title: Highly selective and sensitive method for cysteine detection based on fluorescence resonance energy transfer between FAM-tagged ssDNA and graphene oxide.
abstract: In this work, a new platform for effective sensing cysteine (Cys) was developed based on fluorescence resonance energy transfer (FRET) between FAM-tagged single-stranded DNA (FAM-ssDNA) and graphene oxide (GO). Due to the noncovalent assembly between FAM-ssDNA and GO, fluorescence quenching of the FAM took place because of FRET. This method relied on the competitive ligation of Ag(+) by Cys and "cytosine-cytosine" (C-C) mismatches in a FAM-labeled DNA strand of the self-hybridizing strand. At first, enough amount of Ag(+) was introduced to bind "C-C" mismatches and form double-stranded DNA (dsDNA), which had weak affinity to GO and kept FAM away from GO surface. However, the presence of Cys removed Ag(+) away from "cytosine-Ag(+)-cytosine" (C-Ag(+)-C) base pairs, leading to the formation of ssDNA again and FRET, and then fluorescence of the FAM-ssDNA was efficiently quenched. The fluorescence intensity decrease was found to be proportional to the increase of concentration of Cys in both aqueous buffer (2-200 nM) and human serum (5-200 nM), and the sensitivity of the proposed method towards Cys was much higher than that of other reported assays for Cys.
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Liu
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Wang
authors.forename: Aiguo
authors.initials: A
authors.lastname: Shen
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhou
authors.forename: Jiming
authors.initials: J
authors.lastname: Hu
mesh_terms: D001483:Base Sequence; D002021:Buffers; D003545:Cysteine / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000235:genetics; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D010087:Oxides / Q000737:chemistry*; D012834:Silver / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D002021:Buffers; D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D010087:Oxides; D014867:Water; D012834:Silver; D006108:Graphite; D003545:Cysteine