Experimental esimation of diffusion coefficient versus time. The lateral protofibrils association process monitored by dynamic light scattering (DLS). Isolated protofibrils (3 or 5 µ M) of Aβ 42 buffered in 20 mM Tris-HCl, pH 8.0 was allowed to associate by the addition of 150 mM NaCl at room temperature. The reaction was monitored using DLS instrument for the shown period of time. The control sample was 5 µ M protofibril sample in the absence of NaCl.