Melting transition in lipid vesicles functionalised by mobile DNA linkers

TL;DR

This study investigates the melting transition in lipid vesicles functionalized with mobile DNA linkers, combining simulations and experiments to understand how DNA-mediated interactions influence vesicle aggregation and membrane behavior.

Contribution

It introduces a combined modeling and experimental framework to analyze DNA-mediated vesicle interactions, highlighting the role of configurational costs and membrane deformability.

Findings

Vesicle aggregation is suppressed below a linker threshold.

Higher configurational costs hinder inter-vesicle bridge formation.

Membrane deformability influences DNA linker interactions.

Abstract

We study phase behaviours of lipid--bilayer vesicles functionalised by ligand--receptor complexes made of synthetic DNA by introducing a modelling framework and a dedicated experimental platform. In particular, we perform Monte Carlo simulations that combine a coarse grained description of the lipid bilayer with state of art analytical models for multivalent ligand--receptor interactions. Using density of state calculations, we derive the partition function in pairs of vesicles and compute the number of ligand--receptor bonds as a function of temperature. Numerical results are compared to microscopy and fluorimetry experiments on Large Unilamellar Vesicles decorated by DNA linkers carrying complementary overhangs. We find that vesicle aggregation is suppressed when the total number of linkers falls below a threshold value. Within the model proposed here, this is due to the higher configurational costs required to form inter--vesicle bridges as compared to intra-vesicle loops, which are in turn related to membrane deformability. Our findings and our numerical/experimental methodologies are applicable to the rational design of liposomes used as functional materials and drug delivery applications, as well as to study inter-membrane interactions in living systems, such as cell adhesion.