Activatable Fluorescence/MRI Bimodal Platform for Tumor Cell Imaging via MnO_2 Nanosheet-Aptamer Nanoprobe

摘要

A novel dual-activatable fluorescence/MRI bimodal platform is designed for tumor cell imaging by using a redoxable manganese dioxide (MnO_2) nanosheet-aptamer nanoprobe. The redoxable MnO_2 nanosheet acts as a DNA nanocarrier, fluorescence quencher, and intracellular glutathione (GSH)-activated MRI contrast agent. In the absence of target cells, neither fluorescence signaling nor MRI contrast of the nanoprobe is activated. In the presence of target cells, the binding of aptamers to their targets weakens the adsorption of aptamers on the MnO_2 nanosheets, causing partial fluorescence recovery, illuminating the target cells, and also facilitating the endocytosis of nanoprobes into target cells. After endo-cytosis, the reduction of MnO_2 nanosheets by GSH further activates the fluorescence signals and generates large amounts of Mn~(2+) ions suitable for MRI. This platform should facilitate the development of various dual-activatable fluorescence/MRI bimodalities for use in cells or in vivo.