Self-propelled Janus magnetic micromotors as peroxidase-like nanozyme for colorimetric detection and removal of hydroquinone†

Micromotors, which combine nanotechnology with autonomous movement, have attracted extensive interest in the field of environmental monitoring and remediation. However, it is still a challenge to develop a facile method to prepare a multifunctional micromotor for simultaneously detecting and removing organic pollutants from water. Herein, we report a novel magnetically controllable Janus micromotor with peroxidase-like activity for simultaneous colorimetric detection and degradation of hydroquinone (HQ). Such polyethylene glycol (PEG) modified Janus micromotor was composed of calcined manganese(II) acetate modified Fe₃O₄@polyacrylic acid (PAA) and ferric oxide (Fe₃O₄) nanoparticles. The obtained Janus micromotors (P-FM JMMs) have a unique asymmetric structure and exhibit autonomous motion with a maximum speed of 95.2 ± 3.02 μm s^?1 in the presence of 100 mM H₂O₂. Combining the advantages of autonomous motion and superior peroxidase-like activity, P-FM JMMs as effective micromotors were established for dynamic sensitive colorimetric detection of HQ with a detection limit of 0.0923 μM and rapid degradation of HQ via excellent Fenton-like activity in water. In addition, such Janus micromotors also could achieve effective magnetic recovery to reduce water pollution. The strategy provides a new insight for the future multifunctional task allocation of micromotors on demand.