DNA probes on chip surfaces studied by scanning force microscopy using specific binding of colloidal gold.

Single-stranded DNA was covalently bound on chip surfaces using two different silanization procedures. The resulting surfaces were characterized by fluorescence and scanning force microscopy using sequence-complementary DNA molecules with labels. Colloidal gold (30 nm) was used as the topographic label. Scanning force microscopy revealed the individual labels on the surface and their distribution. Steps of silane layers or DNA-modified surfaces prepared using an elastomeric mask provided internal controls for comparison of modified with unmodified surfaces.