Graphene Can Also Function As MRI Contrast Agent

Metal-free fluorinated graphene may soon find a new use as a contrast agent for magnetic resonance imaging (MRI), according to a new study.

Developed by researchers at Rice University (Rice, Houston, TX, USA), the Indian Institute of Science (Bangalore), and other institutions, the metal-free, dual modal contrast agents are based on fluorographene quantum dots, nanoparticle disks of graphene that are decorated with fluorine atoms and organic molecules to make them magnetic. The nanoparticles can be manufactured in less than a day, using micron-sized sheets of fluorinated and oxidized graphene.

When the sheets are added to a solvent and stirred for several hours, they break into smaller pieces, or dots. According to the researchers, the fluorographene quantum dots could be particularly useful as MRI contrast agents because they could be targeted to specific kinds of tissue. An additional advantage is that since the dots are composed of carbon, hydrogen, oxygen, and fluorine, there are no signs of toxicity, as evidenced by cell culture tests. The study was published on October 21, 2016, in Particle and Particle Systems Characterization.

“There are tried-and-true methods for attaching biomarkers to carbon nanoparticles, so one could easily envision using these quantum dots to develop tissue-specific contrast agents,” said senior author Professor Pulickel Ajayan, PhD, of Rice University. “For example, this method could be used to selectively target specific types of cancer or brain lesions caused by Alzheimer’s disease. That kind of specificity isn’t available with today’s contrast agents.”

“We worked with a team from MD Anderson cancer center to assess the cytocompatibility of fluorinated graphene oxide quantum dots,” added lead author Sruthi Radhakrishnan, MSc, a graduate student at the Rice department of materials science and nanoengineering. “We used a test that measures metabolic activity of cell cultures and detects toxicity as a drop in metabolic activity. We incubated quantum dots in kidney cell cultures for up to three days and found no significant cell death in the cultures, even at the highest concentrations.”

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