A Dual-Amplification DNA Fluorescence Biosensor Based on Strand Displacement.

The development of high-sensitivity biosensing architectures with integrated signal processing capabilities remains a cornerstone of molecular diagnostics. To address the requirements for ultralow-concentration detection, we developed a programmable and modular dual-amplification DNA fluorescent biosensor (DDFB). This platform features a decoupled architecture that synergistically integrates an upstream entropy-driven catalytic (EDC) circuit for initial signal gain with a downstream hybridization chain reaction (HCR) for high-order reporting. As an enzymefree logic-capable system, the DDFB exhibited an experimentally supported linear range of 100 pM-10 nM for ARG detection, spanning two orders of magnitude, with an estimated LOD of 9.14 pM calculated using the 3σ/S criterion. Furthermore, this detection scheme enables versatile platform expansion through modular design, which exhibits superior performance in the detection of both antibiotic resistance genes (ARGs) and miR-141. Collectively, this research provides a robust, reconfigurable framework for next-generation nanobiosensors and information-processing DNA circuits.