Multiple Enzyme-Mimicking CuMOF-Driven Self-Cascading Antioxidant Reaction for Synergistic Electrochemiluminescence Modulation in Ultrasensitive Biosensing

Developing nanozyme-based free radical scavenging is a promising signal modulation approach for ECL sensing. Nevertheless, the relatively low antioxidant activity and inherent pro-oxidant activity of numerous nanozymes have significantly hindered the development of this strategy. Here a biofunctional copper-based metal–organic framework (CuMOF) with multiple enzyme-mimicking activities was employed for the modulation of the ECL immunosensor, guided by the self-cascade antioxidant reaction. The inherent SOD, CAT, and the capacity to eliminate ·OH endow CuMOF with powerful synergistic antioxidant effects while little pro-oxidant activities were displayed, enabling efficient scavenging of the O₂^·– produced during the electrochemical oxidation of H₂O₂. Subsequently, the nanoconfinement effect of the layered double hydroxide was introduced to ensure a steady ECL signal. The suggested ECL immunosensor, using aflatoxin B₁ as a proof-of-concept target, demonstrated a detection range spanning from 0.001 pg/mL to 10 ng/mL, with the detection limit calculated to be 0.18 fg/mL. This exceptional achievement greatly broadens the range of possible uses for nanozyme-based radical scavenging modulated ECL analysis.