Single DNA hairpin nanowire based on self-hybridization chain reaction for sensitive ATP detection.

Hybridization chain reaction (HCR), which typically consists of two hairpins for signal amplification, has emerged as a versatile tool in bioanalytical applications. Here, a novel HCR nanowire based on a single DNA hairpin structure is reported. The hairpin stem is rationally engineered with a palindromic sequence, which enables a self-hybridization chain reaction (SHCR) upon the introduction of the initiator DNA strand. Compared to the conventional two hairpin-based HCR nanowire, the single DNA hairpin-based SHCR nanowire achieves nearly a two-fold improvement in the signal-to-noise ratio and exhibits better selectivity for single-base mismatch. By integrating the initiator DNA strand with adenosine triphosphate (ATP) aptamer, the single DNA hairpin-based nanowire has been applied for sensitive ATP detection, capable of monitoring ATP both in living cells and that released from dead cancer cells post-radiotherapy. The SHCR nanowire we proposed here has significantly simplified the sequence design of HCR and holds promise as a potential alternative to the conventional HCR nanowire.