The conformations of both amyloid beta peptide 1-40 (Aβ1-40) in water, and amyloid beta peptide 1-42 (Aβ1-42) in DMSO (Dimethyl Sulfoxide) were investigated when they were adsorbed over nanogold colloids. We utilized fluorescein attached Aβ in order to probe an internal energy relaxation process, which directly reflects on both conformations of Aβ at the nano-scale interface and at the position of fluorescein with respect to Aβ sequences. For a given size of nano-gold, a neutral condition supported a moderate energy relaxation processes while drastic quenchings of fluorescence were observed at either an extreme acidic or basic condition. Unfolded conformations of peptide are expected at neutral regions, causing the fluorescein dye attached to the peptide to be well protected from interacting with other peptides. As expected, larger sizes of nano-gold (i.e., 60 nm and the above), caused more spacing between monomers, resulting in less interactions between adsorbed Aβ. The energy relaxation rate was significantly accelerated as the residual temperature was increased from 15 oC to 65oC. This was interpreted as an increase of non-radiative channels through the gold colloidal surfaces.

Investigation of peptide conformation through energy relaxation dynamics of fluorophore interacting with amyloid beta peptide at nanoscale interface

253rd National Meeting (2017)

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