Liquid-state quantitative SERS analyzer on self-ordered metal liquid-like plasmonic arrays.

Area of Science:

• Plasmonics
• Nanotechnology
• Spectroscopy

Background:

• Liquid interfacial plasmonic platforms are emerging for sensors, catalysis, and tunable optical devices.
• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity but often relies on solid substrates or nanoparticle sols, limiting practicality.
• Developing a stable, quantitative liquid-state SERS platform is a significant challenge.

Purpose of the Study:

• To develop a practical and quantitative liquid-state SERS platform.
• To demonstrate the self-assembly of 3D plasmonic arrays at liquid interfaces.
• To create a stable, reproducible SERS system using gold nanorods.

Main Methods:

• Vigorous mixing of chloroform with citrate-capped gold nanorod sols.
• Formation of 3D plasmonic arrays at the chloroform/water (O/W) interface.
• Utilizing reversible O/W encasing in a cuvette based on surface wettability.
• Employing a portable Raman device for SERS analysis.

Main Results:

• Rapid self-assembly of 3D plasmonic arrays at the O/W interface, forming a self-healing, liquid-like golden droplet.
• The O phase generated stable SERS fingerprints, serving as a homogeneous internal standard for quantitative analysis.
• Both oil-in-water (O/W) and water-in-oil (W/O) platforms exhibited excellent SERS sensitivity and reproducibility for various analytes.

Conclusions:

• The developed liquid interfacial plasmonic platform offers a promising alternative for practical SERS applications.
• This system paves the way for a quantitative liquid-state SERS analyzer comparable to UV-Vis spectrometers.
• The self-healing, reproducible nature of the platform surpasses limitations of traditional solid-state or sol-based SERS methods.