Acoustofluidic Chromatography for Extracellular Vesicle Enrichment from µL Blood Plasma Samples

We present a novel acoustofluidic chromatography platform for high-throughput nanoparticle trapping and enrichment, focusing on extracellular vesicles (EVs) from blood plasma. The system consists of a packed bed of polystyrene beads within a rectangular glass capillary, acoustically excited by a piezoelectric element. Using fluorescent polystyrene particles (1.9 µm and 0.27 µm) as model nanoparticles, we characterized the device by evaluating its trapping efficiency across a frequency range of 0.45–4 MHz. Our results demonstrate efficient trapping of micro- and nanoscale particles, with increased efficiency at higher acoustic powers and lower flow rates. EV isolation from 4 µL of diluted blood plasma showed that abruptly increasing the flow rate during the release step significantly enhanced particle recovery, likely due to hydrodynamic effects. Nanoparticle tracking analysis confirmed the release of EVs at concentrations of ~2x10⁹ particles/mL, with low protein background suitable for downstream mass spectrometry. This platform offers a promising approach for nanoparticle trapping and EV enrichment with minimal sample volumes, presenting potential applications in diagnostics and therapeutic development. Future work will focus on optimizing bead materials and sizes for EV subpopulation separation and scaling the system for clinical use.