Supplementary data
Fig. 1: Darkfield image and AFM image of 80 nm gold nanoparticles. Nanoparticles are immobilized
on a glass substrate, which was silanized with 3-aminopropyltriethoxysilane (APTES). AFM was used
before DNA hybridization experiments to distinguish between single nanoparticles and nanoparticle
aggregates.
Fig. 2: SEM images of 80 nm gold nanoparticles on a glass substrate. Prior to SEM measurement, the
whole substrate was coated by a thin gold layer for better conductivity. Due to the coating process
and limitations of the scanning electron microscope (quality loss by poor conductivity), the detection
of small 20 nm nanoparticles, attached to the larger 80 nm gold nanoparticles, was not
representable.