Abstract
In this study, self-assembled monolayer (SAM) method was employed to fabricate monolayer of β-amyloid peptides Aβ42 on gold substrate with a bolaamphiphile named thiol (MHA). Firstly, the samples of gold substrate (blank control), the MHA-modified substrate and the Aβ42-modified substrate were detected by X-ray photoelectron spectroscopy (XPS) to track the self-assembly process. The spectra of binding energy measured from these three sample surfaces could be well fitted with the corresponding monolayer’s composition, which means Aβ42 monolayer is well formed. Aggregation behaviors of Aβ42 in the absence and presence of metallic ions (Zn2+、Ca2+、Al3+) were then monitored by atomic force microscopy (AFM) and surface-enhanced Raman Scattering (SERS), respectively. The recorded surface morphology of different experimental groups obtained by AFM showed markedly different nanostructures, indicating occurrence of aggregation behaviors of Aβ42. In solutions with added metal ions, the increased size of surface structures was observed, which suggest the presence of metal cations promotes aggregation behavior between Aβ42 molecules. Furtherly, the interaction between Aβ42 and metal cations was investigated by SERS. The results demonstrate that the Raman strength of Aβ42 changes after the metal cation treatment. Taken together, the combined AFM imaging and Raman analyses show that the three kinds of metallic ions promote the process of Aβ42 aggregation.
Evaluating Effect of Metallic Ions on Aggregation Behavior of Amyloid Aβ42 by AFM Imaging and SERS
