Magnetic torque-driven living microrobots for increased tumor infiltration

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Microbiology

Background:

• Biohybrid bacteria-based microrobots show promise for targeted cancer therapy.
• Current magnetic control strategies face scalability and feedback limitations.
• Magnetically responsive bacteria offer innate tumor-homing capabilities.

Purpose of the Study:

• To develop a scalable, feedback-independent magnetic control scheme for biohybrid microrobots.
• To enhance the transport of bacteria through biological barriers for cancer therapy.
• To improve bacterial accumulation within tumor models using magnetic actuation.

Main Methods:

• A magnetic torque-driven control scheme was developed for magnetically responsive bacteria (Magnetospirillum magneticum).
• Bacteria translocation across a vascular endothelium model was quantified.
• Bacterial colonization of 3D tumor spheroids under rotating magnetic fields was assessed.
• In vivo studies in mice evaluated bacterial tumor accumulation after intravenous injection.

Main Results:

• A fourfold increase in bacterial translocation across a vascular endothelium model was observed.
• Torque-driven surface exploration was identified as the primary transport mechanism.
• Bacteria showed up to 21-fold higher signal in tumor spheroid cores with magnetic control.
• Significantly increased bacterial tumor accumulation was demonstrated in mice.

Conclusions:

• The magnetic torque-driven control scheme is scalable and effective for enhancing bacterial microrobot transport and tumor targeting.
• This approach overcomes limitations of existing magnetic control strategies.
• The findings support the clinical feasibility of this control scheme for magnetically responsive biohybrid microrobots in cancer therapy.