Sperm, those tenacious, single-minded swimmers and deliverers of life, are being enlisted as “spermbots” by scientists to act as biological motors capable of transporting drugs, genes and even other sperm to help treat a variety of medical issues.
Researchers at Dresden Institute for Integrative Nanosciences were looking for a way to propel micro-robots through bodily fluids safely. Like all moving robots, micro-robots need fuel, but it can be toxic to a human body. So the scientists started brainstorm about safer alternatives.
“We thought of using a powerful biological motor to do the job instead and we came up with the flagella of a sperm cell, which is physiologically less problematic,” professor Oliver G. Schmidt, the Institute’s Director, told Gizmag. Sperm cells are easily available, harmless and efficient at swimming through bodily fluids.
To create these tiny robots, the scientists first had to catch a few. First, they designed microtubes, which are essentially thin sheets of titanium and iron — which have a magnetic property — rolled into conical tubes, with one end wider than the other. Next, they put the microtubes into a solution in a Petri dish and added bovine sperm cells, which are similar size to human sperm. When a live sperm entered the wider end of the tube, it became trapped down near the narrow end. The scientists also closed the wider end, so the sperm wouldn’t swim out. And because sperm are so determined, the trapped cell pushed against the tube, moving it forward.
Next, the scientists used a magnetic field to guide the tube in the direction they wanted it to go, relying on the sperm for the propulsion.
Each spermbot is capable of traveling up to 100 micrometers per second, which is similar to a 6-foot-tall human swimming 160 ft (50 meters) in 14 seconds.
The quick swimming spermbots could use controlled from outside a person body to deliver payloads of drugs and even sperm itself to parts of the body where its needed, whether that’s a cancer tumor or an egg.
Credit: IFW Dresden, Germany