Relaxation of flow birefringence can give a direct measure of the rotational diffusion of rod-like objects in solution. With a suitable model of the rotational diffusivity, a length distribution can be sought by fitting the decay curve. We have measured the flow birefringence decay from solutions of amyloid fibrils composed of b-lactoglobulin, and extracted a length distribution using the Doi-Edwards-Marrucci-Grizzuti theory of semidilute rotational diffusion. The concentration scaling of the results show that the fibrils diffuse as free rods: they cannot be significantly branched, sticky or break up under dilution. The length distribution obtained shows a single broad peak, consistent with measurements of the fibrils by electron microscopy. This comparison, and combination of the experiment with an assay to find the total concentration of fibrils, allows calibration of the length scale and concentration scale of the length distribution. It is our hope that this method can be used for following the growth kinetics of amyloid fibrils in vitro, and for studying the length distribution of rod-like systems in general.
|Publication status||Published - 2006|
|Event||Symposium BioNanotechnology - NanoAssembly - |
Duration: 11 May 2006 → …
|Conference||Symposium BioNanotechnology - NanoAssembly|
|Period||11/05/06 → …|