A novel recyclable magnetic nanostructure for highly sensitive, selective and reversible detection of zinc ions in aqueous solutions

The synthesis and characterisation of a novel dansylated magnetic nanostructure, namely Fe3O4@SiO2-PEG-DnS, is reported here. Investigations of its fluorescent properties showed that the presence of the PEG moiety significantly enhanced the fluorescent intensity of the nanostructure when compared to both the free dansyl fluorophore and a nanostructure that contained no PEG spacer between the core and the attached dansyl group. The addition of zinc (Zn2+) ions to the aqueous suspension of Fe3O4@SiO2-PEG-DnS led to a 12.5-fold decrease in intensity. The quenching was selective to only Zn2+. No interference was observed by other examined metal cations, including cadmium (Cd2+). A very low detection limit of 6.00 nM in relation to zinc ions was demonstrated. In addition, the newly developed magnetic nanostructured chemosensor was found to be highly stable, reusable and recoverable.