Orientation-defined alignment and immobilization of DNA between specific surfaces

DNA-based single-molecule studies, nanoelectronics and nanocargos require a precise placement of DNA in an orientation-defined manner. Until now, there is a lack of orientation-defined alignment and immobilization of DNA over distances smaller than several micrometers. However, this can be realized by designing bifunctionalized DNA with thiol at one end and (3-aminopropyl) triethoxy silane at the other end, which specifically binds to a gold and SiO2 layer after and during alignment, respectively. The electrode assembly consists of platinum as the electrode material for applying the AC voltage and islands of gold and silicon dioxide fabricated at a distance of about 500-800 nm by electron-beam lithography. The orientation-defined alignment and covalent binding of pUC19 DNA to specific surfaces are carried out in frequency ranges of 50 Hz-1 kHz and 100 kHz-1 MHz and observed after metallization of DNA by palladium ions by field emission scanning electron microscopy (FESEM). The bifunctionalized 890 nm long DNA was effectively aligned and immobilized between a gap of 500 to 600 nm width.