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 mu M 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.