A novel biosensor for silver(i) ion detection based on nanoporous gold and duplex-like DNA scaffolds with anionic intercalator

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 anthraquinone-2,6-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 × 10⁻¹⁰ M to 1 × 10⁻⁶ M, and the lower detection limit of the biosensor for Ag⁺ is 4.8 × 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.