NIR–II DNA Nanodevice for Spatiotemporal MicroRNAs Imaging Based on “and” Logic‐Gate Strategy

The precise detection of multiple microRNAs (miRNAs) is of great significance to the classification of various cell subtypes. However, miRNA detection is hindered by signal leakage, false‐positive signals and low expression of miRNAs. Herein, a DNA nanodevice in the second near infrared region (NIR‐II, 1000‐1700 nm) (DND‐II) is developed for dual miRNAs bioimaging based on “AND” logic‐gate signal amplification strategy. The spatiotemporally controlled logic‐gate‐based DND‐II is fabricated by thermosensitive liposomes integrated with the second near‐infrared DNA probes. In particular, the “always‐on” photoacoustic signal of DNA probes provided an additional imaging tool to monitor the distribution of DND‐II in vivo. When both miRNAs are present, the DNA probes generated a “turn on” fluorescent signal through DNA logical analysis and molecular computation, further triggering an entropy‐driven dual‐cycle fluorescence signal amplification. The spatiotemporal DND‐II provides a powerful platform for early diagnosis and photothermal ablation of different subtypes of tumor cells.