Biohybrid bacteria–based microrobots are increasingly recognized as promising externally controllable vehicles for targeted cancer therapy. A range of bacteria, shown for Magnetospirillum magneticum as a magnetically responsive model organism was used for targeted drug delivery. It was observed a fourfold increase in translocation of magnetically responsive bacteria across a model of the vascular endothelium and found that the primary mechanism driving increased transport is torque-driven surface exploration at the cell interface. Using spheroids as a three-dimensional tumor model, fluorescently labeled bacteria colonized their core regions with up to 21-fold higher signal in samples exposed to rotating magnetic fields. In addition to enhanced transport, it was demonstrated that this control scheme offers further advantages, including the possibility for closed-loop optimization based on inductive detection, as well as spatially selective actuation to reduce off-target effects. Last, after systemic intravenous injection in mice, significantly increased bacterial tumor accumulation was shown, supporting the feasibility of deploying this control scheme clinically for magnetically responsive biohybrid microrobots.
T. Gwisai, N. Mirkhani, M. G. Christiansen, T. Nguyen, V.Ling, S. Schuerle, Magnetic torque–driven living microrobots for increased tumor infiltration. Science Robotics 2022, 7,