# Dynamic Shape Modulation of Deflated and Adhered Lipid Vesicles

## TL;DR

The paper explores how lipid vesicles can be deflated and flattened to mimic cell organelles, enabling studies on membrane shaping and protein sorting.

## Contribution

A new method to quantify adhesion strength and mechanical parameters of deflated vesicles using shape analysis and geometric relationships.

## Key findings

- Deflated vesicles can reach reduced volumes as low as 0.1, similar to Golgi cisternae and ER sheets.
- Adhesion strength can be estimated from vesicle aspect ratio, size, and bending rigidity.
- The Canham-Helfrich model helps determine mechanical parameters like membrane tension and pressure.

## Abstract

Lipid membrane-bounded organelles often possess intricate
morphologies
with spatially varying curvatures and large membrane surface areas
relative to internal volume (small reduced volumes). These features
are thought to be essential for protein sorting and vesicle trafficking,
but challenging to reproduce in vitro. Here, we show
that weakly adhered giant unilamellar vesicles (GUVs) can be osmotically
deflated to reduced volumes as low as 0.1, similar to what is found
in flattened, disc-shaped organelles such as Golgi cisternae and ER
sheets. Using shape analysis with the Canham-Helfrich model, we determine
mechanical parameters including adhesion strength, membrane tension,
and pressure of individual vesicles. We find that the rate of shape
flattening during deflation is governed by a normalized adhesion strength
that combines vesicle size, adhesion energy, and bending rigidity.
For highly flattened disc-like vesicles, we identify a geometric relationship
that allows the adhesion strength to be estimated solely from the
vesicle’s aspect ratio, size, and bending rigidity. These results
provide a quantitative experimental platform for bottom-up studies
of membrane shaping mechanisms and shape-dependent phenomena, such
as curvature-mediated protein sorting.