Surface plasmon resonance detection of silver ions and cysteine using DNA intercalator-based amplification

• DOI: 10.1007/s00216-012-5720-5
• Publication Date: 2012-01-27T07:55:24Z
• Authors: Chia-Chen Chang; Shenhsiung Lin; Shih-Chung Wei; Yu Chu-Su; Chii-Wann Lin
• Keywords: Ions; Silver; Oligonucleotides; DNA, Single-Stranded; Cysteine; Surface Plasmon Resonance; 01 natural sciences; Intercalating Agents; 0104 chemical sciences

We report the development of a surface plasmon resonance sensor based on the silver ion (Ag(+))-induced conformational change of a cytosine-rich, single-stranded DNA for the detection of Ag(+) and cysteine (Cys) in aqueous solutions. In the free state, single-stranded oligonucleotides fold into double-helical structures through the addition of Ag(+) to cytosine–cytosine (C–C) mismatches. However, in the presence of Cys, which competitively binds to Ag(+), the formation of the C–Ag(+)–C assembly is inhibited, resulting in free-state, single-stranded oligonucleotides. To enhance sensitivity, the DNA intercalator, daunorubicin, was employed to achieve signal enhancement. The detection limit for Ag(+) was 10 nM with a measurement range of 50–2,000 nM, and the detection limit for Cys was 50 nM with a measurement range of 50–2,000 nM. This simple assay was also used to individually determine the spiked Ag(+) concentration in water samples and Cys concentrations in biological fluid samples.