Activatable Core-Shell Metallofullerene: An Efficient Nanoplatform for Bimodal Sensing of Glutathione.

Metallofullerenes have attracted considerable attention as potential novel noninvasive high-relaxivity magnetic resonance contrast agents. However, the applications of metallofullerenes as stimuli-responsive biosensors to monitor biological processes are still scarce. Herein, manganese-fullerenes core-shell nanocomposites are prepared via a facile one-pot approach to achieve GSH-activatable magnetic resonance/fluorescence bimodal imaging functions. The nanocomposites initially have a FRET-induced quenched fluorescence, and water-resisting stimulated low T1-MRI contrast. Upon exposure to GSH, collapse of the outer MnO2 shell led to reconstruction of the nanoprobes and subsequently resulted in multicolor fluorescence recovery and longitudinal (T1) relaxivity enhancement (r1 value up to 29.8 mM-1 s-1 at 0.5 T based on Mn ion). Our work demonstrates feasibility of using fullerenes to fabricate activatable probes for molecular imaging of GSH, which may promote the development of new fullerene-based stimuli-responsive multimodal probes for the detection and regulation of particular biological processes in vivo.