Creating a new generation of contrast agents 

Imaging with the aid of a magnet resonance camera often uses a contrast agent that contains gadolinium, a rare earth metal with good magnetic properties. In recent years, however, concerns have been raised by American public health authorities that gadolinium, even in small amounts, may have detrimental effects on the human body. For this reason, much work has been done around the world to discover the next generation of contrast agents, which will not only give images with high contrast but also be less harmful for the body. Magnetic resonance imaging in itself is completely pain-free and does not harm the body in any way.

Antioxidant properties

Peter Eriksson recently presented his doctoral thesis in the Molecular Surface Physics and Nanoscience Division, Linköping University, with research conducted in the borderland between physics, chemistry, biology and imaging science. He demonstrates in the thesis how integrating gadolinium into the crystal structure of nanoparticles of cerium oxide produces particles that both have antioxidant properties and give higher contrast.

Oxidative stress caused by an excess of free oxygen radicals is considered to be one of the causes of inflammatory diseases such as Alzheimer and Parkinson’s. There is thus considerable interest in developing nanoparticles with antioxidant properties, such that these particles can scavenge the free oxygen radicals.
“The antioxidant properties originate from the ability of cerium to undergo redox-reactions with free oxygen radicals, while the contrast-enhancing properties needed for MRI arise from the magnetic properties of gadolinium”, Peter Eriksson explains.
In a subsequent step he has embedded nanoparticles of gadolinium and cerium oxide in a soft protective shell of dextran, in order to protect the core and increase biocompatibility.

Next generation of contrast agent

“Rare earth metals, such as gadolinium and cerium, are interesting since their unique electrical, magnetic and optical properties depend on particle size. We can use modern Peter Eriksson Photo credit Anna Nilsennanotechnology to combine them and produce particles with tailor-made properties. We have shown here that nanoparticles of cerium and gadolinium have both antioxidative properties and good diagnostic imaging properties. This makes them good candidates to be the next generation of contrast agent for MRI”, says Peter Eriksson.

Not only are the nanoparticles of cerium oxide antioxidant: they are useful carriers of other rare earth metals. Experiments are now being conducted to add functional groups to the nanoparticles, tailored to seek out a specific target, such as diseased tissue. The principle is that the nanoparticles should not only be anti-inflammatory, but also contribute to high contrast in the specific tissue during MRI.

Main funding bodies for the research are the Swedish Research Council, the strategic investment in advanced functional materials, AFM, at Linköping University, the Knut and Alice Wallenberg Foundation, and the Centre in Nanoscience and Technology (CeNano) at Linköping University.

The thesis: Cerium Oxide Nanoparticles and Gadolinium Integration, Synthesis, Characterization and Biomedical Applications, Peter Eriksson, Department of Physics, Chemistry and Biology, Linköping University, 2019
Principal supervisor has been Professor Kajsa Uvdal.

Translated by George Farrants