AFM imaging of functionalized carbon nanotubes on biological membranes

Abstract

Multifunctional carbon nanotubes are promising for biomedical applications as theirnano-size, together with their physical stability, gives access into the cell and variouscellular compartments including the nucleus. However, the direct and label-free detection ofcarbon nanotube uptake into cells is a challenging task. The atomic force microscope(AFM) is capable of resolving details of cellular surfaces at the nanometer scale and thusallows following of the docking of carbon nanotubes to biological membranes. Herewe present topographical AFM images of non-covalently functionalized singlewalled (SWNT) and double walled carbon nanotubes (DWNT) immobilized ondifferent biological membranes, such as plasma membranes and nuclear envelopes, aswell as on a monolayer of avidin molecules. We were able to visualize DWNT onthe nuclear membrane while at the same time resolving individual nuclear porecomplexes. Furthermore, we succeeded in localizing individual SWNT at the border ofincubated cells and in identifying bundles of DWNT on cell surfaces by AFM imaging.