Three-Dimensional Plasmonic Trap Array for Ultrasensitive Surface-Enhanced Raman Scattering Analysis of Single Cells

Area of Science:

• Biotechnology
• Analytical Chemistry
• Spectroscopy

Background:

• Single-cell analysis is crucial for understanding cellular heterogeneity.
• Surface-enhanced Raman scattering (SERS) shows promise for label-free single-cell analysis but faces challenges in extracellular metabolite characterization.

Purpose of the Study:

• To develop a convenient and sensitive method for simultaneous compartmentalization and detection of single-cell extracellular metabolites.
• To create a 3D plasmonic trap array for enhanced SERS measurements at the single-cell level.

Main Methods:

• Fabrication of 3D plasmonic traps via an interfacial-energy-driven process using polydimethylsiloxane (PDMS) and silver nitrate (AgNO3).
• In-situ formation and self-assembly of silver nanoparticles within the 3D traps to create flower-like microstructures for plasmon enhancement.
• Utilizing the 3D traps for sensitive SERS detection of analytes, including p-aminothiophenol and dipicolinic acid from single bacterial spores.

Main Results:

• The 3D plasmonic traps exhibited significantly enhanced surface plasmon resonance signals.
• A low detection limit at the zeptomolar (aM) level was achieved for p-aminothiophenol.
• Successful label-free detection of dipicolinic acid, a bacterial spore biomarker, from a single cell was demonstrated.

Conclusions:

• The developed 3D plasmonic trap array is a versatile and efficient tool for sensitive, label-free SERS analysis of single-cell extracellular metabolites.
• This approach advances the capability of SERS for detailed characterization of single-cell environments.
• The technology holds potential for various applications in cell biology and diagnostics.