Insertion of a single layer of tungsten disulfide (WS2) as a sub-nanometer spacer between AgNP layers.
• Utilizing the Raman signal of WS2 to study electromagnetic field enhancement.
• Employing finite element theoretical simulations to confirm experimental results.
• Testing the substrate for SERS detection of various target molecules and antibiotic residues in poultry feathers.

Main Results:

• The novel AgNP/AgNP structure generated a large number of interlayer nanogap structures.
• A significant SERS enhancement factor of 9.72 × 10^4 was achieved due to plasmon coupling between AgNP layers with WS2 as a spacer.
• The enhancement factor was substantially higher compared to WS2 on a single AgNP layer.
• Highly sensitive SERS detection of various target molecules was demonstrated.
• Successful application for detecting antibiotic residues in poultry feathers was achieved.

Conclusions:

• The proposed interlayer small-gap structure provides a new strategy for high-performance SERS substrate construction.
• The developed SERS substrate exhibits strong near-field enhancement originating from plasmon coupling.
• This approach is promising for advancing practical SERS applications in food safety monitoring and environmental detection.