Tumor targeting by computer controlled guidance of Magnetotactic Bacteria acting like autonomous microrobots

This paper reports the successful navigation of Magnetotactic Bacteria (MTB) towards regions located inside a solid tumor using a computer controlled set of magnetic coils. MTB uses two flagella bundles connected to rotary molecular motors as a propulsion system enabling them to reach swimming velocities of 300µm·s⁻¹ without external source of power. Acting like autonomous microrobots, they can be remotely controlled by an appropriate magnetic guidance system as their swimming direction is predominantly determined by the direction of the ambient magnetic field. In order to cope with the harsh environment of the solid tumor and to bypass the lack of knowledge of the internal vessels architecture forming the route to the tumor, fundamental MTB motion properties are taken into account in addition to their ability to swim along the magnetic field. The studies revealed the presence of these bacteria in the necrotic zone of a solid tumor. Preliminary results suggest that not only the magnetic guidance can help enhancing the uniform distribution of MTB inside the tumor for therapeutic or diagnostic purposes, but the experimental data showed that they could perform accurately and efficiently under computer control, many of the tasks previously envisioned for future synthetic microrobots of only 1 to 2 micrometers in diameter and designed to operate in the human microvascular network.