Magnetically actuated microrobotic system for sequential treatment of biofilm

Clinical Snapshot

Key Findings

• P Value: Not reported in abstract

• Effect Size: Not quantified in abstract — described qualitatively as 'effective' and 'significant'

• Primary Outcome: Effective biofilm removal in rat periprosthetic joint infection model with MZ-8 microrobotic system

• Nnt Or Sensitivity: Not applicable at this preclinical stage; no NNT, sensitivity, specificity, or hazard ratio data available

• Confidence Interval: Not reported

Clinical Application

Clinical feasibility is unestablished. Significant engineering, regulatory, and clinical translation barriers remain: device miniaturisation for human joint deployment, real-time NIR-II imaging integration into operating theatre workflows, operator training for magnetic navigation, sterilisation protocols, and manufacturing scalability. The ex vivo human knee joint demonstration is a preliminary feasibility signal only. Periprosthetic joint infection is a significant burden in Australia, with approximately 1–2% of primary arthroplasties complicated by PJI, managed under RACGP and AOANJRR (Australian Orthopaedic Association National Joint Replacement Registry) frameworks. Current Australian standard of care follows DAIR protocols with prolonged antibiotic courses (often rifampicin-based combinations on PBS for staphylococcal PJI). MZ-8 is not TGA-approved, not PBS-listed, and has no current pathway to Australian clinical use. Future TGA regulatory submission would require first-in-human safety data and randomised controlled trial evidence. Australian orthopaedic and infectious disease specialists should monitor this technology as a potential adjunct to surgical debridement in the medium-to-long term research horizon. Theoretically: patients with biofilm-associated periprosthetic joint infections (PJI) involving accessible joint spaces amenable to minimally invasive microrobotic navigation. Currently applicable only in preclinical research settings.

Abstract

Biofilm-associated infections present a critical therapeutic challenge due to antibiotic resistance and impaired tissue healing. Here, we present a microrobotic system (MZ-8) that integrates real-time human-steered navigation with autonomous, microenvironment-responsive therapy to actively eradicate biofilms and promote tissue regeneration. This microrobotic system features a spine-inspired structure for mechanical biofilm disruption, a pH-responsive ZIF-8 coating for immunomodulatory Zn2+ release, and closed-loop actuation under second near-infrared fluorescence guidance. In a rat model of periprosthetic joint infection, MZ-8 achieved effective biofilm removal, induced a pro-regenerative immune response by polarizing macrophages toward the M2 phenotype, and significantly enhanced tissue regeneration. Transcriptomic analysis further revealed the activation of immunomodulatory pathways and upregulation of M2-associated genes, confirming the system's sequential shift from eradication to repair. Moreover, validation in a rabbit model and human knee joint confirmed its operational feasibility under clinical imaging guidance and excellent biosafety. This work establishes that integrating physical eradication, biochemical immunomodulation, and interactive control within a single system is essential for advancing from infection clearance to functional tissue restoration. Thus, it provides a therapeutic paradigm for biofilm-associated diseases and lays a foundation for future intelligent, clinically adaptive anti-infective systems.

References

1. 1.Li, S., Mei, Y., Xu, K., Sheng, H., Chen, Y.-A., Teng, M., Xu, B., Jiang, B., Yu, C., Li, H., Zhao, S., Wang, Y., Zhang, X., Zhao, Y., Wang, Y., Wo, Y., Li, Z., Shen, S., Li, Y., Tang, M., Mei, Y., Chen, J., Huang, G., & Feng, S. (2026). Magnetically actuated microrobotic system for sequential treatment of biofilm. Proceedings of the National Academy of Sciences of the United States of America. https://doi.org/10.1073/pnas.2535216123