Nanotech News

August 8, 2005

Novel Gadolinium-Labeled Nanoparticle for MRI Applications

Combining gadolinium, which is widely used to enhance the signal obtained during magnetic resonance imaging, with a water-filled nanoparticle has yielded a construct that could dramatically increase the ability to detect small tumors in the body. This new contrast-enhancing agent, developed by Karen Wooley, Ph.D., and her colleagues at Washington University in St. Louis, is discussed in a paper published in the journal Advanced Functional Materials.

Dr. Wooley's group has been developing what she calls knedel-like nanoparticles, knedel being another word for matzo ball. These nanoparticles are composed of two types of polymer molecules that when mixed together will self-assemble into water-filled shells. (For more on self-assembly, see the July 2005 feature story by clicking here.) Once assembled, the nanoparticle constituents are then linked to one another by a simple chemical reaction that produces a durable structure. Previous work had shown that the resulting nanoparticles are non-toxic and do not trigger an immune response.

With the nanoparticles in hand, the investigators studied various means of labeling them with gadolinium ions. Gadolinium is toxic, so the labeled nanoparticles had to retain all of the label under physiological conditions. The researchers achieved this stability by first attaching gadolinium ions to a molecule known as DPTA, which they could then attach in large numbers to the nanoparticle. Chemical and physical characterization showed the gadolinium-studded nanoparticles achieved an MRI signal enhancement that far exceeded that produced by commercially available gadolinium contrast agents. The researchers are currently conducting both in vitro and in vivo assessments of their gadolinium-labeled nanoparticle.

This work, which was funded in part by the National Cancer Institute's Fundamental Technologies for Biomolecular Sensors program, is detailed in a paper titled, "Synthesis of gadolinium-labeled shell-crosslinked nanoparticles for magnetic resonance imaging applications." Investigators from the University of Queensland, Australia, also participated in this study.

An abstract is available at the journal's website.
View abstract.