Characterization of oligomeric state of Aβ42, Aβ40 and Aβ42-Alexa555. (A) Atomic force microscopy (performed as described in Additonal file 3) images of Aβ42, Aβ40 and Aβ42-Alexa555 samples after 24 h incubation at 4 °C visualized on graphite. Sizes of field of view for left images are 4×4μm and for right images 1×1μm. Topographic profile for each Aβ sample is presented (measured globule is marked with blue line). All Aβ samples appear primarily as globular structures with following sizes: Aβ42 height 1.56 ± 0.3 nm, diameter at fwhm before deconvolution 75 ± 0.6 nm, diameter at fwhm after deconvolution 9.6 ± 0.1 nm; Aβ40 height 0.9 ± 0.1 nm, diameter at fwhm before deconvolution 43 ± 0.3 nm, diameter at fwhm after deconvolution 7.3 ± 0.1 nm; Aβ42-Alexa555 height 1.46 ± 0.2 nm, diameter at fwhm before deconvolution 68 ± 0.6 nm, diameter at fwhm after deconvolution 8.9 ± 0.1 nm. (B) Supernatant fractions of Aβ42, Aβ40 and Aβ42-Alexa555 preparations were separated on 15 % Acrylamide/Bis SDS gel and analyzed by Western blotting with anti-Aβ 6E10 monolconal antibodies. (PDF 375 kb)