Sustained growth of nanotubes by self-assembly of DNA strands at room temperature

Artificial biomolecular nanotubes are a promising approach to build materials mimicking the capacity of the cellular cytoskeleton to grow and self-organize dynamically. Nucleic acid nanotechnology has demonstrated a variety of self-assembling nanotubes with programmable, robust features, and morphological similarities to actual cytoskeleton components. However their production typically requires thermal annealing that is not only incompatible with physiological conditions but also hinders the possibility for continuous growth and dynamic self-organization. Here we report DNA nanotubes that self-assemble from a simple mixture of five short DNA strands at constant room temperature, with remarkable capability to sustainably grow over prolonged time. The assembly, done in a monovalent salt buffer (here, 100 mM NaCl), ensures that the nanoscale features of the nanotubes are preserved under these isothermal conditions, enabling continuous growth up to 20 days and the formation of individual nanotubes with near flawless arrangement, a diameter of 22 ± 4 nm, and length of several tens of micrometers. We demonstrate the crucial role of the monovalent cation to achieve such properties. We finally encapsulate the strands in micro-sized compartments, such as water-in-oil microdroplets and giant unilamellar vesicles serving as simple cell models. Notably, nanotubes not only isothermally grow in these conditions, but also self-organize into dynamic higher-order structures, such as rings and dynamic networks, demonstrating that cytoskeleton-like properties can emerge from a combination of sustained growth and confinement. Our study suggests a method for engineering biomolecular scaffolds and materials that display sustained dynamic and life-like properties.