title: Detection of lead (II) with a "turn-on" fluorescent biosensor based on energy transfer from CdSe/ZnS quantum dots to graphene oxide.
abstract: Graphene oxide (GO) sheets are mixed with the aptamer-functionalized CdSe/ZnS quantum dots (QDs). Consequently, the aptamer-conjugated QDs bind to the GO sheets to form a GO/aptamer-QD ensemble, which enables the energy transfer from the QDs to the GO sheets, quenching the fluorescence of QDs. The GO/aptamer-QD ensemble assay acts as a "turn-on" fluorescent sensor for Pb(2+) detection. When Pb(2+) ions are present in the assay, the interaction of Pb(2+) with the aptamer induces a conformational change in the aptamer, leading to the formation of a G-quadruplex/Pb(2+) complex. As a result, the QDs that are linked to the G-quadruplex/Pb(2+) complex are detached from the GO sheet, which "turns on" the fluorescence of the QDs. This sensor exhibits a limit of detection of 90pM and excellent selectivity toward Pb(2+) over a wide range of metal ions. The experiments have provided direct evidence that the fluorescence of QDs is quenched by GO via the nano-metal surface energy transfer (NSET) mechanism rather than the conventional Förster resonance energy transfer (FRET) process.
authors.affiliation: Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Zhou
authors.forename: Shouwu
authors.initials: S
authors.lastname: Guo
authors.forename: Nianqiang
authors.initials: N
authors.lastname: Wu
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D019187:Cadmium Compounds / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D031541:Fluorescence Resonance Energy Transfer / Q000295:instrumentation*; D006108:Graphite / Q000737:chemistry*; D007854:Lead / Q000032:analysis* / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D010087:Oxides; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; D007854:Lead; D006108:Graphite; C058667:cadmium selenide; C031238:zinc sulfide