Aggregation Study of Amyloid-β at the Air-Water Interface
Kim Lien T. Dinh, Dianlu Jiang, Feimeng Zhou
Department of Chemistry and Biochemistry
California State University, Los Angeles
5151 State University Drive
Los Angeles, CA 90032
Alzheimer’s disease (AD) is one of the most fatal neurodegenerative disorders in seniors. AD is characterized by the formation of insoluble plaques and fibrils aggregates of amyloid-β (Aβ) protein in the brain. Aβ belongs to a group of 39- to 43-residue-long peptide that undergoes misfolding from the soluble to the insoluble state with β-sheet content. Although extensive studies have been done to understand the morphologies of the aggregates on different substrates and in different solution environments, their mechanisms and structures are still not well understood. In this study, we utilize the Langmuir-Blodgett technique to study the assembly of Aβ. It is well known that Aβ is amphiphilic, thus allowing Aβ to freely aggregate at this interface with both hydrophilic and hydrophobic phases without any steric hindrance. In a Langmuir-Blodgett trough, Aβ is allowed to assemble at the air-water interface for different length of time, and then transferred onto hydrophobic and hydrophilic Silicon substrates as the film of Aβ is compressed at a constant pressure. Atomic Force Microscopy is then used to image the resulting samples. Small globular structures to large ones that are over 200 nm in height are detected. Attached along the edges of these large globular structures are short fibrils and a layer of tightly packed oligomers. By utilizing this interface to study the aggregation of Aβ, we are able to understand more about the formation of Aβ aggregates, and hopefully, extend the knowledge for the novel development of therapeutics.