Electrochemical DNA biosensors based on thin gold films sputtered on capacitive nanoporous niobium oxide

Electrochemical DNA biosensors based on a thin gold film sputtered on anodic porous niobium oxide (Au@Nb₂O₅) are studied in detail here. We found that the novel DNA biosensor based on Au@Nb₂O₅ is superior to those based on the bulk gold electrode or niobium oxide electrode. For example, the novel method does not require any time-consuming cleaning step in order to obtain reproducible results. The adhesion of gold films on the substrate is very stable during electrochemical biosensing, when the thin gold films are deposited on anodically prepared nanoporous niobium oxide. In particular, the novel biosensor shows enhanced biosensing performance with a 2.4 times higher resolution and a three times higher sensitivity. The signal enhancement is in part attributed to capacitive interface between gold films and nanoporous niobium oxide, where charges are accumulated during the anodic and cathodic scanning, and is in part ascribed to the structural stability of DNA immobilized at the sputtered gold films. The method allows for the detection of single-base mismatch DNA as well as for the discrimination of mismatch positions.