AND-Gate Logic-Controlled Catalytic Hybridization Network for Robust Dual-Mode Fluorescence-Colorimetric Detection of Breast Cancer miRNAs

Given the low abundance of circulating miRNAs and the complexity of serum matrices, the simultaneous liquid biopsy of multiple miRNAs with both high sensitivity and accuracy remains a formidable challenge. To address these limitations, we developed a dual-mode fluorescence-colorimetric biosensor tailored for ultrasensitive, high-accuracy profiling of breast cancer-associated miRNAs. Metal-organic framework composites (PCNPt) serve as versatile signal converters capable of generating dual fluorescence and colorimetric readouts. Meanwhile, the superparamagnetic Fe₃O₄@Au nanoparticles function as magnetic capture probes that specifically enrich and isolate target miRNAs, miR-21 and miR-155, from complex serum matrices, significantly reducing background interference. Upon release, miR-21 initiates catalytic hairpin assembly, and miR-155 triggers the nuclease digestion reaction. Their simultaneous occurrence generates an AND-gated response, driving the programmed assembly between Fe₃O₄@Au and PCNPt into a catalytic hybridization network (Magnetic PCNPt Net). These assemblies are shuttled via microextraction into either acetate or phosphate buffer systems, triggering concurrent colorimetric and fluorescence readouts. The inherent self-calibration afforded by dual signaling significantly boosts the analytical sensitivity, specificity, and accuracy. We demonstrate robust quantification of multiple miRNAs in clinical serum specimens, underscoring the method's clinical applicability for breast cancer diagnostics. More broadly, this work establishes a practical framework for designing dual-signal biosensors capable of multiplexed miRNA detection, advancing the field of noninvasive molecular diagnostics.