Fig. 2: Cryo-EM images of the PS-COOH NPs obtained with a direct electron detector and phase plate.

a Original NPs without corona; b NPs with corona; c, d higher magnification of the NPs showing the distribution of biomolecules and their association with the surface of the NPs. Nonspecific proteins accumulate between the NPs as large clusters (black arrows). The black dots in the images are 10 nm gold fiducial markers.