Near-Infrared Light-Activated DNA Nanodevice for Spatiotemporal\nIn Vivo Fluorescence Imaging of Messenger RNA

Real-time\nvisualization of messenger RNA (mRNA) is essential for\ntumor classification, grading, and staging. However, the low signal-to-background\nratios and nonspatiotemporal specific signal amplification restricted\nthe in vivo imaging of mRNA. In this study, a near-infrared (NIR)\nlight-activated DNA nanodevice (DND) was developed for spatiotemporal\nin vivo fluorescence imaging of mRNA. The DND was fabricated by encapsulating\nindocyanine green (ICG) and DNA fluorescent probes within thermosensitive\nliposomes and subsequently functionalizing the liposomes with aptamers.\nThe ICG offers the “always-on” fluorescence signal,\noffering a feasible strategy for monitoring DND distribution. The\nfluorescence signal of DNA probes remains inactive (“off”\nstate) during the delivery process. Upon targeted delivery of the\nDNDs to tumor cells via aptamer recognition, the thermosensitive liposomes\ncould be dissociated by the photothermal effect induced by ICG under\nnear-infrared irradiation, thereby facilitating the release of DNA\nprobes. The DNA probes were activated (“turn on”) by\ntumor-specific thymidine kinase 1 (TK1) mRNA through toehold-mediated\nstrand displacement cascades, enabling the signal-amplified fluorescence\nimaging of mRNA. This study reveals the distinctive light-activated\nmerit and remarkable fluorescence imaging of DNDs, highlighting their\ngreat potential to promote progress in spatiotemporal resolution imaging\nof other disease-relevant RNAs in vivo.