Fig. 3: SR-SICM imaging of amyloid peptide fibers.
A Experimental SICM image of a sample containing peptide fibrils. A pipette with an inner radius of 45 nm was used and the top-left inserts show the pipette tip schematic and calculated point-spread function, respectively. Four areas of interest are indicated, (α), (β), (γ) and (λ). These areas include a fibril particle (B), fibril (C), two parallel fibrils (D) and a branching fibril (E). For (B–D), subfigures (I), (II) and (III) are SICM, SR-SICM and line-profiles, respectively. For E, subfigures (I), (II) are the SICM and SR-SICM images, while (III), (IV) and (V) are line profiles of λ1, λ2, and λ3. The line-profiles of γ and λ1 in (D, E) are reproduced theoretically by simulating line-profiles of two adjacent cylinders separated by a distance of 4.5 ri (F) and 3 ri (G). Graphical maps are produced exploring the imaging capabilities of (H) regular and SR-SICM (I) when imaging two adjacent cylinders with different radius and center-to-center distances. The colored areas correspond to geometries where imaged cylinders can be resolved according to the Rayleigh criterion while the striped areas correspond to geometries, which cannot be resolved.
