DNA monolayer on gold substrates characterized by nanoparticle labeling and scanning force microscopy

Monolayers of single-stranded DNA on gold substrates were studied by scanni ng force microscopy. Complementary DNA probes labeled by gold nanoparticles were applied for contrast enhancement. Substrate regions modified with DNA could be visualized in a highly specific manner. The influence of the solu tion concentration on the surface density of adsorbed nanoparticles could b e visualized. Because individual label particles can be easily detected, th is labeling technique opens the way for characterization of DNA monolayers with a lateral resolution in the nanometer range.