Researchers from Quingdou University of Science and Technology in China developed a method to produce “supermagnets” that could one day be used as targeted drug delivery vehicles. The team’s work was published in Physics Letters A. 

Some magnetic materials are small enough that their magnetization randomly flips according to temperature; when scientists apply a magnetic field to these crystals, the material becomes almost as strongly magnetic as an ordinary fridge magnet. This type of magnetism, called superparamagnetism, is the strongest known type of magnetism.

Superparamagnetic particles could be directed to a tumor using a magnetic field, making them ideal vehicles for drug delivery. The supermagnets’ tiny size previously made them impossible to guide precisely, but the Quingdou team’s particles are large enough to control with external fields.

The researchers said that the high temperature and high pressure under which the crystals form create irregularities in the crystal lattice of the supermagnets. These irregularities are responsible for the magnetic properties that make the supermagnets a potential method of drug delivery. Most magnetic crystals of a similar size that are grown at lower temperature and normal pressure conditions are only weakly magnetic.

“The largest superparamagnetic materials that we have been able to make before now were clusters of nanocrystals that were together about a thousand times smaller than these,” co-author Kezheng Chen said in prepared remarks. “These larger crystals are easier to control using external magnetic fields, and they will not aggregate when those fields are removed, which will make them much more useful in practical applications, including drug delivery.