Volume and porosity thermal regulation in lipid mesophases by coupling mobile ligands to soft membranes

TL;DR

This study explores how DNA linkers on lipid vesicles enable control over their shape and network porosity through temperature-dependent deformability and adhesion, revealing negative thermal expansion and tunable porosity.

Contribution

It introduces a model explaining the thermal regulation of liposome networks via DNA-mediated adhesion and deformability, highlighting novel collective properties.

Findings

Observation of negative thermal expansion in liposome networks

Demonstration of tunable porosity through temperature control

Development of a model linking deformability and DNA adhesion

Abstract

Short DNA linkers are increasingly being exploited for driving specific self-assembly of Brownian objects. DNA-functionalised colloids can assemble into ordered or amorphous materials with tailored morphology. Recently, the same approach has been applied to compliant units, including emulsion droplets and lipid vesicles. The liquid structure of these substrates introduces new degrees of freedom: the tethers can diffuse and rearrange, radically changing the physics of the interactions. Unlike droplets, vesicles are extremely deformable and DNA-mediated adhesion causes significant shape adjustments. We investigate experimentally the thermal response of pairs and networks of DNA-tethered liposomes and observe two intriguing and possibly useful collective properties: negative thermal expansion and tuneable porosity of the liposome networks. A model providing a thorough understanding of this unexpected phenomenon is developed, explaining the emergent properties out of the interplay between the temperature-dependent deformability of the vesicles and the DNA-mediated adhesive forces.