Using a standard AFM instrument, the scientists have applied the method to a variety of magnetic nanoparticles, including tiny superparamagnetic materials, and core:shell particles. The aim of the work is to further develop biological applications of magnetic nanoparticles. "We want to be able to locate the nanoparticles, with specificity for their magnetic properties, in or on human cells," explained Dr Peter Eaton, corresponding author.

One long-standing goal of nanomagnetics has been the use of magnetic nanoparticles for therapeutic applications. The idea is that particles specifically target cancer cells and are then used to heat the cells and kill them. In order to develop these applications, researchers need tools that can locate the tiny magnetic particles to see if they are really finding their targets. The group of Dr Eaton, including PhD student Cristina Neves from Requimte, wants to develop these tools.

"One of the problems people have when working with biological samples is contamination. Finding 40 nm particles in a specimen that also contains the various materials needed by the cells is tough. In our work, we show methods that will be useful to distinguish the magnetic particles from signals that relate to all of that other stuff," said Eaton. "Even better, we were astonished to find that we could detect the particles even with the probe hundreds of nanometres away from them. This means that MFM might be capable of detecting the particles inside the cells, and that's where we are going next."