Isolation and Purification-Free Digital Single-Small Extracellular Vesicle Biosensing with Scalable Plasmonic Arrays

Nanosphere settling lithography enables arrayed gold nanodisks on invisible substrates with high refractive-index sensitivity and low spatial variability across 60 mm × 24 mm areas.

• Why it matters: Reproducible, scalable isolation and purification of small extracellular vesicles from biological fluids is hindered by specificity, efficiency, and time constraints, limiting quantitative liquid-biopsy measurements.
• What they did: The authors replaced nanosphere lithography with NSSL to fabricate AGNIS, then used PANORAMA for digital counting and sizing of 25, 50, and 100 nm polystyrene beads and for single-vesicle characterization of sEVs from H460 lung cancer cells.
• The result: Combined PANORAMA and fluorescence imaging quantifies miR-21 in sEVs from liver cancer patient plasma, identifying cancer-suspicious sub-populations while enabling sensitive single-sEV detection and simultaneous molecular profiling.

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