presents SEM analysis of the PFKDOPA-coated silica beads, prior to and after nitrocefin incubation. Specifically, before the introduction of the nitrocefin solution, the PFKDOPA fibrils on the beads' surface were relatively homogeneous, with average diameters of 8 ± 2 nm. However, following 10 nitrocefin incubation cycles, the fibrils' thickness significantly increased, giving rise to 40 ± 10 nm diameters. Indeed, the thick fibrillar species apparent following incubation of the PFKDOPA-coated silica beads with nitrocefin, apparent both in the SEM image and fibril thickness bar diagram in Figure , echo the coiled fibril morphologies recorded by cryo-EM (i.e., Figure ).