(397d) Organized Self-Assembly of Janus Catalytic Nanomotors

Locomotion of synthetic nano-/microscale objects through fluid environments is one of the most exciting and challenging areas of nanotechnology. Inspired by animal interactions, the ability of synthetic nanoscale motors to produce self-organized structures is of considerable interest, owing to their future implications in nanomedicine, nanomachinery, transport systems, and chemical sensing. Organized self-assemblies of Janus catalytic motors, induced by hydrophobic surface interactions involving multiple motor/motor and motor/nonmotor particles, display controlled coordinated self-propulsion. These assemblies were prepared by octadecyltrichlorosilane (OTS) modification of the surface of a silica microparticle and addition of a catalytic Pt hemispheric coating. The influence of the self-assembled structures upon the motion behavior is investigated. Different bonding orientations between these hydrophobic Janus motors induce different forms of motion. The relative orientation of each motor in the assembly changes its contribution to the net propulsion force and rotational moment. The hydrophobic interactions between individual micromotors and micromotor assemblies can promote a continuous growth of the assembly during its movement and lead to dynamic changes in the motion behavior. Organized assemblies of multiple motor/nonmotor particles are also illustrated toward optimal cargo transport and delivery. Such controlled structures and motion of chemically powered Janus nanomotor assemblies hold considerable promise for the creation of intelligent nanomachines that perform collective tasks.