Fig. 5: Tomogram reconstruction of nanopillar-induced envelope penetration in K. pneumoniae.

A tilt series was acquired of K. pneumoniae under bright-field TEM a, where multiple nanopillars appeared to be penetrating the envelope (1–6). Analysis of nanopillar tip coordinates in x, y and z revealed that nanopillars 1–4 and 6 had penetrated the envelope, while nanopillar 5 was only deforming the cell. A 3D reconstruction of the tomogram revealed all nanopillars had penetrated the bacterial envelope by at least 100 nm b. The dark bands seen within nanopillars are bend contours; these spatial contrasts arise from local bending or deformation of nanopillars. Electron tomography was performed on five K. pneumoniae cells interacting with TiO2 nanopillars, these were acquired in four tilt series.