These Nanobots Can Swim Around a Wound and Kill Bacteria

For over a decade, Samuel Sánchez, a chemist with the Institute for Bioengineering of Catalonia, in Barcelona, has been envisioning nanobots that could carry useful payloads, like cancer drugs or antibiotics, through the body’s viscous fluids.Picture a spherical particle of silica, which functions as a chassis. The machines can actually travel around the wound and clear the infection as they go,” says ‪César de la Fuente, a bioengineer at the University of Pennsylvania who led the project with Sánchez.That matters, because drugs normally depend on diffusion, or the process of passively spreading through the body’s fluids. “The antibiotic typically just kills the bacteria around the area where you put it, but the antibiotic itself cannot really travel,” says de la Fuente.That’s why these drugs need mini motors. Sánchez envisions a nanobot delivering drugs to infections within viscous fluids like sebum, or cancers near stagnant fluids like those in the bladder. "That took some time," de la Fuente says.In the end, they devised a setup to test two important criteria: that antimicrobial micro or nanobots can treat infected mice and that their active motion plays a central role in that. Those doses had no nanobots, so to clear the infection the drug would have to diffuse on its own from one end of the wound to the other.Next, a separate set of mice received thousands of antimicrobial bots administered in a tiny droplet. The rest of the wound fared as it would have if it had received no treatment.But the nanobots carrying either antimicrobial peptide treated the entire wound and reduced the number of bacteria inside the wound 100- to 1,000-fold throughout its length, to levels that an immune system could handle.And to clinch it all, when the scientists withheld the urea fuel, they found that the antibiotic bots didn’t heal the entire infection.