Three-dimensional plasmonic Au-Ag alloy nanostar/gold microflake hybrids for highly sensitive SERS detection

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Growing public concern necessitates high-sensitivity, rapid detection of food contaminants.
• Surface-enhanced Raman spectroscopy (SERS) is a promising technique for food analysis due to its sensitivity and speed.

Purpose of the Study:

• To develop and optimize a novel 3D substrate for enhanced SERS detection of hazardous food substances.
• To investigate the impact of plasmonic "hot spot" distribution on SERS enhancement.

Main Methods:

• Synthesis of gold microflakes (GMFs) and bimetallic Au-Ag alloy nanostars (Au-AgNSts).
• Construction of a 3D GMFs/Au-AgNSts substrate using liquid-liquid three-phase self-assembly.
• Systematic investigation of Au-to-Ag ratio and AgNO3 concentration for optimal SERS performance.

Main Results:

• Optimal SERS enhancement achieved with a 1:1 Au-to-Ag ratio and 250 μL of 2 mM AgNO3.
• Achieved low detection limits for Rhodamine 6G (10^-11 M) and crystal violet (10^-10 M).
• Demonstrated a low detection limit of 0.0313 g/L for aspartame with excellent substrate stability and uniformity.

Conclusions:

• The developed 3D GMFs/Au-AgNSts substrate exhibits high sensitivity, uniformity, and stability for SERS applications.
• This substrate shows significant potential for practical applications in food safety monitoring.
• Optimized plasmonic properties are crucial for achieving superior SERS enhancement.