Attomolar Sensing Based on Liquid Interface-Assisted Surface-Enhanced Raman Scattering in Microfluidic Chip by...

Area of Science:

• Analytical Chemistry
• Nanotechnology
• Materials Science

Background:

• Surface-enhanced Raman scattering (SERS) is a powerful trace analysis technique utilizing plasmonic effects.
• Current SERS methods struggle with detecting label-free molecules below 1 nM due to the blinking SERS effect.
• SERS microfluidic chips have shown promise but require further sensitivity improvements.

Purpose of the Study:

• To develop a novel analytical strategy for achieving attomolar detection limits in SERS.
• To overcome the limitations of existing SERS techniques for label-free molecule detection.
• To introduce and validate the liquid interface-assisted SERS (LI-SERS) technique.

Main Methods:

• Fabrication of glass microfluidic chips using hybrid femtosecond (fs) laser processing.
• Implementation of fs laser-assisted chemical etching, selective metallization, and metal surface nanostructuring.
• Utilizing an analyte air-solution interface within the microfluidic channel to aggregate molecules.

Main Results:

• The novel LI-SERS technique achieved an analytical enhancement factor of 1.5 × 10^14.
• Detection limits below 10^-17 M (<10 aM) were realized for trace analysis.
• The enhancement is attributed to Marangoni convection induced by the photothermal effect at the interface.

Conclusions:

• LI-SERS significantly enhances SERS sensitivity, enabling attomolar-level detection.
• The technique effectively addresses the challenge of detecting low-concentration, label-free analytes.
• This advancement holds potential for diverse applications requiring ultra-trace analysis.