Electric-Field Enhanced Molecule Detection in Suspension on Assembled Plasmonic Arrays by Raman Spectroscopy

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) is crucial for ultrasensitive detection of biochemicals in suspension.
• A key challenge is achieving high sensitivity and reproducibility in SERS sensing directly from liquid samples.

Purpose of the Study:

• To develop a novel SERS sensing platform using nanocapsules with uniformly distributed silver nanoparticles (Ag NPs).
• To investigate the dual role of these nanostructures in focusing molecules and enhancing SERS signals using electric fields.

Main Methods:

• Strategically designed longitudinal nanocapsule structures with uniformly surface-distributed Ag NPs were synthesized.
• Optimized reaction conditions ensured uniform Ag NP size and junction formation for reproducible detection.
• Electric fields were applied to induce electrokinetic effects for molecule concentration.

Main Results:

• The nanocapsule platform demonstrated enhanced SERS sensitivity for detecting Nile blue molecules.
• A significant signal enhancement of 34.4±3.1% was achieved at optimal alternating current (AC) frequencies and voltages.
• The results highlight the dual functionality of plasmonic nanoparticles for both molecule concentration and detection.

Conclusions:

• The developed nanocapsule-based SERS system offers a promising approach for ultrasensitive detection of analytes in suspension.
• The combined effects of plasmonic enhancement and electric-field-induced molecule concentration lead to improved SERS sensitivity.
• This work provides a foundation for new Raman sensing devices applicable in microfluidics and biochemical analysis.