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Posted: May 10, 2006
Coated gadolinium nanoparticles hold promise as imaging agents
(Nanowerk News) Gadolinium ions are a popular component of agents used to improve magnetic resonance image (MRI) quality. Indeed, several groups of investigators have incorporated hundreds, even thousands, of gadolinium ions into nanoparticles targeted to tumors in an attempt to detect early stage cancer, and some of these potential imaging agents are making their way through the development process toward human clinical trials.
Operating on the principle that increasing the number of gadolinium ions loaded into a nanoparticle will improve the ability of MR imaging to detect ever smaller tumors, Michael McDonald, Ph.D., of Stanford University, and Kenneth Watkin, Ph.D., of the University of Illinois at Urbana-Champaign, have created the first water-stable nanoparticle made from gadolinium itself. The key to their success was coating nanoparticles made from gadolinium oxide with a thin coat of dextran, a naturally-occurring carbohydrate. The dextran coating prevents gadolinium from reacting chemically with water, a process that normally occurs readily. The coating also provides a surface to which tumor-targeting and therapeutic agents can be readily attached.
Reporting their work, titled "Investigations into the physiochemical properties of dextran small particulate gadolinium oxide nanoparticles" in the April issue of Academic Radiology, the two investigators describe their characterization work with the new nanoparticles. They note that the particles have an average diameter of 26 nanometers and that their magnetic properties are well-suited for use as MRI contrast agents. In fact, the dextran coating appears to increase the magnetization of the gadolinium nanoparticle compared to that of uncoated gadolinium oxide nanoparticles. The researchers note in their paper that these studies should provide a basis for developing a new generation of novel nanoparticles for use as MRI contrast agents.