Aggregate Size Dependence of Amyloid Adsorption onto Charged Interfaces

Amyloid aggregates
are associated with a range of human neurodegenerative
disorders, and it has been shown that neurotoxicity is dependent on
aggregate size. Combining molecular simulation with analytical theory,
a predictive model is proposed for the adsorption of amyloid aggregates
onto oppositely charged surfaces, where the interaction is governed
by an interplay between electrostatic attraction and entropic repulsion.
Predictions are experimentally validated against quartz crystal microbalance–dissipation
experiments of amyloid beta peptides and fragmented fibrils in the
presence of a supported lipid bilayer. Assuming amyloids as rigid,
elongated particles, we observe nonmonotonic trends for the extent
of adsorption with respect to aggregate size and preferential adsorption
of smaller aggregates over larger ones. Our findings describe a general
phenomenon with implications for stiff polyions and rodlike particles
that are electrostatically attracted to a surface.