Self-assembly of amyloid beta peptide (A�) is a crucial step of the fibrillogenesis, which is considered as an onset hallmark mechanism of Alzheimer's disease. We have investigated an oligomer formation of A�1-40 monomers over the nanogold colloidal surface as an external pH was changed between pH 4 and pH 10. Under pH 4, unfolded A�1-40 monomer constructed a dimer or trimer based oligomeric form while  a conformation of A� constructed under pH 10 consists of a folded monomer avoiding the networking with residual colloidal particles. When A� was attached to both silver and gold surface, silver surface was found to restrict the channel of unfolding process. There was specific size/temperature dependence in a reversible self-assembly. Over 20 nm gold colloid, a reversible assembly process of A�1-40 monomer was observed in the temperature range of 5 oC and up to 65 oC. When 30 nm or 40 nm gold colloids were used a reversible self-assembly was observed below 5 oC. Most probable oligomer form constructed over 20 nm gold colloidal surface is dimer based unit and that over 30 or 40 nm gold colloidal surface is concluded to be a trimer based unit. However, self-assembly was not successfully reproduced under the rest of conditions. A significant enhancement of a reversible self-assembly was achieved when a surface environment of gold colloid was functionalized with dibenzyloxy disulfide. The highest effect was obtained when electron donating group was used in para-substitution.

Controlling a reversible self-assembly path of amyloid beta peptide by nanoscale metal surface

248th National Meeting (2014)

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