Such magnetoluminescent imaging agents consist of three components: a luminescent probe, a contrast agent, and a linker to combine the two. The use of lanthanide complexes as luminescent probes has the advantage of affording long luminescence lifetimes, which makes the system suitable for use in time-gated luminescence spectroscopy. Enhancing the absorption of the lanthanide terbium with a phenanthridine antenna provided an ideal luminescent probe. Magnetic iron oxide nanoparticles, known for their superior longitudinal and especially transverse relaxivities, were employed as the contrast agent, and a polyethylene glycol (PEG) linker was used to coat the luminescent probes onto the magnetic nanoparticles.
In addition to a precise luminescent probe and a contrast agent with excellent relaxivities, these systems are not cytotoxic, as, for example, systems held together by silica matrices. Moreover, the PEG coating is not as thick and is more water-permeable, which results in considerably improved cellular uptake and higher relaxivity.
More information: Valérie C. Pierre, Magnetoluminescent Agents for Dual MRI and Time-Gated Fluorescence Imaging, European Journal of Inorganic Chemistry, http://dx.doi.org/ … ic.201200045