Supramolecular protein cage composite MR contrast agents with extremely efficient relaxivity properties

A DTPA-Gd containing polymer was grown in the interior of a heat shock protein cage resulting in T1 particle relaxivities of 4200 mM−1 sec−1 for the 12 nm particle. Relaxivity parameters were determined, and this analysis suggests that the rotational correlation time has been optimized while the water exchange lifetime is longer than optimal. This synthetic approach holds much promise for the development of next generation contrast agents and this report will aid in their design.