L-cysteine-capped core/shell/shell quantum dot-graphene oxide nanocomposite fluorescence probe for polycyclic aromatic hydrocarbon detection

TY - JOUR

T1 - L-cysteine-capped core/shell/shell quantum dot-graphene oxide nanocomposite fluorescence probe for polycyclic aromatic hydrocarbon detection

AU - Adegoke, Oluwasesan

AU - Forbes, Patricia B. C.

N1 - A postdoctoral fellowship offered by the University of Pretoria is gratefully appreciated by O. Adegoke. This work is based on research supported in part by the National Research Foundation of South Africa, Grant Numbers: 90720 and 93394 (P. Forbes), as well as the Department of Science and Technology (DST), South Africa, through the Photonics Initiative of South Africa (grant PISA-15-DIR-06), and the Water Research Commission, South Africa (grant K5-2438).

PY - 2016/1/1

Y1 - 2016/1/1

N2 - 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.

AB - 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.

KW - Absorption, Physicochemical

KW - Adsorption

KW - Cysteine/chemistry

KW - Environmental Pollutants/analysis

KW - Fluorescent Dyes/chemistry

KW - Nanocomposites/chemistry

KW - Oxides/chemistry

KW - Polycyclic Aromatic Hydrocarbons/analysis

KW - Quantum Dots/chemistry

KW - Solubility

KW - Spectrometry, Fluorescence

KW - Water/chemistry

U2 - 10.1016/j.talanta.2015.06.023

DO - 10.1016/j.talanta.2015.06.023

M3 - Article

C2 - 26695330

SN - 0039-9140

VL - 146

SP - 780

EP - 788

JO - Talanta

JF - Talanta

ER -