*4.6. Optimization of the ICA*

The optimizations of the biochemical reagent dosages were essential for developing a sensitive and desirable ICA method for ZEN detection [32]. The key parameters were evaluated to improve the performance and sensitivity of the ICA, such as the dosage of K2CO<sup>3</sup> to adjust the pH value; BSA to block the nonspecific site at the surface of the GNPs; and the concentrations of ZEN-McAb, ZEN-antigen, and GAM-IgG to prepare the ICA strips. During the optimization process, the sensitivity of detection and clear judgment of the red color intensity by the naked eye should be focused on and selected.
