Nano-Sieve-Enabled On-Chip Concentration and Multiplexed Detection of Raman-Dye-Labeled Nanocubes

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Biomedical Engineering

Background:

• Challenges in molecular detection include signal variability, low analyte abundance, and poor spectral reproducibility.
• Existing methods often lack sensitivity, stability, and multiplexing capabilities for real-time diagnostics.

Purpose of the Study:

• To engineer a portable bead-stacked nano-sieve platform for robust on-chip Raman signal amplification.
• To enhance Surface-Enhanced Raman Scattering (SERS) efficiency using functionalized silver nanocubes (AgNCs).

Main Methods:

• Integration of deformable elastomeric channels with magnetic bead stacking for AgNC immobilization.
• Creation of confined nanoscopic junctions to generate plasmonic hot-spot architectures.
• Utilizing Raman-active thiolated ligands for functionalizing AgNCs.

Main Results:

• Demonstrated substantial increases in Raman intensity for analytes like 4-mercaptobenzoic acid (4-MBA) and 4-aminothiophenol (4-ATP).
• Achieved stable enhancement factors over a four-hour operational window, outperforming off-chip assays.
• Successfully performed multiplexed sensing of mixed analytes with distinguishable spectral fingerprints under continuous-flow conditions.

Conclusions:

• The bead-stacked nano-sieve platform offers a versatile, label-free, and scalable architecture for sensitive molecular detection.
• The technology shows significant promise for real-time, non-invasive molecular surveillance and point-of-care diagnostics.
• Potential applications include early disease monitoring in resource-limited and field-deployable settings.