When triggered, the molecules rapidly drilled through the cell membranes.

Dr James Tour, a member of the international team from Rice University in Houston, US, said: "These nanomachines are so small that we could park 50,000 of them across the diameter of a human hair, yet they have the targeting and actuating components combined in that diminutive package to make molecular machines a reality for treating disease.

"In this study we have shown that we can drill into cells, animal cells, human cells using these nanomachines, they will attach to the surface and then a light will be shone upon them and they will drill right into the cell.

"For many years I never had envisioned the nanomachines being used medically, I though they were way too small, because they are much much smaller than a cell, but now this work has really changed my thoughts on this and I think therapeutically this will be a whole new way to treat patients, it's going to be an excellent application for cancer treatment, not just for killing of cells but for the treatment of cells, interacting with the human body using molecular machines."