Preparation of highly sensitive monoclonal antibody against aflatoxin B_1 and its application in rapid detection of contamination in Ziziphi Spinosae Semen

Abstract

A highly sensitive monoclonal antibody against aflatoxin B_1(AFB_1) was prepared and an indirect competition enzyme-linked immunosorbent assay(ic-ELISA) was established based on the antibody which was used for high-throughput and rapid screening of AFB_1 contamination in Chinese herbal medicines to ensure the safety of medication. In this study, the structure of AFB_1 was modified by improved oxime method, and the carrier protein was coupled by EDC-NHS method to obtain the complete antigen of AFB_1, which was more convenient and environmental friendly. The Balb/c female mice were immunized using increasing the immunization dose and various ways of injection, and finally the AFB_1 monoclonal antibody was prepared. The AFB_1 monoclonal antibody belongs to IgG_(2 b) immunoglobulin by identifying its immunological characteristics, and its sensitivity(IC_(50)) can reach 0.15 μg·L~(-1), and the affi-nity is 2.81×10~8 L·mol~(-1). The cross-reaction rates of AFB_2, AFG_1, and AFG_2 were 35.07%, 8.75%, and 1.15%, respectively, and there was almost no cross-reactivity with other mycotoxins. Based on the high sensitivity and specificity of the antibody, an ic-ELISA method was established and applied to the determination of AFB_1 contamination in Ziziphi Spinosae Semen. According to the matrix matching standard curve, the linear concentration range for AFB_1 was 0.05-0.58 μg·L~(-1)(R~2=0.992), the recoveries were 88.00%-119.0%, and the detection limit was 1.69 μg·kg~(-1). The AFB_1 in 33 batches of Ziziphi Spinosae Semen samples was determined by ic-ELISA, and the contamination level was 3.62-206.58 μg·kg~(-1). The linear correlation coefficient between the detection results of ic-ELISA and UHPLC-MS/MS was 0.996, and there were no false positive and false negative cases. It indicates that the established ic-ELISA is accurate and reliable, and could provide a simple and effective technique for fast screening of AFB_1 contamination in Ziziphi Spinosae Semen, and also could be considered as the reference for the detection and monitoring of AFB_1 contamination in other Chinese herbal medicines.