Surface-induced aggregation of beta amyloid peptide by co-substituted alkanethiol monolayers supported on gold.

The primary pathological characteristic of Alzheimer's disease is the presence in the brain of self-assembled beta amyloid (Abeta) protein fibrils, consisting of 35-43 amino acid residues. The toxicity of the aggregated protein structures has previously been proposed to be related to the interaction of Abeta fibrils with neuronal membranes (phospholipid bilayers). Here, surfaces consisting of self-assembled alkanethiol monolayers with different end groups--supported on Au--are used to test the effect of surface chemistry on the structure and morphology of aggregates formed from an active fragment (Abeta10-35) of the Abeta peptide. The influence of monolayer nature (end group) on the aggregation of Abeta10-35 was examined using reflection-absorption infrared spectroscopy (RAIRS) and scanning force microscopy (SFM). Evaluation of the SFM and RAIRS data reveals the presence of Abeta10-35 protein on the various monolayer surfaces, with the surface protein possessing predominantly beta-sheet and random-coil conformations. Time-dependent studies of the extent of Abeta10-35 aggregation and deposition on the various surfaces and the effect of the monolayers on seeding of Abeta10-35 aggregates in solution are also discussed.