Figure 9.

Gopal et al. nanoinjected cells with different cargoes to explore which uptake mechanisms were stimulated by interfacing with porous silicon nanoneedles. (A) Percentage of positive cells for different mechanism-specific cargoes. Transferrin is a clathrin-mediated endocytosis cargo, cholera toxin B-subunit (CTxB) is a caveolae-specific cargo, and dextran (Dex, tested in different molecular weights) is a micropinocytosis-specific cargo. After confirming that surface area did not affect loading efficacy, they noted that all cargoes were more successfully internalized in cells on nanoneedles compared to flat silicon wafers. (B) Focused-ion-beam scanning-electron-microscopy micrograph of nanoneedle interacting with cell membrane (scale bars 100 nm), showing two different types of vesicular structure (clathrin pits and caveolae). (C) 3D reconstruction of vesicular structures on nanoneedle (red) and non-nanoneedle (blue) regions, nanoneedles shown in green. Reproduced under the terms of CC BY license.^[84] Copyright 2019, The Authors.