Endogenous Messenger RNA-Stimulative Self-Enhanced Orthogonal Catalytic DNA Nanomachine under Near-Infrared Light Mediation for High-Performance Imaging in Living Biosamples

While the higher assay sensitivity makes orthogonal catalytic DNA nanomachines promising for imaging analysis in living biosamples, the absence of specific recognition components and the persistent "always-on" state for biomolecular identification hinder their further application. Hereby, we establish an endogenous mRNA (mRNA)-stimulative self-enhanced orthogonal catalytic DNA nanomachine mediated by near-infrared (NIR) light. Initially, a catalytic hairpin assembly and entropy-driven catalysis cascaded self-enhanced circuit is equipped with a component specific to TK1 mRNA recognition, enabling highly selective sensing initiation. Furthermore, the interior of a DNA segment is inserted with a photocleavable bond to lock the biomolecular identification, followed by NIR light mediation of up-converting luminescence to avoid premature activation of the sensing system during biodelivery. By selecting a cancer-correlated noncoding microRNA biomarker (miRNA-21) for conceptual illustration, this newly devised DNA nanomachine exhibits remarkably sensitive sensing capability with good specificity in solution detection. Delving deeper, our sensing methodology reliably achieves high-performance imaging of this low-abundance target in living biosamples, covering both the cellular and in vivo levels. This drives forward the advancement of DNA nanomachine-built fluorescent biosensors in disease diagnosis.