Localization of multiple DNA sequences on nanopatterns.

DNA oligonucleotides of different sequences were patterned at the nanoscale. Areas of positive charge were generated by exposure of insulating substrates, spin-on hydrogen silsesquioxane or vapor-deposited SiO(2) on Si, with ionizing radiation sources used in electron beam and extreme ultraviolet lithography. Au nanoparticles (NPs) with a diameter of 15 nm, carrying covalently bound negatively charged single-stranded DNA oligonucleotides, were site specifically immobilized directly on the exposed regions and presented oligonucleotides for subsequent hybridization. Repeated exposure and deposition of NPs allowed for patterning multiple DNA sequences. Patterns with dimensions as small as 15 nm were fabricated using electron beam lithography. The use of DNA-functionalized NPs rather than just DNA facilitates metrology in scanning electron microscopy and improves the hybridization efficiency of the oligonucleotides on the surface.