A Spanish research facility has shown off a technique for “carving” nanoparticles into complex shapes. It could have practical uses in both medical testing and drug delivery.

A nanoparticle is a self-contained object that has at least one dimension smaller than 100 nanometers: that is, a stack of 10,000 would be just one millimeter wide.

The research at the Catalan Institute of Technology involved tweaking an existing technique known as the galvanic effect. In this case the researchers uses cationic gold, which is gold with some electrons removed from the atoms.

When put next to a silver cube at room temperature, the cationic gold effectively steals electrons from the silver, transforms back into ordinary gold, and attaches to the silver. Meanwhile the silver atoms that were the victim of the chemical mugging turn into ions that can be dissolved.

The researchers manipulated this process in a way that meant eventually there was just one spot on the original silver cube that hadn’t been covered in the gold. This then kicks off a second technique known as the Kirkendall effect, in which the atoms inside the silver cube begin rising to the surface, creating a void inside.

Neither of these processes are new, but the researchers were able to combine them in a particular efficient manner. It gives them much more ability to create complex shapes such as boxes and tubes.

Professor Victor Puntes told the BBC that the project was at a similar stage as with plastic when it was in the process of being created, at which point it was impossible to envision all its potential uses. One idea right now is to use different levels of hollowing out to affect the way a nanoparticle absorbs energy, thus allowing more accurate MRI-style scanning techniques. Another possibility is to create drug delivery methods such as capsules that can contain different doses of multiple drugs and release them in different ways.