Magnetically-driven microscavengers for microplastic degradation in blood

Microplastics can traverse human physiological barriers, infiltrate and accumulate in critical organs and tissues (e.g., brain, blood, and heart) over extended periods, posing significant threats to human health. While microplastic degradation in aquatic environments (e.g., contaminated water) has been extensively studied, research on bloodstream microplastic degradation remains largely unexplored, leaving a critical gap in remediation strategies. To fill this gap, we pioneered the fabrication of biocompatible magnetically-driven Fe₃O₄@PDA-lipase microrobots by functionalizing Fe₃O₄ nanoparticles with polydopamine (PDA) and lipase for blood-borne microplastic degradation. In vitro blood experiments confirmed that this platform holds promise for future detoxification of circulating microplastics. The microrobots integrate synergistic functions: Fe₃O₄ enables magnetic responsiveness for precise movement control; PDA provides adhesive properties for robust microplastic binding; and lipase mediates enzymatic microplastic degradation. Guided by an external rotating magnetic field, the microrobots achieve targeted microplastic capture and in situ enzymatic degradation in blood without releasing harmful substances, addressing a pivotal safety concern for biomedical applications. Performance evaluations showed ~25% microplastic degradation efficiency in blood after 7 days of incubation. Additionally, the microrobots can be effectively recycled via magnetic separation post-degradation, reducing residuals and improving practicality. Hemolysis assays using rabbit blood and toxicity evaluations using human umbilical vein endothelial cells (HUVECs) and immunofluorescence experiments confirmed their excellent biocompatibility and immunogenicity, an indispensable prerequisite for potential in vivo translation. As a proof-of-concept study, this work provides a promising biocompatible approach for blood microplastic degradation and clearance, simultaneously overcoming the technical challenge of blood-specific targeted degradation and meeting safety requirements, thus laying a foundation for microrobot-based mitigation of microplastic health hazards.