To further explain the scientific basis of antibody-analyte-antibody recognition utilized by the sandwich immunoassay for small molecules in this study, structural studies on mAb pairs 7A3-17B3, 7A3-10A9, and 7A3-7F2 in the complex with typical model analytes were conducted by molecular docking and molecular dynamics after antibody sequencing (Supplementary Table ). Unlike the docking of the antibodyantigen binary complex, there are few protocols for the construction of antibodyanalyte-antibody ternary complexes. According to prior experiences in proteolysistargeting chimeras (PROTAC), we first studied the antibody-analyte-antibody ternary complex in sandwich immunoassays for small molecules (Supplementary Fig. ). Briefly, taking 7A3-MN7-17B3 as an example, the starting orientations of the 7A3-MEL and 17B3-NIA binding moieties should be first provided to form an initial configuration. After 7A3 and 17B3 protein-protein docking to determine the relative position of the two mAbs, the 7A3-MEL and 17B3-NIA binding moieties were superimposed onto their respective mAbs in the 7A3-17B3 complex to form a shared binding cavity. Finally, after removing the MEL and NIA, MN7 was placed in the shared binding cavity, and molecular dynamics was carried out to obtain the stable conformation of 7A3-MN7-17B3.