From Shallow to Full Wrapping: Geometry and Deformability Dictate Lipid Vesicle Internalization

Area of Science:

• Biophysics
• Cell Biology
• Materials Science

Background:

• Vesicle deformability and adhesion are crucial for membrane processes like endocytosis and viral entry.
• Understanding these mechanics is key to advancing drug delivery and intercellular transport.

Purpose of the Study:

• To establish a mechanical criterion for vesicle engulfment by lipid membranes.
• To develop a tunable experimental system for studying vesicle-membrane interactions and engulfment dynamics.

Main Methods:

• Utilized giant unilamellar vesicles (GUVs) interacting via depletion-induced adhesion.
• Combined experimental approaches with continuum simulations and 3D confocal reconstructions.
• Quantified the bendocapillary length to understand membrane bending versus adhesion competition.

Main Results:

• Constructed a state diagram for endo- and exocytic engulfment of small GUVs by larger ones.
• Demonstrated that vesicle size relative to bendocapillary length dictates engulfment geometry.
• Showcased light-induced switching between wrapping states using photoresponsive lipids.

Conclusions:

• Established a mechanical criterion governing vesicle engulfment, dependent on deformability and adhesion.
• Developed a versatile platform for studying soft cargo uptake and membrane dynamics.
• The findings provide insights into fundamental biological processes and potential therapeutic applications.