IAPP and type 2 diabetes mellitus: αS, an anionic neuronal protein (pI: 4.67)35 implicated in the pathology of PD36,37, islet amyloid polypeptide (IAPP), a cationic human pancreatic polypeptide (pI: 8.8)38 implicated in the pathology of type 2 diabetes (T2D)39, and FapC (zeta potential of FapC fibrils: −36 mV)40, a protein constituent of the Pseudomonas aeruginosa functional amyloid41, were used in our study in addition to Aβ (Fig. 1a).