Specificity, flexibility and valence of DNA bonds guide emulsion architecture

TL;DR

This paper demonstrates how DNA grafting on emulsion droplets enables controlled self-assembly into flexible or rigid structures by tuning valence and bond specificity, advancing programmable material design.

Contribution

It introduces a method to control emulsion architecture via DNA-mediated valence and flexibility, supported by a thermodynamic model for patch size prediction.

Findings

Valence 2 yields flexible droplet polymers.

Valence above 4 results in rigid droplet networks.

Patch size increases with droplet size, DNA concentration, and tether stiffness.

Abstract

The specificity and thermal reversibility of DNA interactions have enabled the self-assembly of crystal structures, self-replicating materials and colloidal molecules. Grafting DNA onto liquid interfaces of emulsions leads to exciting new architectural possibilities due to the mobility of the DNA ligands and the patches they form between bound droplets. Here we show that the size and number of these adhesion patches (valency) can be controlled. Valence 2 leads to flexible polymers of emulsion droplets, while valence above 4 leads to rigid droplet networks. A simple thermodynamic model quantitatively describes the increase in the patch size with droplet radii, DNA concentration and the stiffness of the tether to the sticky-end. The patches are formed between droplets with complementary DNA strands or alternatively with complementary colloidal nanoparticles to mediate DNA binding between droplets. This emulsion system opens the route to directed self-assembly of more complex structures through distinct DNA bonds with varying strengths and controlled valence and flexibility.