*2.1. Identification of the Gold Nanoparticles 2.1. Identification of the Gold Nanoparticles*

The image of the transmission electron micrograph showed that the prepared colloidal gold nanoparticles (GNPs) were about 17 nm and the particles exhibited a uniform distribution (Figure 2A). The ultraviolet–visible spectra (UV/vis) for the GNPs solution had a smooth protruding peak at 518 nm. Qualitative differences were found between the UV/vis spectra of the ZEN‐monoclonal antibody (McAb)‐GNP probes and GNPs (Figure 2B). The ZEN‐McAb‐GNP probes showed a smooth protruding peak at 527 nm, indicating that the GNPs had been successfully coupled in ZEN‐McAb The image of the transmission electron micrograph showed that the prepared colloidal gold nanoparticles (GNPs) were about 17 nm and the particles exhibited a uniform distribution (Figure 2A). The ultraviolet–visible spectra (UV/vis) for the GNPs solution had a smooth protruding peak at 518 nm. Qualitative differences were found between the UV/vis spectra of the ZEN-monoclonal antibody (McAb)-GNP probes and GNPs (Figure 2B). The ZEN-McAb-GNP probes showed a smooth protruding peak at 527 nm, indicating that the GNPs had been successfully coupled in ZEN-McAb to produce

probes. Further studies of the ICA evaluation and application also demonstrated the availability and excellent performance of the prepared GNPs. *Toxins* **2020**, *x*, x FOR PEER REVIEW 3 of 12

**Figure 2.** The transmission electron micrograph image for the gold nanoparticles (GNPs) (**A**) and the UV/vis spectra for the GNPs and zearalenone (ZEN)‐monoclonal antibody (McAb)‐GNP probes (**B**). **Figure 2.** The transmission electron micrograph image for the gold nanoparticles (GNPs) (**A**) and the UV/vis spectra for the GNPs and zearalenone (ZEN)-monoclonal antibody (McAb)-GNP probes (**B**).
