Synergistic magneto-enzymatic propulsion enables multimodal nanomotor swarms

Abstract

Enzymatic nanomotors self-propel by converting free molecular energy from chemical reactions. While initially used mainly as individual particles, these systems are increasingly implemented as swarms, where collective effects enable adaptable navigation in complex environments, broader coverage and enhanced local agent concentration. However, most studies have focused on planar swarming, and collective systems that combine magnetic navigation with enzyme-powered motion remain largely underexplored. Here, as a mechanistic proof-of-principle, we introduce urease-powered nanomotors based on bioproduced magnetosomes that operate in two sequential collective modes: (i) magnetic localization of the ensemble and (ii) catalysis-triggered, interface-dependent expansion of that localized cloud. We investigate this catalytic collective phenomenon under varying conditions, including particle and substrate concentrations, media viscosity, and confinement, and devote particular attention to distinguishing urea-driven buoyant accumulation from catalysis-dependent interfacial spreading using combined top/side-view imaging and inactive particle controls. Finally, we examine the swarm under a magnetic field gradient to concentrate it in a target area and then trigger catalytic expansion. In confined environments, where the free-interface expansion is suppressed, magnetic localization and local enrichment remain operative. Rather than targeting a specific immediate application, this work establishes a two step collective strategy, clarifies the mechanism underlying a distinct catalytic swarm mode, and defines the physical conditions that may support future environmental and biomedical implementations of multimodal nanomotor swarms. Enzyme-powered nanomotors are primarily studied as individual particles with limited understanding of their collective behaviors, especially in three-dimensional and interface-dependent environments. This study reports a mechanistic proof-of-principle for a two-step multimodal nanomotor swarm that combines magnetic localization with catalysis-triggered interfacial expansion, elucidating the physical conditions governing their collective dynamics.