Anthony King in Nature:
Cancer drugs usually take a scattergun approach. Chemotherapies inevitably hit healthy bystander cells while blasting tumours, sparking a slew of side effects. It is also a big ask for an anticancer drug to find and destroy an entire tumour — some are difficult to reach, or hard to penetrate once located. A long-dreamed-of alternative is to inject a battalion of tiny robots into a person with cancer. These miniature machines could navigate directly to a tumour and smartly deploy a therapeutic payload right where it is needed. “It is very difficult for drugs to penetrate through biological barriers, such as the blood–brain barrier or mucus of the gut, but a microrobot can do that,” says Wei Gao, a medical engineer at the California Institute of Technology in Pasadena.
Among his inspirations is the 1966 film Fantastic Voyage, in which a miniaturized submarine goes on a mission to remove a blood clot in a scientist’s brain, piloted through the bloodstream by a similarly shrunken crew. Although most of the film remains firmly in the realm of science fiction, progress on miniature medical machines in the past ten years has seen experiments move into animals for the first time.