*2.13. Scanning Electron Microscopy (SEM)*

Agar disks of *A. flavus* had been inserted into sterile cellophane films and transferred to PDA mixed with 180 ppm of Cu-Chit/NCs hydrogel in Petri dishes, with one plugin keeping in the middle of the plate, and 3 replicates were used for every strain. The Petri dishes were incubated at 28 ◦C for 7 days. Cellophane coated with *A. flavus* was transferred and stuck in 2% (*w*/*v*) glutaraldehyde at 4 ◦C for 12 h in 0.1 M phosphate buffer (PB; pH 7.0). Aspergillus specimens will be put in the desiccator before further use. Upon drying, the samples prepared are assembled into the Poutron SEM coating system using standard double-sided adhesives with <sup>1</sup> 2 inch SEM nozzles and with a gold-palladium gold coating (60 s, 1.8 mA, 2.4 kV). All samples were tested with JEOL JXA-480 SEM (JEOL, Tokyo, Japan) at the National Research Center in Giza, Egypt.
