arXiv subjects

Laura R. Arriaga

Publications and source records attributed to Laura R. Arriaga.

4 recordsLinked to original sources

arXiv2025

Mechanical performance of hybrid polymer-lipid vesicles with leaflet asymmetry engineered using microfluidics

Lipid vesicles consist of aqueous cores surrounded by a bilayer of phospholipids. Hybrid polymer-lipid vesicles incorporate both polymers and lipids, offering promising properties for developing pharmaceuticals, biosensors, and artificial cells. The hybrid vesicles can be symmetric, in which their two leaflets contain identical compositions, or asymmetric, in which the leaflets possess dissimilar compositions and can lead to dramatically modified properties. However, methods to produce both symmetric and asymmetric hybrid vesicles result in heterogenous compositions and sizes, making it challenging to quantify the effect of asymmetry and limiting applications. Here, we use a microfluidic approach to produce hybrid vesicles containing symmetric or asymmetric leaflets with precisely engineered compositions. We find the vesicles with asymmetric leaflets are significantly stiffer and tougher than those with symmetric leaflets; moreover, the lateral diffusivity of lipids is greatly decreased. The structure for improved toughness consists of an inner leaflet that is a stretchable lipid leaflet and an outer leaflet that is a fully continuous polymer leaflet. This technique of precisely engineering asymmetric structures may be applied to hybrid vesicles composed of block copolymers and phospholipids dissolvable in chloroform and hexane, further expanding their applications.

cond-mat.soft↗

arXiv2025

Membrane-mediated force transduction: Stick-slip motion of vesicles with fluid membranes

How internal forces are transduced into motion through soft, fluid membranes remains a fundamental question in the study of active systems. To investigate this coupling, we develop a minimal system consisting of a single ferromagnetic particle encapsulated within a lipid vesicle with controlled membrane composition and phase behavior. An external rotating magnetic field actuates the particle, which rotates and translates along the inner membrane leaflet. This motion generates local slip in the membrane; near a substrate, the slip creates a shear gradient across the lubrication gap that propels the vesicle forward. Propulsion is intermittent and strongest when the particle moves near the vesicle bottom, where stress transmission is most effective. We find that the coupling between internal flows and vesicle motion is highly sensitive to membrane elasticity, excess area, and phase coexistence. Local membrane deformation and flow dissipate part of the stress, limiting the efficiency of force transduction. Additionally, membrane fluctuations and external boundaries reduce particle mobility, and in phase-separated membranes, line tension at domain boundaries deflects the particle and gradually reorients membrane structure. These results demonstrate that lipid membranes not only transmit internal stresses but also remodel themselves in response, actively shaping the dynamics of force transduction and motion in active systems.

cond-mat.soft↗

arXiv2025

Rolling, sliding and trapping of driven particles in square obstacle lattices

Transport phenomena in complex and dynamic microscopic environments are fundamentally shaped by hydrodynamic interactions. In particular, microparticle transport in porous media is governed by the delicate interplay between particle-substrate friction and pressure forces. Here, we systematically investigate the motion of externally driven rotating magnetic microparticles near a substrate patterned with a square lattice of cylindrical obstacles, a model porous medium. Remarkably, we observe a reversal in the direction of particle translation as obstacle spacing decreases, highlighting a sensitive competition between shear-induced forward rolling and pressure-driven backward sliding due to flow-field symmetry breaking. These results demonstrate the crucial role of structured environments in determining microscale active particle transport, offering novel strategies for microfluidic design, targeted cargo delivery, and tunable active materials.

cond-mat.soft↗

arXiv2024

Rolling vesicles: From confined rotational flows to surface-enabled motion

The interaction of surfaces in relative motion in wet environments is dominated by lubrication forces, which play a pivotal role in the dynamics of microscopic systems. Here, we develop motile vesicles that exploit lubrication forces to roll on substrates. The activity of the vesicle comes from the confined rotational flow generated by a driven rotating particle encapsulated within the vesicle by droplet-microfluidics. Lubrication forces driving vesicle rolling are controlled by membrane mechanics and its tribological properties. This provides the design principles for motile vesicles that exploit frictional forces to efficiently navigate through complex environments.

cond-mat.soft↗