We studied the effect of salt and pH separately on the thermodynamic stability of the fibrils. We first prepared the fibrils in the absence or presence of salt (150 mM KCl) as well as neutral (pH 7.4) and acidic (pH 5) conditions. It has been reported that a distinct dominant polymorph is formed in each condition which is supported by the morphological differences observed in our AFM analysis of the fibrils (Figure ).