Abstract
In many biomolecular solutions, multivalent interactions that promote
complexation lead to phase separation at high concentrations. Here we study a
model biomolecular system that exhibits the opposite behavior: Self-assembly
into multisubunit complexes inhibits phase separation, even though the same
intermolecular interactions underlie both processes. We use microfluidics-based
experiments to show that DNA nanostars, which are known to phase separate at
low temperatures, can also phase separate upon disassembly at high temperatures
and high concentrations of divalent cations. We introduce a theoretical model
that quantitatively reproduces this novel re-entrant phase behavior, providing
a unified view of the competition between self-assembly and phase separation in
biomolecular solutions.