Release activation of iron oxide nanoparticles: (REACTION) A novel environmentally sensitive MRI paradigm
Article first published online: 28 FEB 2011
Copyright © 2011 Wiley-Liss, Inc.
Magnetic Resonance in Medicine
Volume 65, Issue 5, pages 1253–1259, May 2011
How to Cite
Granot, D. and Shapiro, E. M. (2011), Release activation of iron oxide nanoparticles: (REACTION) A novel environmentally sensitive MRI paradigm. Magn Reson Med, 65: 1253–1259. doi: 10.1002/mrm.22839
- Issue published online: 15 APR 2011
- Article first published online: 28 FEB 2011
- Manuscript Accepted: 20 DEC 2010
- Manuscript Revised: 18 NOV 2010
- Manuscript Received: 16 JUL 2010
- iron oxide;
- contrast agents;
Smart contrast agents for MRI-based cell tracking would enable the use of MRI methodologies to not only detect the location of cells but also gene expression. Here, we report on a new enzyme/contrast agent paradigm which involves the enzymatic degradation of the polymer coating of magnetic nanoparticles to release encapsulated magnetic cores. Cells were labeled with particles coated with a polymer, which is cleavable by a specific enzyme. This coat restricts the approach of water to the particle, preventing the magnetic core from efficiently relaxing protons. The reactive enzyme was delivered to cells and changes in cellular T2 and T2* relaxation times of ∼ 35% and ∼ 50% were achieved in vitro. Large enhancements of dark contrast volume (240%) and contrast-to-noise ratio (48%) within the contrast regions were measured, in vivo, for cells co-labeled with enzyme and particles. These results warrant exploration of genetic avenues toward achieving release activation of iron oxide nanoparticles. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.