Tiny robots do it all the time. They're called immune cells.
> Here we use click chemistry to attach antibiotic-loaded neutrophil membrane-coated polymeric nanoparticles to natural microalgae, thus creating hybrid microrobots for the active delivery of antibiotics in the lungs in vivo.
> Overall, these findings highlight the attractive functions of algae–nanoparticle hybrid microrobots for the active in vivo delivery of therapeutics to the lungs in intensive care unit settings.
This is fascinating, but not “robots”:
> A robot is a machine — especially one programmable by a computer — capable of carrying out a complex series of actions automatically