NIR Light-Propelled Janus-Based Nanoplatform for Cytosolic-Fueled microRNA Imaging

Various nanoplatforms have been developed to visualize intracellular microRNAs (miRNAs) because of their clinical significance in tumor progression and diagnosis. However, the diffusion-limited motion of the nanoplatforms penalizes the miRNA imaging efficiency in cells. Herein, we fabricated a near-infrared (NIR) light-propelled Janus-based nanoplatform to advance the imaging response. The Janus nanomotor covered with an Au half-shell was loaded by the endocytosis adjuvant of the MnO₂ nanosheet for delivering a miRNA-responsive hQN (hairpin DNA quadrangular nanostructure) probe with a catalyzed hairpin assembly (CHA). Once the nanoplatform entered into cells, the MnO₂ nanosheet was degraded to Mn²⁺ by endogenous fuels (such as glutathione) to release the hQN probe. The NIR light irradiation of the nanoplatform generated a heat gradient and thus propelled motion of the nanoplatform. This process accelerated the intracellular reaction of the hQN probe with miRNAs to trigger the cascade CHA amplification with an enhanced fluorescence readout.