Surface plasmon coupled emission in micrometer-scale cells: a leap from interface to bulk targets

Area of Science:

• Biophysics
• Spectroscopy
• Cell Biology

Background:

• Surface plasmon coupled emission (SPCE) is a sensitive technique for biomolecular analysis and cell imaging, typically limited to nanoscale interfaces.
• Complex coupling modes are expected for micrometer-scale samples, necessitating exploration of new SPCE properties.

Purpose of the Study:

• To investigate the application of SPCE spectroscopy for analyzing micrometer-scale biological samples, specifically cells.
• To explore the potential of SPCE for 3D cell imaging and real-time monitoring of cellular processes.

Main Methods:

• Utilized an SPCE spectroscopy system to study cells with labeled subregions (membrane, cytoplasm, nucleus).
• Investigated the impact of metallic substrates (Au, Ni, Al) on SPCE properties.
• Monitored SPCE intensity for real-time detection of cell labeling.

Main Results:

• Observed angular and p-polarized emission from different cellular subregions.
• SPCE signals remained partially p-polarized with consistent maximum emission angles across varying wavelengths, fluorophore distributions, and stained layer thicknesses.
• Increased sample thickness led to enhanced polarization and broader angle distribution.
• Aluminum substrates showed superior polarization and angle distribution compared to gold and nickel.

Conclusions:

• SPCE can be extended from surface analysis to 3D imaging of bulk targets, moving beyond nanoscale interfaces.
• The findings provide a foundation for applying SPCE to study cell membrane fluidity, intracellular biomolecule interactions, and cell subregion differentiation.
• Real-time detection of cellular labeling processes was successfully achieved using SPCE intensity monitoring.