Two birds with one stone: A hollow MnO₂nanozyme immunosensor for simultaneous accurate detection and highly efficient...

Aflatoxin B₁(AFB₁), a highly toxic mycotoxin, is widely prevalent in mold-contaminated grain crops and poses serious health risks to humans and animals, even at trace levels. Owing to its high toxicity and stable chemical structure, AFB₁ is difficult to specifically detect and remove using conventional methods, leading to substantial annual losses of grain crops due to contamination. Therefore, there is an urgent need to develop sensitive and on-site strategies for the early warning and effective decontamination of AFB₁. To address this challenge, we synthesized a dual-functional hollow mesoporous manganese dioxide (H-mMnO₂) nanozyme with remarkable oxidase-mimicking catalytic activity and high adsorption performance for the detection and removal of AFB₁ in peanuts. Specifically, an innovative antibody-grafted indirect competitive enzyme-linked immunosorbent assay (icELISA) strategy based on the H-mMnO₂ nanozyme was elaborately designed to enable on-site and sensitive quantification of AFB₁. Benefiting from its outstanding oxidase-mimicking catalytic properties, the H-mMnO₂ nanozyme conjugated with a specific recognition antibody generates a colorimetric signal without requiring hydrogen peroxide (H₂O₂), facilitating visual, specific, and quantitative analysis of AFB₁. The proposed method achieves reliable and ultrasensitive determination of AFB₁ with a limit of detection (LOD) of 0.00562 ng mL^-1. More importantly, the engineered H-mMnO₂ nanozyme enables nontoxic and highly efficient removal of foodborne AFB₁, attributed to its hollow mesoporous structure. Furthermore, it can catalyze the degradation of AFB₁, disrupting the toxin's structure and achieving a removal efficiency of 91.56% within 2 h. Collectively, these results demonstrate the great potential of the H-mMnO₂ nanozyme as a "two birds with one stone" nanoplatform for simultaneous on-site ultrasensitive detection and highly efficient decontamination of AFB₁ in grains and other food products.