Exploring of Cu-tannic acid laccase-mimicking nanozyme for effective degradation of aflatoxin B1

Abstract

Aflatoxin B₁ (AFB₁) is a notorious mycotoxin known for its mutagenic and carcinogenic properties, representing a significant hazard to food safety. This study synthesized copper-tannic acid (CuTA) nanosheets with laccase-like activity through a straightforward self-association process involving copper and tannic acid. The CuTA nanozyme demonstrated the ability to oxidize AFB₁, achieving a degradation rate of 95 % at an initial AFB₁ concentration of 2 μg mL⁻¹ at 37 °C within 24 h. UHPLC-HRMS analysis identified four degradation products catalyzed by CuTA nanozyme: M1 (C₁₆H₁₂O₅), M2 (C₁₇H₁₂O₇), M3 (C₁₇H₁₂O₇) and M4 (C₁₆H₁₄O₆). Three degradation pathways were proposed: 1) cleavage of the lactone ring in the coumarin moiety; 2) C3-hydroxylation leading to the formation of aflatoxin Q₁; 3) epoxidation of the unsaturated carbons on the terminal furan ring, followed by epoxide removal and loss of the methoxy group from the side chain of the benzene ring. The combined in vitro and in vivo toxicity evaluations demonstrated the significant detoxification capability of the CuTA nanozyme on AFB₁. Moreover, the application of CuTA nanozyme to degrade AFB₁ in peanut oil resulted in a removal rate of 78 % within 9 h. Collectively, these findings underscore the considerable potential of utilizing laccase-mimicking CuTA nanozyme for the detoxification of AFB₁.