Scientists have created the first ever “sperm-based biobots” by trapping single sperm cells inside metal nanotubes and remotely controlling their direction using magnets.

The resulting biobot (a ‘biological robot’, referring to a bacterium or cell which has been programmed to behave in a certain way) could be put to a range of uses, including delivering drugs to a specific target in the body or fertilising an egg, reports New Scientist.

The experiments have been led by Oliver Schmidt at the Institute for Integrative Nanosciences in Dresden, Germany. Schmidt and his team created magnetic nanotubes 50 microns long by 5 to 8 microns in diameter and dropped these into a fluid containing bull sperm.

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The tubes, which are narrower at one end to stop the sperm from escaping, can then be rotated by using magnetic fields. The tail-like flagellum of the sperm cell sticks outside the end of the tube and powers the biobot around the fluid like an outboard motor.

Schmidt told New Scientist's MacGregor Campbell that sperm cells were an attractive option for this sort of work as they do not require an external power source, are harmless to the human body, and are adept at swimming through viscous liquids.

Previous experiments in this vein have focused on controlling bacteria by altering the chemicals in their environment, but Schmidt’s work is the first to directly ‘harness’ a microorganism in this fashion.

A paper outlining his research can be found in Advanced Materials entitled ‘Development of S perm-Flagella Drive Micro-Bio-Robot’.