The Effect of Ultrasonication on the Fibrillar/ Oligomeric Structures of Aβ 1-42 at Different Concentrations

The number of disease states linked the aberrant regular protein conformations to oligomers and amyloid fibrils. Amyloid beta 1–42 (Aβ 1−42 ) peptide is very hydrophobic and quickly forms the β-rich structure and fibrillar protein aggregates in some solutions and buffer conditions. Ultrasonication pulses can disrupt amyloid fibrils to smaller fragments and produce Aβ 1−42 peptides of different sizes and oligomers. Herein, we investigated the effects of buffer and ultrasonication on Aβ 1−42 structure at low and high concentrations. The electrophoresis and Western blot results showed that Aβ 1−42 fibrils were disrupted into different sizes after ultrasonication. The transmission electron microscopy results indicated Aβ 1−42 at low concentration (25 µM) in Ham’s/F12 phenol red-free culture medium formed short-size fragments and oligomers. In comparison, Aβ 1−42 at higher concentration (100 µM) formed fibrils that break down into smaller fragments after ultrasonication. However, after regrowth, it formed mature fibrils again. The cell cytotoxicity results indicated more toxicity of Aβ 1−42 oligomers formed at low concentration (25 µM) against PC12 cells than other forms. In conclusion, by applying ultrasonication pulses and controlling peptide concentration and buffer condition, we can rich Aβ 1−42 aggregates with a particular size and molecular structure.