Controlled molecular assembly toward self-propelled micro-/nanomotors

Micro-/nanomotors (MNMs) are able to propel themselves in fluids through converting different energies from environment into kinetic energy. Recently, layer-by-layer (LbL) assembly, a versatile assembly approach, has been employed to access MNMs with advantages such as regulated motion, stimuli-response properties, and multifunctionality. In this chapter, we review the recent progress on controlled fabrication, motion control, and biomedical applications of MNMs based on controlled molecular assembly. Through integrating diverse functional building blocks such as nanoparticles, enzymes, and metal shells, MNMs with various structures (e.g., hollow capsules and nanotubes) have been prepared, and the control over the on/off state of the MNM motion has been realized. In addition, we also discuss a special type of MNMs which is derived from the combination of as-assembled biological aggregates and artificial nanostructures. These MNMs can be driven by bubble recoil, irradiation by near-infrared light, and ultrasonic fields. We have also demonstrated the potential applications of these assembled MNMs in biomedical fields such as targeted drug delivery, photothermal therapy, and detoxification.