Immobilization of Quantum Dots on Fluorescent Graphene Oxide for Ratiometric Fluorescence Detection of Copper Ions

Abstract

Graphene oxide with stable fluorescence has been synthesized and utilized to support and functionalize quantum dots for dual-emissive nanostructure construction. The two emissions from graphene oxide and quantum dots are differently and independently responsive to copper ions (Cu2+). The blue fluorescence of graphene oxide is very stable against Cu2+, whereas the red fluorescence from quantum dots can be selectively quenched, inducing the composite fluorescent color change from bright red to blue. Such a novel nanocomposite can be applied for selective and sensitive determination of Cu2+. For practical application, the graphene based nanohybrid has been immobilized in polymer film to fabricate fluorescence test strip for Cu2+. A visual detection limit of 0.1 μM for the film test strip has been estimated and shows the potential application for on-site visual determination of Cu2+ with no need for elaborate equipment.