Self-Propelled Rolled-Up Polyelectrolyte Multilayer Microrockets

Engineering self-propelled micro-/nanomachines with ultrafast speeds and high towing forces is crucial for the efficient transportation of important objects in key biomedical and environmental applications. In this study, rolled-up nanomembrane technology is used for the first time for the controlled fabrication of layer-by-layer (LbL)-assembled microtubes and the corresponding chemical-powered microrockets. By integrating LbL assembly, microcontact printing, and a rolled-up nanomembrane technique, polyelectrolyte multilayer microplates of different shapes are transformed into well-defined microtubes. Coupled with platinum nanoparticles, the as-prepared microtubes can act as bubble-propelled microrockets with a very rapid speed and a large towing force. As a proof of concept, the rolled LbL microrockets confirm the feasibility of transporting single or multiple cells at high speed. Integrating the rolled-up nanomembrane technology and LbL assembly results in a simple, versatile, and low-cost approach and expands the scope of both polymer multilayer-based multifunctional tubes and artificial machines at the micro-/nanoscale.