Pessoa, M. A. S. | bioRxiv Science

bioRxiv2026

Non-equilibrium cyclic conformations of DNA under electrokinetic confinement

Classic nanofluidic devices harness geometric confinement to modulate single polymer conformation and control chain dynamics. While classic nanofluidic devices have given rise to a range of applications, they are fundamentally limited by the static nature of their construction, which restricts real time control over molecular conformations. The reversible electrokinetic confinement (RECON) technique enables time-dependent control of DNA conformations in nanowells via dynamic modulation of field-induced confinement. Here, we demonstrate that applying dynamically varying confinement using stochastic and periodic signals can drive the confined polymer to access a range of non-equilibrium states, with the distinct configurations quantified via their radius of gyration tensor. For periodic driving, the device allows controlled cycling across conformational states, with distinct hysteresis observed in the shape anisotropy modulation. We quantify the interplay between the driving frequency, driving amplitude, and resulting hysteresis. Overall, our results establish RECON as a platform for active manipulation of single molecules, opening new avenues for studying non-equilibrium polymer physics and developing high-throughput, dynamically tunable nanofluidic devices.

biophysics↗

bioRxiv2026

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 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 electrokinetically active (RECON) grooves that provides low-voltage, programmable capture, timed retention, and release of nanoscale vesicles within microscopic grooves under continuous optical access. The platform uses a titanium embedded electrode with thin TiO2 passivation, enabling stable actuation over multi-hour experiments. Using fluorescent, size-defined liposomes as standards, we demonstrate (1) reversible, minute-long confinement at <5 V, (2) size-dependent confinement times, and (3) optical quantification of groove-guided drift velocities. Together, these results establish RECON grooves as a reusable, electrically programmable platform for controlled capture, timed retention, and release, while providing quantitative, trajectory-derived measures of confinement and transport.

biophysics↗