"AND" or "OR" logic operations of DNA probes: Fluorescent detection and discrimination of ovarian cancer cells via dual-microRNA in complex environments.

The development of DNA logic circuits has enabled novel signal carriers for the identification of cancer cells. Addressing the limitations of single-target detection in ovarian cancer, including insufficient specificity and signal delay, this study innovatively constructs a dual-miRNA detection system based on "AND" or "OR" logic operations. In the "AND" logic pathway, both miR-221 (LOD is 0.1792 nM) and miR-96 (LOD is 0.1990 nM) are required to cooperatively trigger strand displacement amplification (SDA) for fluorescence signal activation. In contrast, the "OR" logic pathway enables signal output through either miR-221 or miR-96 (LODs are 0.1020 nM and 0.056 nM, respectively), significantly enhancing sensitivity for low-abundance samples. The core innovation lies in the hairpin structure-mediated miRNA recycling mechanism, where competitive binding allows target molecules to repeatedly participate in reactions, thereby amplifying signal efficiency. This strategy demonstrates high specificity in SKOV3 cells, and its modular design enables rapid adaptation to other miRNA combinations (e.g., miR-21/miR-155) through DNA sequence reprogramming, offering a versatile platform for multi-tumor subtyping. The approach provides new perspectives for intelligent, portable biosensing and bioanalytical applications.