Collagen fibrillogenesis in vitro: evidence for pre-nucleation and nucleation steps

Abstract The time dependence of turbidity increases as well as changes inmolecular weight associated with type I collagen self assembly were analysed in terms of classical nucleation and growth kinetics as well as in terms of the logistics equation. Kinetic studies suggest that the molecular weight increases during the lag and growth phases have different time dependencies. The time dependence of molecular weight and turbidity increases observed during the growth phase were found to be of the form e kt 2 consistent with classical nucleation and growth kinetics. The kinetics of the growth phase were found to be consistent with the nucleation of a ‘unit fibre’ that grew linearly. The kinetics of molecular weight changes during the turbidity lag phase were found to be inconsistent with classical nucleation and growth theory and therefore the lag phase was conceived of as a pre-nucleation step that involved multiple stages of assembly.