MRI/Fluorescence bimodal amplification system for cellular GSH detection and tumor cell imaging based on manganese dioxide nanosheet

Here, we report a novel magnetic resonance imaging (MRI)/fluorescence bimodal amplification platform for the detection of glutathione (GSH) on the basis of redoxable manganese dioxide (MnO(2)) nanosheets, which can be readily applied as a DNA nanocarrier, fluorescence quencher, and intracellular GSH-activated MRI contrast agent. The binding of aptamers that absorbed on the MnO(2) nanosheets to their target can facilitating the endocytosis of target-nanoprobes. Once endocytosed, the MnO(2) nanosheets can react with cellular GSH, resulting in the disintegration of nanosheets to generate plenty of Mn(2+) ions for MRI and releases the primers which were adsorbed on the MnO(2) nanosheets. Then the rolling circle amplification (RCA) reaction was initiated to amplify the fluorescence signal. In addition, after treatment with GSH, the MnO(2) nanosheets were reduced and then most of the fluorescence was recovered. Therefore, this MnO(2) nanoprobe exhibits excellent selectivity, suggesting a potential detection platform for analyzing the glutathione level in cells.