(142g) Programmable Dynamic Self-Assembled DNA Nanostructures As Linear Actuators

Filaments can play key roles in inducing motion within biological cells and systems. For example, actin filaments can exert pushing force onto the plasma membrane through polymerization by their fast-growing end to induce membrane protrusion. Inspired by the actin polymerization, we developed a synthetic, programmable linear actuator using the dynamic growth and shrinkage of DNA nanotubes. This actuator consists of DNA nanotubes with attached capping structures that can be displaced by polymerization or depolymerization. New tiles are labeled by a different fluorophore and epifluorescence microscopy is performed to visualize the insertion displacement. We observed that when the free monomer concentration is higher than the critical value, new tiles are inserted at the nanotube-cap interfaces with flexible connections; no insertion occurs at the nanotube-seed interfaces with rigid interconnects. Reversely, depolymerization happens at the nanotube-cap interfaces with nanotubes getting shortened when the free monomer concentration is lower. Since the kinetics of nanotube tile self-assembly, which drives the displacement, are quite sensitive to monomer concentration, at a specific temperature we can tune the rates of nanotube polymerization and depolymerization by tuning the free monomer concentration. The DNA nanostructures we are building are programmable active elements whose motion could be sensitive to stimuli from the environment by coupling these stimuli to the modulation of monomer concentration. Insertion polymerization could also occur at multiple sites within DNA nanotube chains, so that larger structures could enable faster displacement.