NIR Photocontrolled Fluorescent Nanosensor under a Six-Branched DNA Nanowheel-Induced Nucleic Acid Confinement Effect for High-Performance Bioimaging

Although DNA nanotechnology is a promising option for fluorescent biosensors to perform bioimaging, the uncontrollable target identification during biological delivery and the spatially free molecular collision of nucleic acids may cause unsatisfactory imaging precision and sensitivity, respectively. Aiming at solving these challenges, we herein integrate some productive notions. On the one hand, the target recognition component is inserted with a photocleavage bond and a core-shell structured upconversion nanoparticle with a low thermal effect is further employed to act as the ultraviolet light generation source, under which a precise near-infrared photocontrolled sensing is achieved through a simple external 808 nm light irradiation. On the other hand, the collision of all of the hairpin nucleic acid reactants is confined by a DNA linker to form a six-branched DNA nanowheel, after which their local reaction concentrations are vastly enhanced (similar to 27.48 times) to induce a special nucleic acid confinement effect to guarantee highly sensitive detection. By selecting a lung cancer-associated short noncoding microRNA sequence (miRNA-155) as a model low-abundance analyte, it is demonstrated that the newly established fluorescent nanosensor not only presents good in vitro assay performance but also exhibits a high-performance bioimaging competence in live biosystems including cells and mouse body, propelling the progress of DNA nanotechnology in the biosensing field.

Automated summary

DNA nanotechnology has potential for fluorescent biosensors in bioimaging, but uncontrollable target identification and molecular collision of nucleic acids may affect imaging precision and sensitivity. To address these challenges, innovative approaches are integrated, such as incorporating a photocleavage bond and using core-shell upconversion nanoparticles as an ultraviolet light source for near-infrared photocontrolled sensing. Additionally, a DNA linker is employed to confine the collision of nucleic acid reactants, leading to enhanced local reaction concentrations and highly sensitive detection. The developed fluorescent nanosensor shows excellent assay performance and bioimaging competence in live biosystems, advancing the field of DNA nanotechnology in biosensing.