Specific and efficient adsorption of phosphorothioated DNA on Au-based surfaces and electrodes

Efficient attachment of DNA to metal surfaces or electrodes is essential for charge-transport measurements, scanning tunneling microscopy, and for devices and sensors. To optimize DNA deposition on Au-based surfaces and electrodes, we synthesized DNA with phosphorothioate (PT) groups attached to the G strand of poly(deoxyguanine)-poly(deoxycytosine) [poly(dG)-poly(dC)]. This procedure strongly improves the DNA anchoring to Au-based surfaces by sulfur-gold interaction. Much higher molecular surface density on Au substrates was observed for PT poly(dG)-poly(dC) compared to "bare" molecules. Deposition of PT poly(dG)-poly(dC) on Au-based electrodes, followed by thorough washing, showed that they specifically attach to the electrodes and are not spread on the surrounding Si O2 surface.