Cyclic Amplified Programmable Allosteric DNA Biosensor for Enzyme-Triggered Spatially Controlled Mitochondrial Molecular Imaging.

The abnormal localization of mitochondrial human apurinic/apyrimidinic endonuclease 1 (APE1) is closely associated with tumor progression, prognosis, and drug resistance. While APE1 can localize to both the cytoplasm and nucleus as well as mitochondria. Consequently, the design of approaches with controllable localization for imaging of mitochondrial APE1 is particularly challenging. Therefore, a cyclic amplified programmable allosteric DNA biosensor (C-AP-tFNA) was developed for APE1-triggered spatially controlled mitochondrial molecular imaging. First, the interaction between the S5-S6 region of C-AP-tFNA and the mitochondria-specific localization of cytochrome c (cyt c) induces a conformational change from S5-S6 to S6, thereby enabling the activation of the AP site in S6 for cleavage by mitochondrial APE1. Second, the conformationally altered S6 can be cyclically activated and cleaved by mitochondrial APE1, leading to further configurational changes in S6 and the generation of fluorescent signals. Therefore, C-AP-tFNA enables highly sensitive and specific detection of mitochondrial APE1 in an AND-gated and cyclic amplification manner. The experimental results of this study demonstrated that C-AP-tFNA can achieve high specificity imaging of mitochondrial APE1 in tumor and inflammatory cells with high sensitivity. More importantly, C-AP-tFNA can monitor neuroblastoma drug resistance , providing a novel and effective approach for monitoring neuroblastoma drug resistance.