Alloyed quaternary/binary core/shell quantum dot-graphene oxide nanocomposite: Preparation, characterization and application as a fluorescence “switch ON” probe for environmental pollutants

Abstract

Alloyed l-cysteine-capped CdSeTeS/ZnS quantum dots (QDs) have been covalently linked to graphene oxide (GO) to form a new QD-GO nanocomposite material. Transmission electron microscopy, scanning electron microscopy, Raman, energy dispersive X-ray spectroscopy, X-ray diffraction, FT-IR, UV/vis and fluorescence spectrophotometry were used to characterize the nanocomposite material. Covalent binding of GO to the QDs quenched the fluorescence (“switch OFF”) of the QDs. The planar structure of GO and its π electron rich surface enables the adsorption of π rich aromatic analytes. Environmental pollutants, belonging to the class of polycyclic aromatic hydrocarbons (PAHs) were used as model analytes to test their affinity to adsorb onto GO via π- π interaction and trigger fluorescence transduction changes (“switch ON”) in the conjugated QDs. Our investigation showed that the affinity of the four PAH analytes tested to switch on the fluorescence of the nanocomposite probe followed the order phenanthrene > anthracene > naphthalene > pyrene.