Institute for Translational Medicine, Department of Health Sciences and Technology, ETH Zurich, CH-8092, Zurich, Switzerland.
Nat Commun. 2024 Mar 9;15(1):2160. doi: 10.1038/s41467-024-46407-4.
Rotating magnetic fields enable biomedical microrobots to overcome physiological barriers and promote extravasation and accumulation in tumors. Nevertheless, targeting deeply situated tumors requires suppression of off-target actuation in healthy tissue. Here, we investigate a control strategy for applying spatially selective torque density to microrobots by combining rotating fields with magnetostatic selection fields. Taking magnetotactic bacteria as diffuse torque-based actuators, we numerically model off-target torque suppression, indicating the feasibility of centimeter to millimeter resolution for human applications. We study focal torque application in vitro, observing off-target suppression of actuation-dependent effects such as colonization of bacteria in tumor spheroids. We then design and construct a mouse-scale torque-focusing apparatus capable of maneuvering the focal point. Applying this system to a mouse tumor model increased accumulation of intravenously injected bacteria within tumors receiving focused actuation compared to non-actuated or globally actuated groups. This control scheme combines the advantages of torque-based actuation with spatial targeting.
旋转磁场使生物医学微型机器人能够克服生理障碍，并促进在肿瘤中的渗出和积累。然而，针对深部肿瘤需要抑制在健康组织中的非靶向驱动。在这里，我们通过将旋转磁场与静磁场选择场相结合，研究了一种应用空间选择性扭矩密度的控制策略。以趋磁细菌作为弥散扭矩型执行器，我们通过数值模拟来抑制非靶向扭矩，这表明对于人体应用，厘米到毫米的分辨率是可行的。我们在体外研究了聚焦扭矩的应用，观察到了非靶向抑制作用，例如细菌在肿瘤球体中的定植。然后，我们设计并构建了一个能够操纵焦点的鼠标级扭矩聚焦装置。将该系统应用于小鼠肿瘤模型中，与未受刺激或全局刺激的组相比，接受聚焦刺激的肿瘤内静脉注射细菌的积累增加。该控制方案结合了基于扭矩的驱动和空间靶向的优势。
