Pseudocapacitance-Driven Ultrasensitive Biosensing via Bimetallic MOF Synergy and DNA Amplification

Ultrasensitive detection of plant pathogen DNA is crucial for early disease intervention but remains challenging due to limitations in sensitivity, specificity, and field-deployable power requirements of current methods. To address this, an innovative pseudocapacitance-driven biosensing platform is presented for the synergistic integration of bimetallic MOF synergy with cascade DNA amplification. A hierarchically porous bimetallic MOF (NiMn-MOF), engineered to leverage the synergistic interplay of dual redox-active metal centers, achieves an ultrahigh intrinsic areal capacitance (1820 μF/cm²) through synergistic intercalation pseudocapacitance. This eliminates the need for external capacitors while enabling dual-pathway signal amplification via efficient cation-insertion charge storage. Coupled with a cascaded strand displacement reaction-catalytic hairpin assembly (SDR-CHA) DNA circuit providing 10⁶-fold nucleic acid amplification, target DNA triggers DNA nanostructure reconfiguration that modulates the binding of the electroactive probe (methylene blue) to the MOF cathode. This fusion of advanced energy storage materials and nucleic acid nanotechnology establishes a self-sustaining signal transduction cascade, achieving unprecedented analytical performance: a detection limit of 0.39 fmol/L, a linear range spanning 6 orders of magnitude (5 × 10^–16–10^–9 mol/L), and exceptional single-base specificity. Validation in complex sugar cane juice matrices demonstrated high reliability (90–101% recovery) and robust operation against interferents. This work pioneers converging bimetallic MOF pseudocapacitance with enzymatic nucleic acid circuits, establishing a powerful paradigm for pseudocapacitance-driven biosensing with transformative potential for ultrasensitive, onsite molecular diagnostics.