Dead cells always accompany with live cells in vivo and in cell culture. It is important to distinguish dead cells from live cells in various biological studies. Currently, the probes for dead cells are mainly nucleic acid-intercalators, most of which have low affinity and potential toxicity to live cells. In this work, we report a novel aptameric probe (Ch4-1) for the first time, which binds cell nuclei with high affinity (apparent Kd = 6.65 ± 3.40 nM). Ch4-1 was generated by Cell-SELEX process, it was identified to target nucleoproteins in cell nuclei. As an oligonucleotide, Ch4-1 cannot penetrate the integrated cell membrane; therefore, it only binds to dead cells rather than live cells. Compared with traditional DNA-targeting nuclear dyes, Ch4-1 possesses a high affinity to the nucleus, no toxicity to live cells, and can be easily labeled with different fluorescent dyes. It was demonstrated to serve as a probe for distinguishing dead cells from live cells in apoptosis assay, as well as for the nuclear staining of tissue sections.
Keywords: aptamer; cell analysis; dead cells; nuclear probe; tissue imaging.