Two birds with one stone: A hollow MnO2nanozyme immunosensor for simultaneous accurate detection and highly efficient removal of aflatoxin B1in peanuts.

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.