Electrical Stimulation-Boosted Catalytic Activity of Fe/Ce-Tpy Nanozyme: Mechanistic Insights and Sensitive SERS...

Traditional nanozymes suffer from inefficient catalytic kinetics and slow signal response, limiting their use in rapid-response sensors for real-sample analysis. Herein, we developed an external electrical stimulation regulation strategy that directly drives valence cycling in bimetallic MOF nanozymes. This approach reduces the activation energy and promotes the generation of reactive oxygen species, thereby synergistically enhancing the peroxidase-like activity of the MOF nanozyme system, which also shortens the reaction time. By overcoming the inherent electron-transfer rate limitation in conventional enzyme catalysis, it enables rapid cycling of active valence states. Consequently, the application of an external electrical stimulation enables the rapid oxidation of leuco-malachite green to surface-enhanced Raman scattering (SERS)-active malachite green (MG) within 45 s, drastically shortening the reaction time from 45 min and enabling rapid sensor response. The accelerated kinetics minimize intermediate dissipation and maximize analyte utilization, facilitating rapid and pronounced accumulation of the Raman reporter MG for highly sensitive detection. Based on this mechanism, a target-triggered hybridization-assisted SERS sensor was constructed for alternariol toxin detection, achieving a wide linear range of 0.2-100 ng/mL (R2 = 0.9996) and a low limit of detection of 0.074 ng/mL. The sensor demonstrates high selectivity, stability, and applicability in complex food matrices. This work provides an effective acceleration strategy to overcome the kinetic limitations of nanozyme-based sensors, enabling rapid and sensitive detection of trace mycotoxins for food safety monitoring.