ON/OFF-switchable magneto-controlled electrochemical platform with periodic modulation for tunable enzymatic reaction and highly sensitive HRP detection

Biocatalytic reactions within organisms are contingent on sophisticated regulatory mechanisms, the precise control and regulation of which are of paramount importance. Magneto-controlled enzyme reaction, as a powerful regulate tool, enables the activation or inhibition of catalytic processes through external magnetic field signals. These reactions are of particular interest for advanced bioelectronic devices with tunable biosensing capabilities and novel bioelectronic applications. Here in, we report an ON/OFF-switchable magneto-controlled electrochemical platform for precise regulation of horseradish peroxidase (HRP) enzymatic reaction immobilized on magnetic beads (MBs) and highly sensitive enzyme detection in both temporal and frequency domain. The ON/OFF switching characteristic ensures sensitive HRP detection with intrinsic noise rejection capability through time-domain signal decoupling, exhibiting a sensitivity of 0.223 uA·ng −1 ·mL −1 , a low detection limit (LOD) of 0.097 ng·mL −1 and a wide linear detection range of 0.1–200 ng·mL −1 . Meanwhile, the frequency-domain electrochemical analysis relies on an innovative periodic magnetic field modulation strategy, successfully isolates weak redox signals from background current by modulating the MBs-HRP periodically. The magnetically modulated redox cycling process generates periodic electrochemical oxidation and reduction signals for subsequent discrete Fourier transform analysis with enhanced detection performance. This specific approach broke the inherent limitations of electrochemical sensors, significantly decreased the LOD of electrochemical amperometric analysis, achieving an exceptional detection limit of 93.5 fg·mL −1 of HRP. This strategy is expected to provide a viable approach for the development of robust, simple, reversible, and highly selective magneto-controlled enzyme reaction systems, providing a universal platform for highly sensitive detection of ultra-low trace biomarkers.