Activatable magnetic resonance imaging (MRI) contrast agents are highly sought after for their capacity to report on biochemical processes rather than strictly anatomy. However, most previously reported �smart� agents are limited by lack of reversibility. We have developed a T2 agent based on magnetic nanoparticles functionalized with �molecular switches�, which exhibits MR signal modulation as a result of light stimulus. These �switches�, from the spiropyran family, change conformation between hydrophilic and hydrophobic isomers in response to visible or UV light. This isomerization induces controlled aggregation or dispersion of the nanoparticles thus varying the signal intensity in MRI. Initial results indicate a 33.7% decrease in T2 relaxation time upon light irradiation and corresponding aggregation of nanoparticles as evidenced by size measurements. In addition, reversibility is a distinct advantage of this system that may translate to dynamic monitoring using MRI. Promising current and future applications for these light-responsive agents will be presented.

Development and utility of a light-responsive MRI T2 agent

240th National Meeting (2010)

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