Streamlined Digital Microfluidics-Mass Spectrometry Strategy for Extracellular Vesicle Enrichment and Lipid Profiling

Extracellular vesicles (EVs) are nanoscale mediators of intercellular communication that contribute to disease processes, such as tumor progression and immune regulation. However, EV lipidomics remains constrained by conventional isolation methods that require large sample volumes, long processing times, and limited compatibility with downstream lipid characterization, impeding studies of scarce specimens (e.g., macrophage-derived EVs from specific physiological states). Here, we report a multiplexed digital microfluidic (DMF) platform integrated with mass spectrometry for rapid EV isolation and on-chip lipidomic profiling from trace samples. EVs are captured using ZrO₂-coated magnetic beads (ZrO₂@Fe₃O₄), where Zr⁴⁺ Lewis acidic sites coordinate with phosphate groups on the EV membrane to enable efficient binding. Following capture, lipids are extracted directly on-chip and analyzed by MS. The workflow isolates EVs from microliter-scale biological samples within 15 min, preserves EV activity, and achieves a recovery of 78%. While this recovery is comparable to ultracentrifugation (84%), the DMF approach reduces processing time from >2 h to 15 min. Lipid profiling of HeLa-cell-derived EVs revealed broad lipid coverage. When applied to macrophage EVs, the platform resolved subtype-dependent lipid remodeling between resting M0 and anti-inflammatory M2 states: M2 EVs showed increased anti-inflammatory fatty acids (palmitoleic acid and docosahexaenoic acid) and decreased cholesterol esters. This integrated DMF-MS strategy enables fast, low-volume EV enrichment and lipidomic interrogation, supporting studies of rare samples and accelerating translational applications in immunometabolism and diagnostics.