Entry of Microparticles into Giant Lipid Vesicles by Optical Tweezers

TL;DR

This study demonstrates that microparticles can enter giant lipid vesicles when external picoNewton forces are applied, highlighting the roles of membrane tension and particle size in membrane crossing.

Contribution

It reveals the conditions under which microparticles penetrate lipid membranes without strong binding interactions, emphasizing the importance of external forces and membrane properties.

Findings

Particles can penetrate vesicles with picoNewton forces.

A force minimum exists when particle size matches the bendocapillary length.

Membrane tension influences particle entry feasibility.

Abstract

Entry of micro- or nano-sized objects into cells or vesicles made of lipid membranes occur in many processes such as entry of viruses in host cells, microplastics pollution, drug delivery or biomedical imaging. Here, we investigated the microparticle crossing of lipid membranes in giant unilamellar vesicles in the absence of strong binding interactions (e.g. streptavidin-biotin binding). In these conditions, we observed that organic and inorganic particles can always penetrate inside the vesicles provided that an external picoNewton force is applied and for relatively low membrane tensions. In the limit of a vanishing adhesion, we pointed out the role of the membrane area reservoir and show that a force minimum exists when the particle size is comparable to the bendocapillary length.