Highly sensitive detection of cancer cells via split aptamer mediated proximity-induced hybridization chain reaction

Highly sensitive detection of cancer cells is of great importance for evaluating cancer development and improving survival rates. Here, we developed a split aptamer mediated proximity-induced hybridization chain reaction (HCR) strategy to meet this purpose. In this strategy, two split aptamer initiator probes, Sp-a and Sp-b, and two HCR hairpin probes, H1 and H2 were designed. The split aptamer initiator probes contained two components, split aptamer domains being responsible for target recognition, and the split initiator parts serving as the HCR promoter. In the presence of target cells, Sp-a and Sp-b would self-assemble on the cell surfaces, allowing the formation of an intact nicked initiator to activate the HCR reaction. Benefit from low background split aptamers and HCR amplification, this strategy presented high sensitivity in quantitative detection with a detection limit of 18 cells in 150 μL of binding buffer. Moreover, the approach exhibited excellent specificity to target cells in 10% fetal bovine serum and mixed cell samples, which was favorable for clinical diagnosis in complex biological environment. In addition, by changing the split aptamers attached to the split initiator, the proposed strategy can be expanded to detect various kinds of target cells. It may provide a novel and useful applicable platform for the sensitive detection of cancer cells in biomedicine and tumor-related studies.