Multiresponsive Nanoprobes for Turn-On Fluorescence/19F MRI Dual-Modal Imaging.

Multiresponsive nanoprobes are highly desirable for low background and highly sensitive imaging in biomedical applications. Herein, we design a glutathione (GSH)/pH dual-responsive nanoprobe capable of both fluorescence imaging in cells and 19F magnetic resonance imaging (19F MRI) in deep tissue, by encapsulating manganese oleate (Mn(OA)2) on the surface of fluorinated fluorescent quantum dots (F-ZnS:Mn2+). In this approach, Mn(OA)2 serves as an efficient quencher of both fluorescence and 19F MRI signal. Both the fluorescence and 19F MRI signal can be turned on by introducing glutathione (GSH) that breaks up the Mn-O bonds within Mn(OA)2 under weak acidity conditions (e.g., pH 6.0). The imaging results in cells and mice suggest that this novel strategy can offer a promising nanoprobe for turn-on fluorescence/19F MRI dual-modal tumor imaging.