An AND-gate dual-responsive fluorescent sensing strategy for HClO and APE1 toward selective cancer cells recognition

The global cancer burden is continuously increasing, and existing clinical approaches fail to adequately meet the demand for highly sensitive and accurate ultra-early diagnosis. Hypochlorous acid (HClO) and apurinic/apyrimidinic endonuclease 1 (APE1) have been found to be abnormally overexpressed in cancer cells, rendering them suitable targets for cancer cell detection. Consequently, this study developed a dual-responsive fluorescent sensing system (DRFS) for HClO and APE1 based on the toehold-mediated strand displacement (TMSD) signal amplification strategy to achieve specific recognition of cancer cells. This system employs two hairpin DNA for the specific recognition of HClO and APE1, respectively, in which a three-stranded complex (named as NT) acts as the fluorescent reporter. In the presence of both targets, the system exhibits a significantly enhanced fluorescent signal. Notably, DRFS enables highly sensitive and specific dual-target detection, with limits of detection as low as 4.69 nM for HClO and 0.06 U/mL for APE1. The accuracy of DRFS in complex sample was validated by serum recovery experiments. Additionally, the system was used to distinguish cancer cells from normal cells, with satisfactory results. Overall, DRFS offers high performance, efficiency, ease of operation, and low cost, enabling the precise and reliable identification of cancer cells. These advantages and capabilities provide DRFS strong potential for early cancer diagnosis and biochemical analysis.