Figure 1.

Growth of epithelial cells on a gold nanoparticle-decorated substrate. (A) Optical dark field microscopy detects light scattered by the sample. Gold nanoparticles appear as bright spots with colors corresponding to the plasmon frequency of the particle. The dense inner cell region with the strongly scattering cytoplasm appears bright white. The spread cell membrane is thin and translucent allowing observation of the nanoparticles underneath. (B) Magnified view of the nanoparticles covered with the membrane as marked in (A). (C) Scanning electron microscopy image of gold nanoparticles underneath the thin cell membrane. The membrane tightly covers the nanoparticles. (D) Optical dark field microscopy image of an area where the cell membrane has retracted. There are no irregularities or voids in the nanoparticle pattern, indicating that no nanoparticles were displaced. After retraction, a filamentous residue remains attached to the nanorod-decorated substrate. Since these filaments occur in the control samples of bare substrates as well, this behavior does not necessarily indicate an interaction of cell membrane and nanorods.