title: Surface plasmon resonance detection of silver ions and cysteine using DNA intercalator-based amplification.
abstract: 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.
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Chia-Chen
authors.initials: CC
authors.lastname: Chang
authors.forename: Shenhsiung
authors.initials: S
authors.lastname: Lin
authors.forename: Shih-Chung
authors.initials: SC
authors.lastname: Wei
authors.forename: Yu
authors.initials: Y
authors.lastname: Chu-Su
authors.forename: Chii-Wann
authors.initials: CW
authors.lastname: Lin
mesh_terms: D003545:Cysteine / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics; D007364:Intercalating Agents / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D009841:Oligonucleotides / Q000737:chemistry* / Q000235:genetics; D012834:Silver / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D004277:DNA, Single-Stranded; D007364:Intercalating Agents; D007477:Ions; D009841:Oligonucleotides; D012834:Silver; D003545:Cysteine