title: L-cysteine-capped core/shell/shell quantum dot-graphene oxide nanocomposite fluorescence probe for polycyclic aromatic hydrocarbon detection.
abstract: Environmental pollutants, such as the polycyclic aromatic hydrocarbons (PAHs), become widely distributed in the environment after emission from a range of sources, and they have potential biological effects, including toxicity and carcinogenity. In this work, we have demonstrated the analytical potential of a covalently linked L-cysteine-capped CdSeTe/ZnSe/ZnS core/shell/shell quantum dot (QD)-graphene oxide (GO) nanocomposite fluorescence probe to detect PAH compounds in aqueous solution. Water-soluble L-cysteine-capped CdSeTe/ZnSe/ZnS QDs were synthesized for the first time and were covalently bonded to GO. The fluorescence of the QD-GO nanocomposite was enhanced relative to the unconjugated QDs. Various techniques including TEM, SEM, HRSEM, XRD, Raman, FT-IR, UV/vis and fluorescence spectrophotometry were employed to characterize both the QDs and the QD-GO nanocomposite. Four commonly found priority PAH analytes namely; phenanthrene (Phe), anthracene (Ant), pyrene (Py) and naphthalene (Naph), were tested and it was found that each of the PAH analytes enhanced the fluorescence of the QD-GO probe. Phe was selected for further studies as the PL enhancement was significantly greater for this PAH. A limit of detection (LOD) of 0.19 µg/L was obtained for Phe under optimum conditions, whilst the LOD of Ant, Py and Naph were estimated to be ~0.26 µg/L. The fluorescence detection mechanism is proposed.
authors.affiliation: Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Lynnwood Road, Pretoria 0002, South Africa. Electronic address: adegoke.sesan@mailbox.co.za.
authors.forename: Oluwasesan
authors.initials: O
authors.lastname: Adegoke
authors.affiliation: Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Lynnwood Road, Pretoria 0002, South Africa. Electronic address: patricia.forbes@up.ac.za.
authors.forename: Patricia B C
authors.initials: PB
authors.lastname: Forbes
mesh_terms: D065966:Absorption, Physicochemical; D000327:Adsorption; D003545:Cysteine / Q000737:chemistry*; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry*; D045663:Quantum Dots / Q000737:chemistry*; D012995:Solubility; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D005456:Fluorescent Dyes; D010087:Oxides; D011084:Polycyclic Aromatic Hydrocarbons; D014867:Water; D003545:Cysteine
keywords: Adsorption; Fluorescence sensor; Graphene oxide; Photoluminescence; Polycyclic aromatic hydrocarbon; Quantum dots