TEM-images of amelogenin rH174 at different times of incubation; top row (a–c) rH174 was dissolved in aqueous suspensions at pH 2–3, subsequently pH was raised 4.5 using KOH and Tris-buffer. The characteristic 20 nm nanosphere of amelogenin was observed at all time points between 1 to 14 days of incubation, t = 24 h (a); occasionally nanosphere aggregated into short strings, t = 48 h (b), and t = 7 days (c). When aqueous amelogenin suspensions were mixed at pH 2–3 with a non-polar solvent (octanol/ethyl acetate) and subsequently pH was raised to 4.5, ribbon-like nano-structures appeared as early as 24 hours (d). Ribbons grew in length over time and arranged themselves in a parallel manner, t = 7 days (e); ribbons reached several micrometer in length and formed well aligned bundles of nanoribbons, t= 14 days (f).