Fig. 4

Scanning transmission electron microscopy (STEM) images of the same sample shown in Fig. 3a and c, after an additional fixation step with glutaraldehyde, and coating with multilayer graphene, keeping the cells in hydrated state inside the electron microscope. a Low magnification (800 x) overview STEM image of the same region as shown in Fig. 3c used to navigation to the regions of interest. b Low magnification (4000 x) overview STEM image of the boxed cell in a, the same as shown in Fig. 3c. The multilayer graphene sheet, covering the whole sample, was invisible, except for some faint, bright, linear structures, representing fine folds in the graphene (see arrows). c STEM image (120,000 x magnification) recorded at the boxed region in B revealing the abundance of labelled HER2 on the cancer cell. The electron-dense QD labels were automatically detected and outlined in yellow to enhance their visibility. d The pair correlation function g(r) measuring the probability of a certain inter-label distance r calculated for the labels shown in c. The peak at ~ 20 nm indicates the presence of HER2 homodimers. Scale bars, in a: 50 μm, in b: 10 μm, and in c: 500 nm