Abstract
This study demonstrates a novel biosensor for silver(I) ion detection based on nanoporous gold (NPG) and duplex-like DNA scaffolds with anionic intercalator. The hairpin structure was formed initially through hybridization with the unlabeled probe (S1 + S2 + S3). In the presence of Ag+, the structure of immobilized DNA changed to duplex-like structure, and formed a C-Ag+-C complex at electrode surface. The response current of the modified electrode after immersing in the disodium anthraquinone2,6- disulfonate (AQDS) as the signal agent was changed. And an increased current was obtained, corresponding to Ag+ concentration. NPG provided faster electron transfer and an excellent platform for DNA immobilization. Under optimal conditions, silver(I) ion could be detected in the range from 1 x 10(-10) M to 1 x 10(-6) M, and the lower detection limit of the biosensor for Ag+ is 4.8 x 10(-11) M with good specificity. The results showed that this novel approach provided a reliable method for the quantification of Ag+ with sensitivity and specificity, which was potential for practical applications.