Endogenous\nMessenger RNA-Stimulative Self-Enhanced\nOrthogonal Catalytic DNA Nanomachine under Near-Infrared Light Mediation\nfor High-Performance Imaging in Living Biosamples

While the higher assay sensitivity makes orthogonal catalytic\nDNA\nnanomachines promising for imaging analysis in living biosamples,\nthe absence of specific recognition components and the persistent\n“always-on” state for biomolecular identification hinder\ntheir further application. Hereby, we establish an endogenous mRNA\n(mRNA)-stimulative self-enhanced orthogonal catalytic DNA nanomachine\nmediated by near-infrared (NIR) light. Initially, a catalytic hairpin\nassembly and entropy-driven catalysis cascaded self-enhanced circuit\nis equipped with a component specific to TK1 mRNA recognition, enabling\nhighly selective sensing initiation. Furthermore, the interior of\na DNA segment is inserted with a photocleavable bond to lock the biomolecular\nidentification, followed by NIR light mediation of up-converting luminescence\nto avoid premature activation of the sensing system during biodelivery.\nBy selecting a cancer-correlated noncoding microRNA biomarker (miRNA-21)\nfor conceptual illustration, this newly devised DNA nanomachine exhibits\nremarkably sensitive sensing capability with good specificity in solution\ndetection. Delving deeper, our sensing methodology reliably achieves\nhigh-performance imaging of this low-abundance target in living biosamples,\ncovering both the cellular and <i>in vivo</i> levels. This\ndrives forward the advancement of DNA nanomachine-built fluorescent\nbiosensors in disease diagnosis.