Figure 4: Immunofluorescence staining of cellular vimentin fibres with Qdot705.

(a) Vimentin fibres in REF cells immunostained with Qdot705 and imaged with the excitation (Exc.) plus the STED laser beam. Scale bar, 1 μm. (b) QDs imaged with the STED laser beam only. Images in a and b were acquired by line-wise multiplexing. (c) Subtraction of the STED laser beam-only image (b) from the excitation plus the STED laser beam image (a) (3 × 3 median filter). (d) Confocal image of the same region. Note that the lookup tables were adjusted for better visualization. Images in e and f are insets from white squares in c and d, respectively. Scale bar, 1 μm. (g) Intensity profile averaged 200 nm along a single vimentin fiber indicated in a and b. (h) Profile as in g for the subtracted image (c) and the confocal image (d). (i) Line profile of the position indicated by arrow heads in e and f. The two fibres, resolved to a distance of 140 nm in the super-resolved image, appear as a single blurred object in the confocal reference image.