Bacteria that make tiny magnetic particles could be harnessed to create drugs that home in on a specific site in the body. The particles come ready-wrapped in their own biological membrane, so molecules such as anticancer drugs could easily be attached.

Doctors could then direct the drugs to a certain area of the body using magnets, says Andrew Harrison of the University of Edinburgh, UK. Confining the medicine where it’s needed could, in theory, reduce the harrowing side-effects of chemotherapy.

With genetic modification, the bacteria could improve the yield of magnetic particles, leading to effective targeted drug delivery.