Growing functional artificial cytoskeletons in the viscoelastic confinement of DNA synthetic cells

Intracellular structures, such as cytoskeletons, form within a crowded cytoplasm with viscoelastic properties. While self-assembly in crowding is well studied, the effects of coupled viscoelastic environments remain elusive. Here we engineer all-DNA synthetic cells (SCs) with tunable viscoelastic interiors to investigate this phenomenon. We introduce facile DNA barcode engineering to selectively enrich DNA tiles with adjustable concentrations into SCs to form artificial cytoskeletons coupled to their interior. Distinct mechanistic differences in assembly occur compared with solution or simple crowding. Furthermore, we develop light, molecular and metabolic switches to direct structure formation and create self-sorted SC populations with distinct artificial cytoskeletons. These cytoskeletons strengthen SCs and support stable contacts with mammalian cells. By bridging molecular-scale DNA nanotube assembly with mesoscale condensate structures, our SCs provide a versatile platform to investigate self-assembly under viscoelastic confinement and to harness subcellular architectures for emerging applications.