To further demonstrate that monomer binding can be observed during fibril growth, we have measured amyloid elongation of α-synuclein at pH 5.5, where the protein is close to its isoelectric point and surface binding of monomer can be expected, as secondary nucleation is strongly enhanced under these conditions . While no clear bi-phasic behavior is evident in the raw data, the DF-plot reveals a low ∆D to ∆F phase in the early time steps of the pH 5.5 growth phase, which becomes exacerbated after Proteinase K treatment (Fig. ). The time-resolved DF-plots show a lower dissipation response during the first 200 seconds of the incubation period before the DF-response converges to the signature of amyloid elongation. Compared to injections at pH 7.4, where the elongation signature is achieved within 1 minute of incubation, it is evident that some non-fibrillar mass deposition can be identified as a perturbation in the DF-plots(Fig. ).