Aptamer-Loop DNA\nNanoflower Recognition and Multicolor\nFluorescent Carbon Quantum Dots Labeling System for Multitarget Living\nCell Imaging

Visualization of multiple targets in living cells is\nimportant\nfor understanding complex biological processes, but it still faces\ndifficulties, such as complex operation, difficulty in multiplexing,\nand expensive equipment. Here, we developed a nanoplatform integrating\na nucleic acid aptamer and DNA nanotechnology for living cell imaging.\nAptamer-based recognition probes (RPs) were synthesized through rolling\ncircle amplification, which were further self-assembled into DNA nanoflowers\nencapsulated by an aptamer loop. The signal probes (SPs) were obtained\nby conjugation of multicolor emission carbon quantum dots with oligonucleotides\ncomplementary to RPs. Through base pairing, RPs and SPs were hybridized\nto generate aptamer sgc8-, AS1411-, and Apt-based imaging systems.\nThey were used for individual/simultaneous imaging of cellular membrane\nprotein PTK7, nucleolin, and adenosine triphosphate (ATP) molecules.\nFluorescence imaging and intensity analysis showed that the living\ncell imaging system can not only specifically recognize and efficiently\nbind their respective targets but also provide a 5–10-fold\nsignal amplification. Cell-cycle-dependent distribution of nucleolin\nand concentration-dependent fluorescence intensity of ATP demonstrated\nthe utility of the system for tracking changes in cellular status.\nOverall, this system shows the potential to be a simple, low-cost,\nhighly selective, and sensitive living cell imaging platform.