Motion control of urea powered biocompatible hollow microcapsules

Abstract

The quest for biocompatible micro-swimmers powered by compatible fuel and with full motion control over their self-propulsion is a long-standing challenge in the field of active matter and microrobotics. Here, we present an active hybrid microcapsule motor based on Janus hollow mesoporous silica micro particles (JHP) powered by the bio-catalytic decomposition of urea at physiological concentrations. The directional self-propelled motion lasts longer than 10 minutes with an average velocity of up to 5 body lengths per second. Additionally, we control the velocity of the micro-motor by chemically inhibiting and reactivating the enzymatic activity of urease. The incorporation of magnetic material within the Janus structure provides remote magnetic control on the movement direction. Furthermore, the mesoporous/hollow structure can load both small molecules and larger particles up to hundreds of nano-meters, making the hybrid micro-motor an active and controllable drug delivery micro-system.