Tip-Enhanced Raman Spectroscopy Of A Beta(1-42) Fibrils

Using tip-enhanced Raman spectroscopy (TERS) imaging with a lateral optical resolution of similar to 16 nm, the heterogeneity of A beta(1-42) fibrils implicated in Alzheimer's disease is investigated. The amount and spatial distribution of TERS bands assigned to aromatic amino acid residues (histidine, tyrosine and phenylalanine) and to parallel beta-sheet and random coil secondary structures suggest that both the surface and core of A beta(1-42) fibrils are probed, confirm the twisted nature of the fibrils and reveal the presence of several beta-sheet and disordered fibril regions with different hydrophilicity. This study completes and bears out literature TERS data on A beta(1-42) amyloid fibrils.