The detailed synthesis of hapten-BSA immunogens, hapten-KLH immunogens, and hapten-OVA coating antigens is provided in the Supplementary Information. The hapten-BSA conjugates were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS, Bruker, Bremen, Germany). Ten eight-week-old female BALB/c mice per immunogen were immunized according to our previously described procedure. Briefly, the first injection was 100 µg of the immunogen emulsified with CFA, followed by two subcutaneous injections of 100 µg of the immunogen with IFA. From the second immunization, mice antisera were collected on the 7th day after each immunization to monitor antibody titer and affinity by noncompetitive ELISA (ncELISA) and competitive indirect ELISA (ciELISA), as described in the Supplementary Information. After the third immunization, the mice exhibiting the highest affinity from each group were killed for subsequent cell fusion.