Figure 5.

Transmission electron microscopy (TEM) images of nanostructures revealed at different pH and ionic strength. (A) 20 mM Acetate buffer, pH 4.5, NaCl 150 mM. The TEM micrograph shows nearly spherical nanoparticles with a diameter size variability that has been estimated to be 60±15 nm. The bar at the bottom of the picture corresponds to 200 nm. (B) Zoom of a single nanoparticle of (A). The bar at the bottom of the picture corresponds to 50 nm. (C) 20 mM 2-(N-morpholino)ethanesulfonic acid buffer, pH 6, NaCl 150 mM. The TEM micrograph shows long rods with a lateral dimension of 40–100 nm and a length in the order of a few millimeters. The bar at the bottom of the picture corresponds to 500 nm. (D) 20 mM Tris HCl in the presence of 150 mM NaCl and 200 mM CaCl₂. The TEM image reveals the presence of small spots that are compatible with the expected presence of VP6 trimers.⁵ The bar at the bottom of the picture corresponds to 200 nm.