A rapid, adaptative DNA biosensor based on molecular beacon-concatenated dual signal amplification strategies for ultrasensitive detection of p53 gene and cancer cells.

The cancer diagnosis with single level of biomarkers suffers from limitation of insufficient accuracy. Hence, developing sensitive, rapid and adaptative analytical strategies for double-level biomarkers are essential for improving the accuracy of clinical cancer diagnosis at early stage. Herein, a DNA biosensor was established based on the catalytic hairpin assembly-mediated Y-junction nicking enzyme assisted signal amplification (CHA-YNEASA) circuits, where the two circuits were concatenated by molecular beacon (MB). In absence of target, both the CHA and YNEASA circuits were effectively hindered because of MB's outstanding ability to control signal background. In presence of target, the initiated CHA circuits made enzyme recognition sequences in close proximity to the assisted sequences to open MB, leading to further trigger the YNEASA circuits. Due to the unique design of dual signal amplification strategies, CHA-YNEASA circuits significantly shorten the reaction time, and improve signal-to-background ratio as well as facilitate the analysis process. It was demonstrated that a high sensitivity with limit of detection (LOD) of 0.9 pM for p53 gene detection was obtained just within 23 min by the proposed DNA biosensor. Moreover, mismatched p53 gene at nucleic acid level was effectively discriminated and strong anti-interference capability was achieved. Noticeably, the DNA biosensor was adaptative for designing a cytosensor at cell level using hairpin DNA, containing MUC1 aptamer and initiation strand of CHA-YNEASA circuits, as switch based on modularity principle. The cytosensor is able to measure MUC1 positive breast cancer cells (MCF-7) with the LOD as low as 100 cells/mL. Excellent specificity for MUC1 negative cells, and good anti-interference capability in 10% fetal bovine serum (FBS) were observed by the cytosensor. Therefore, the proposed DNA biosensor is a sensitive, rapid, adaptative platform for detection of double-level biomarkers, offering novel strategy applied for clinical cancer diagnosis.