Microlithographic patterning of oligonucleotides: Toward fabrication of multilevel DNA based devices

A strategy for achieving geometrical patterning of DNA is described. The approach comprises patterning of oligonucleotides on a glycidyl oxypropyl trimethoxy silane modified Si wafer by spin casting a photoresist mixture consisting of a photoacid generator and a reactive blocking group and exposing through a photomask. Highly specific micrometer-sized DNA geometrical patterns were obtained, activity (multiple hybridization-dehybridization cycles with no loss of activity) and specificity of which were assessed using labeled complementary oligonucleotides. To further use such an approach toward integration, a novel two-stage strategy has been demonstrated, where the first stage lithography was employed to pattern electrodes and a second stage alignment/exposure was employed to define oligonucleotides between the electrodes.