Extracellular ATP-activated hybridization chain reaction for accurate and sensitive detection of cancer cells

Accurate and sensitive detection of cancer cells is of significant importance for early diagnosis and treatment of cancer. Here, we developed an extracellular ATP-activated hybridization chain reaction (HCR) amplification strategy to meet this purpose. This strategy relies on three DNA probes, Apt-trigger, H1-ATP aptamer duplex and hairpin H2. The Apt-trigger probe consists of two components: an aptamer sequence for specific recognition of the target cells, and a trigger sequence for the HCR assembly. The duplex structure of H1-ATP aptamer causes the toehold in hairpin H1 to be hidden, preventing the strand-displacement reaction between hairpin H1 and Apt-trigger. Upon activation with ATP, the ATP aptamer will bind to ATP to dissociate from hairpin H1, thus leading to an Apt-trigger-induced strand-displacement reaction and subsequent HCR with hairpin H2 on the target cell surface. Benefiting from aptamer recognition and ATP-activated HCR amplification, this strategy can not only perform sensitive quantitative analysis with a detection limit of 25 cells in 200 μL of binding buffer, but also show desirable specificity and accuracy for identifying target cells from control cells and mixed cell samples. Importantly, this method retains stable and good performance for target cell detection in 10% fetal bovine serum, demonstrating great potential for clinical diagnosis in complex biological matrices. Furthermore, this strategy can be adapted to detect various types of cancer cells by changing the corresponding aptamer sequence.