MnO₂ Nanotube-Based NanoSearchlight for Imaging of Multiple MicroRNAs in Live Cells

Sensitive assay and imaging of multiple low-abundance microRNAs (miRNAs) in living cells remain a grand challenge. Herein, based on polyelectrolyte-induced reduction, a facile approach has been proposed to synthesize novel MnO₂ nanotubes. Owing to the remarkably strong fluorescence quenching ability, low cytotoxicity, and excellent colloid stability, the as-prepared MnO₂ nanotubes showed great potential for simultaneous detection and imaging of multiple miRNAs in vitro and in situ in living cells for the first time. Besides, MnO₂ nanotubes can be reduced to Mn²⁺ by intracellular acid pH or glutathione, which may serve as an activatable contrast reagent for MRI. Therefore, the MnO₂ nanotube-based probes, termed "NanoSearchlight", provide a promising, multimodal imaging tool for precise and accurate diagnosis and prognosis of cancers.