NANOROCKETS powered by a benign rocket fuel could one day carry drugs around the body.
Nanotubes filled with rocket fuel act like missiles, propelling themselves through liquids at eye-watering speeds. But fuels such as hydrazine are toxic so can’t be used inside the body. Now the tiny rockets have been made to work with a less toxic fuel.
Samuel Sanchez and colleagues at the Leibniz Institute for Solid State and Materials Research in Dresden, Germany, made nanotubes by rolling platinum-coated sheets of metal into tubes with the platinum on the inside.
When the team placed the tubes in a warm, weak solution of hydrogen peroxide, the platinum catalysed the decomposition of peroxide into water and oxygen. This forced bubbles of gas out of one end of the tube, generating thrust in the opposite direction (Journal of the American Chemical Society, DOI: 10.1021/ja205012j).
The result is a nanorocket that travels up to 200 times its own length per second, faster than the quickest bacteria. The team can steer the tubes using a magnetic field and control the speed by varying the temperature of the fluid.
The fuel is only 0.25 per cent peroxide but even this isn’t entirely safe. So the next step is to develop rockets that work with even less peroxide or a substance that is already present in the body, such as glucose.
This is one of the few engines that can operate in blood, urine or saliva, says Joseph Wang, a nano-engineer at the University of California, San Diego.