DNA photofluids show life-like motion.

As active matter, cells exhibit non-equilibrium structures and behaviours such as reconfiguration, motility and division. These capabilities arise from the collective action of biomolecular machines continuously converting photoenergy or chemical energy into mechanical energy. Constructing similar dynamic processes in vitro presents opportunities for developing life-like intelligent soft materials. Here we report an active fluid formed from the liquid-liquid phase separation of photoresponsive DNA nanomachines. The photofluids can orchestrate and amplify nanoscale mechanical movements by orders of magnitude to produce macroscopic cell-like behaviours including elongation, division and rotation. We identify two dissipative processes in the DNA droplets, photoalignment and photofibrillation, which are crucial for harnessing stochastic molecular motions cooperatively. Our results demonstrate an active liquid molecular system that consumes photoenergy to create ordered out-of-equilibrium structures and behaviours. This system may help elucidate the physical principles underlying cooperative motion in active matter and pave the way for developing programmable interactive materials.