Nanoparticles on the horizon as MRI contrast agents
Magnetite nanoparticles should have great potential as high-performance MRI contrast agents for cell or molecular imaging and diagnostic applications, according to a study published online in the October issue of the journal Chemical Communications.

Wei Cai and co-workers at the Harbin Institute of Technology, in Harbin, China, developed a new class of monodisperse, water-soluble magnetite nanoparticles using a polyol process and investigated its potential as an MRI contrast agent.

Researchers synthesized the magnetite nanoparticles by heating an iron(III) salt in triethylene glycol at elevated temperature without any surfactants. This reaction forced the magnetite to play “a triple role as high-boiling solvent, reducing agent and stabilizer to efficiently control the particle growth and prevent interparticle aggregation.”

For magnetite nanoparticles to be useful for imaging, the contrast agent should be non-toxic, water soluble and not prone to aggregation. High crystallinity and a uniform size distribution also improve the reproducibility and effectiveness, according to Cai.

The aqueous solutions of the magnetite nanoparticles were measured on a clinical 1.5-T MRI scanner to determine the MR signal enhancement effects.

According to the results, “MRI measurements indicate the nanoparticles have the desired relaxivity values for MR signal enhancement. In vitro experiments show that the nanoparticles are biocompatible and are taken up readily by glioma cells, suggesting that these magnetite nanoparticles have potential as MRI contrast agents for biomedical research and clinical diagnosis.”

Cai said that the synthesis “provides an alternative approach to the traditional co-precipitation method for large scale preparation of magnetic nanoparticles for biomedical applications.” The synthesized magnetite nanoparticles also had high uptake by cancer cells and preliminary experiments have indicated that these nanoparticles could also be useful as a biomarker for imaging cancer cells, he said.

The study was supported by the National Natural Science Foundation of China.