Fig. 7.

The fibers are permeable to 2.5 nm nanoparticles irrespective of their surface charge. Fibers were pulled out of a 0.4 mg/ml fibronectin solution in PBS and were treated with neutral (A), negatively (B), and positively (C) charged nanogold particles (2.5 nm) or with 10 nm negatively charged colloidal gold (D) or silver (E) nanoparticles for 1 h at room temperature prior to fixation. Alternatively, fibronectin was diluted in the colloidal solution of 10 nm negatively charged colloidal gold or silver nanoparticles to a final concentration of 0.4 mg/ml and fibers were pulled from these solutions in the presence of the nanoparticles (F). All samples were chemically fixed, ethanol dehydrated and embedded in Epon. 50 nm thick sections were observed by TEM. Scale bar: 200 nm for A-E and 500 nm for F.