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.