Size-controllable colloidal Ag nano-aggregates with long-time SERS detection window for on-line high-throughput...

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Surface-enhanced Raman scattering (SERS) relies on metal nanoparticle aggregates to create 'hot spots' for enhanced signal.
• Existing methods for creating aggregates often use reagents that compromise metal surface properties, affecting SERS performance.
• Stable, controllable nano-aggregates are crucial for reliable and sensitive SERS applications.

Purpose of the Study:

• To develop a new method for synthesizing stable silver nano-aggregates (AgNAs) with controllable sizes.
• To evaluate the SERS performance, stability, and detection window of the synthesized AgNAs.
• To establish a microfluidic-based platform for high-throughput, on-line SERS detection using the AgNAs.

Main Methods:

• A
• freeze-thaw-ultrasonication
• method was employed to synthesize stable colloidal Ag nano-aggregates (AgNAs).

Main Results:

• The synthesized AgNAs exhibited controllable sizes and remained stable for several days.
• The AgNAs maintained metal surface charges and adsorption affinity, leading to excellent SERS stability and sensitivity.
• A SERS detection window exceeding 25 minutes was achieved, suitable for long-term monitoring.
• A microfluidic device integrated with AgNAs enabled sequential on-line continuous detection for high-throughput analysis.
• The platform successfully monitored UV-Fenton degradation of methylene blue (MB) and detected 5-nitro-8-hydroxyquinoline (5-NQ).

Conclusions:

• The
• freeze-thaw-ultrasonication
• method provides a robust approach for generating stable AgNAs for SERS.
• The developed microfluidic SERS platform facilitates sensitive, high-throughput analysis, applicable to chemical and biological samples.
• This work advances SERS applications in fields such as environmental monitoring and bioanalysis.