Iron-based MRI contrast performs twice as well as gadolinium

Nanoscientists at Rice University in Houston have created a method to pack iron into nanoparticles to create MRI contrast agents that outperform gadolinium-based agents, according to research published in ACS Nano.

"The possibility of eliminating gadolinium exposure and getting a two-fold improvement in T1 MRI contrast performance is going to intrigue radiologists," said lead researcher, Naomi Halas, in a Rice statement. "When they hear we've done this with iron I expect they will be very surprised."

Halas and colleagues created a modified version of nanomatryoshka particles—nanoparticles she helped create 20 years ago—that contain varying layers of thickness made up of conductive metal and non-conductive silica. The particles are tuned to interact with certain light wavelengths such as near-infrared light, which can be converted into cancer-destroying heat, according to the release.

Previous work had already been done showing gadolinium chelates could be embedded in the silica layer of particles for an MRI contrast. Luke Henderson, lead author of the ACS Nano paper, however, was able to pack four-times more iron into each nanomatryoshka, which performed twice as well as gadolinium chelates, the release noted.

Additionally, Henderson was able to load various paramagnetic ions into the particles and add a final gold shell layer which protected the particles from leaching. A common problem that results in a loss of diagnostic signal, he said.

“I was looking at an old sample of nanomatryoshkas that had been in the fridge for months, and I found they were still fluorescing quite well,” he noted. “When we looked more closely at this we found the dyes were about 23 times more stable when they were inside the nanomatryoshkas.”