Electrokinetic active grooves for liposome capture, confinement, trajectory analysis, and controlled release

Extracellular vesicles (EVs) are attractive candidates for minimally invasive disease monitoring. EV diagnostic signals often reside in low-abundant subpopulations, motivating single-vesicle measurements that can report distributions rather than ensemble averages. In practice, such assays rely on the transient migration of a mobile vesicle through a detection region or performing cycled processing/measurement steps on vesicles permanently immobilized on surfaces via affinity-based capture. Single-vesicle analysis would benefit from technologies that can combine characteristics of transient detection and surface immobilization to enable controlled capture, fixed time analysis and release of vesicles in a marker-neutral way. Here, we present reversible electrokinetic confinement (RECON) grooves, an electrokinetically active nanogroove platform that enables low-voltage, programmable capture, timed retention, and release of nanoscale vesicles within microscopic grooves under continuous optical access. The platform uses an embedded titanium electrode with thin TiO2 passivation, enabling stable actuation over multi-hour experiments. Using fluorescent, size-defined liposomes as controlled vesicle standards, we demonstrate (1) reversible, minute-long confinement at ≤5 V, (2) size-dependent confinement and escape behavior, and (3) optical quantification of groove-guided drift velocities. Together, these results establish RECON grooves as an electrically programmable platform for reversible vesicle handling, while providing quantitative, trajectory-derived measures of confinement and transport.