Magnetic and photoactive colloidal shuttles for active cargo transportation

Abstract

Colloidal shuttles are micro/nanoscale motors that display controllable cargo loading/release and programmable navigation, which are emerging delivery vehicles at the small scale. Here we present a hydrogen peroxide-fueled catalytic colloidal shuttle composed of a hematite cube half coated with platinum, i.e. a Pt/hematite Janus cube, which can be remotely controlled with ease by light and magnetic field. Interestingly, the dynamic behaviors of the Pt/hematite motor under light illumination in lower fuel concentration are similar to those Pt-based motors in higher fuel concentration without UV light, including the self-propulsion direction and the interaction with passive particles. In lower fuel concentration, we demonstrate the ability of the Pt/hematite motor for light-switchable cargo loading and release, and programmable and directional transportation of cargoes using the intrinsic magnetic property of hematite. Our work offers an efficient colloidal shuttle that operates at favorable fuel concentration and light intensity in comparison to earlier reported cargo-towing colloidal motors, which should find applications as microscale delivery vehicles, particularly for cargo transportation on microchips.