The formation of oligomers of amyloid beta (Aβ) is regarded as a critical onset stage of Alzheimer's disease. While oligomers are produced as a heterogeneous ensemble of different types of oligomeric forms (e.g., dimer, trimer, tertramer, etc.), the presence of a nanoscale surface may selectively produce a specific oligomeric form. It has been hypothesized that the order of the oligomer is considered to increase proportionally to the size of nanoscale surface available. For example, dimer, trimer, and tetramer units are selectively produced as the gold nanoparticle increased in size from 10 nm to 100 nm. In order to establish a new methodology to probe a specific oligomeric form, we investigated the fluorescence dynamics of a fluorescein-attached Aβ1-40 monomer (FAβ1-40). The fluorescence decay times of FAβ1-40 on various sizes of gold nanoparticles, ranging between 10 nm and 100 nm in diameter, were observed as the folded and unfolded conformations of the monomer formed. The folding and unfolding conformations were induced by altering the pH between 10 and 4, respectively. Faster dynamics were observed in acidic environments as well as in the presence of the larger gold colloids implying that larger oligomer units provide a higher density for nonradiative channels.

Probing nanosize-dependent oligomerization by using fluorescence dynamics of fluorescein amyloid beta 1-40 peptides

249th National Meeting (2015)

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