Scientists at the Max Planck Institute for Intelligent Systems in Germany have combined robotics and biology to equip E. coli with artificial components to build bio-hybrid robots that are expected to perform anti-cancer tasks in the future. The related research is published in the latest issue of the journal Science Advances.
E. coli are versatile swimmers that can swim in highly viscous liquids and have excellent sensing capabilities. Over the past few decades, scientists have been looking for ways to further enhance E. coli’s “superpowers” by equipping it with a variety of “weapons.
To build the robots, the team attached several nano-liposomes to each E. coli, spherical liposomes coated with indocyanine green (ICG) particles that melt when exposed to near-infrared light. The aqueous core of the liposomes is encapsulated with water-soluble chemotherapeutic drug molecules (DOX). The researchers also attached magnetic iron oxide nanoparticles to the bacteria, which act as boosters for the microbes’ high-speed motility when exposed to a magnetic field. The “string” connecting the liposomes and magnetic particles to the bacteria is a very stable and unbreakable streptavidin and biotin complex.
Once the bio-microbots are assembled where the tumor is located, the researchers explain, the near-infrared laser produces light at temperatures up to 55°C, triggering the melting process of the liposomes and releasing the drugs enclosed within them. In addition, the low pH or acidic environment also causes the liposome nanosomes to rupture, so the drug is automatically released near the tumor.
Bacteria-based bio-hybrid micro-robots with medical functions may be able to fight cancer more effectively in the future,” said study first author Burjul Akulperglu. Imagine that we inject these bacteria-based microbots into a cancer patient and magnets precisely direct the particles to the tumor. Once enough microbots surround the tumor, we irradiate it with a laser, triggering the release of the drug. For the patient, this delivery method is minimally invasive and painless, with minimal toxicity, and the drug will work where it is needed, not throughout the body.”
