Insights into the mechanism of Alzheimer’s β-amyloid aggregation as a function of concentration by using atomic force microscopy

The size and shape of Alzheimer’s β-amyloid structures, as well as the kinetics of their self-assembly, exhibits a very pronounced dependence on concentration and environment. In the present study, we are reporting the direct observation of Aβ oligomers and fibrils assemblies using atomic force microscopy imaging in fluid environment. These results demonstrate that in the Aβ preparations at lower concentrations, predominant are the globular, smaller oligomers, while for higher concentrations, globular oligomers co-exist with higher molecular weight fibrillar structures. At higher concentrations, the fibril formation is a dynamic and continuous process, yielding amyloid fibrils with multiple structures and diameters.