Light-driven biohybrid microrobots for contact-enhanced photoenzymatic degradation of plastic debris

Abstract Light-driven self-propelled microrobots offer opportunities for active environmental remediation by enabling controllable interactions with dispersed pollutants in aqueous environments. Here, we report biohybrid microrobots, composed of enzyme-functionalized, Au-decorated cubic hematite, that reversibly switch between clustered and dispersed states to enhance microrobot-substrate interactions and photoenzymatic degradation. In the dark, microrobots spontaneously assemble into interconnected filamentous clusters. Under blue-light irradiation, these clusters disassemble into self-propelled microrobots, increasing catalyst exposure and promoting broader microrobot-substrate interactions. Applied to polylactic acid (PLA) plastics, this collective-to-individual transition increases repeated microrobot-substrate contacts and promotes ester-bond hydrolysis at the polymer-water interface. Mass spectrometry identifies soluble PLA-derived oligomers, while electron microscopy reveals localized surface erosion after photoenzymatic treatment. By dynamically redistributing enzyme-functionalized microrobots across the polymer surface, reversible light-controlled switching enhances transient catalytic interactions and surface exploration. This strategy provides a general approach for optimizing photoenzymatic degradation by coupling collective organization, active motion, and catalyst accessibility in aqueous environments, while preserving reversible control over their spatial organization and activity.