Acoustofluidic Chromatography for Extracellular Vesicle Enrichment from 4 μL Blood Plasma Samples

We present a novel acoustofluidic chromatography platform for high-throughput nanoparticle trapping and enrichment, with a focus on extracellular vesicles (EVs) from blood plasma. The system features a packed bed of polystyrene beads inside a rectangular glass capillary, acoustically actuated by a piezoelectric element. Using fluorescent polystyrene nanoparticles as small as 25 nm, we characterized device performance across a frequency range of 0.45-4 MHz, demonstrating particle trapping at all tested frequencies. The platform achieved recoveries of up to 42.9 ± 3.2% at input powers as low as 55 mW and operated at high flow rates of up to 200 μL/min. Trapping capacity reached 6.7 × 10⁹ ± 2.5 × 10⁹ particles for 25 nm polystyrene beads. For EV isolation, processing just 4 μL of blood plasma yielded 2 × 10⁸ washed EV-sized particles eluted in 100 μL within 8 min. Micro BCA analysis confirmed a plasma protein background below 2 μg/mL, enabling downstream mass spectrometry. This platform provides an efficient, high-throughput approach for nanoparticle trapping and EV enrichment with minimal sample volumes, offering potential applications in diagnostics and therapeutic development. Future work will focus on optimizing bead properties for EV subpopulation separation and scaling the system for clinical applications.