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arXiv · 2301.06134

Competition between self-assembly and phase separation governs high-temperature condensation of a DNA liquid

Omkar Hegde·Tianhao Li·Anjali Sharma·Marco Borja·William M. Jacobs·W. Benjamin Rogers
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Abstract

In many biopolymer solutions, attractive interactions that stabilize finite-sized clusters at low concentrations also promote phase separation at high concentrations. Here we study a model biopolymer system that exhibits the opposite behavior: Self-assembly of DNA oligonucleotides into finite-sized, stoichiometric clusters, known as "DNA nanostars", tends to inhibit phase separation of the oligonucleotides at high temperatures. We use microfluidics-based experiments to map the phase behavior of DNA nanostars at high concentrations of divalent cations, revealing a novel phase transition in which the oligonucleotides condense upon increasing temperature. We then show that a theoretical model of competition between self-assembly and phase separation quantitatively predicts changes in experimental phase diagrams arising from DNA sequence perturbations. Our results point to a general mechanism by which self-assembly shapes phase boundaries in complex biopolymer solutions.

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Omkar Hegde, Tianhao Li, Anjali Sharma, Marco Borja, William M. Jacobs, W. Benjamin Rogers. 2023-01-15. Competition between self-assembly and phase separation governs high-temperature condensation of a DNA liquid. https://doi.org/10.1103/physrevlett.132.208401

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