title: Detection of Ag⁺ ions and cysteine based on chelation actions between Ag⁺ ions and guanine bases.
abstract: A selective and sensitive fluorescence biosensor for Ag(+) ions and cysteine (Cys) was developed based on the chelation actions between Ag(+) ions and guanine bases of G-rich fluorogenic oligonucleotide (FAM-ssDNA) and the different electrostatic affinity between FAM-ssDNA and graphene oxide (GO). FAM-ssDNA adsorbed onto the surface of GO through π-π stacking interaction between the ring structure in the nucleobases and the hexagonal cells of GO, and the fluorescence of the dye was quenched. In the presence of Ag(+) ions, the random coil structure changed into a G-Ag(+) architecture. As a result, the binding released FAM-ssDNA signal probe from the surface of GO, which disrupted the energy transfer from FAM-ssDNA to GO, recovering the fluorescence emission of FAM-ssDNA. On the other hand, because Cys was a strong Ag(+) ions binder, it could deactivate the sensor fluorescence by rewrapping FAM-ssDNA around GO. In this way, these changes in fluorescence intensity allowed the selective detection of Ag(+) ions and Cys.
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Chen
authors.forename: Yinran
authors.initials: Y
authors.lastname: Chen
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhou
authors.forename: Jiming
authors.initials: J
authors.lastname: Hu
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002414:Cations, Monovalent / Q000032:analysis; D002614:Chelating Agents / Q000737:chemistry; D003545:Cysteine / Q000032:analysis*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry; D006147:Guanine / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D012680:Sensitivity and Specificity; D012834:Silver / Q000032:analysis*
chemical_list: D002414:Cations, Monovalent; D002614:Chelating Agents; D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D009841:Oligonucleotides; D010087:Oxides; D012834:Silver; D006147:Guanine; D006108:Graphite; D003545:Cysteine