A Wettability Contrast SERS Droplet Assay for Multiplexed Analyte Detection

Area of Science:

• Plasmonics and Nanotechnology
• Analytical Chemistry
• Biosensing

Background:

• Droplet assay platforms offer advantages like sample compartmentalization and high throughput.
• Multiplexed detection in droplet assays faces challenges, limiting their widespread application.
• Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for sensitive analyte detection.

Purpose of the Study:

• To develop a novel plasmonic droplet assay platform (PDAP) for multiplexed analyte detection.
• To enable sensitive detection using SERS on a microfluidic platform.
• To demonstrate the platform's utility for detecting food adulterants.

Main Methods:

• Fabrication of a PDAP using wettability contrast to split microliter droplets into nanoliter volumes.
• Functionalization of gold nanoparticles (AuNPs) with (3-aminopropyl) triethoxysilane (APTES) for controlled adhesion.
• Utilizing gravity-driven flow and a scotch-tape mask for creating distinct hydrophilic and hydrophobic zones.

Main Results:

• The PDAP successfully split aqueous droplets with varying surface tensions into ultralow volumes.
• Multiplexed detection of Rhodamine 6G (Rh6G) and Crystal Violet (CV) achieved limits of detection of 134 pM and 10.1 nM, respectively.
• Demonstrated high sensitivity in detecting food adulterants in spiked milk samples.

Conclusions:

• The developed PDAP offers a sensitive and efficient method for multiplexed SERS-based detection.
• The platform exhibits comparable sensitivity to existing methods and potential for practical applications.
• PDAP shows significant promise for the multiplexed screening of food adulterants.