writer：Yingjie Wu,Zhiguang Wu,Xiankun Lin,Qiang He*,and Junbai Li
keywords：layer-by-layer assembly, Janus capsule, autonomous motor, smart cargo
source：期刊
Issue time：2012年

We demostrate the first example of a self-propelled Janus polyelectrolyte multilayer hollow capsule that can serve as both autonomous motor and smart cargo. This new autonomous Janus capsule motor composing of partially coated dendritic platinum nanoparticles (Pt NPs) was fabricated by using a template-assisted layer-by-layer (LbL) self assembly combined with micro-contact printing method. The resulting Janus capsule motors still retain outstanding delivery capacities and can respond to external stimuli for controllable encapsulation and triggered release of model drugs. The Pt NPs on the one side of Janus capsule motors catalytically decompose of hydrogen peroxide fuel, generating oxygen bubbles and then recoiling the movement of capsule motors in solution or at interface. They could autonomously move at a maximum speed of above 1 mm/s (over 125 body lengths/s), while exerting large forces exceeding 75 pN. Also, these asymmetric hollow capsules can be controlled by external magnetic field to achieve directed movement. This LbL-assembled Janus capsule motor system is potential in making smart self-propelling delivery systems.