A ratiometric fluorescent nanosensor for the detection of silver ions using graphene quantum dots

A ratiometric fluorescent nanosensor has been developed for probing Ag+ ions based on the fluorescence resonance energy transfer (FRET) between graphene quantum dots (GQDs) and 2,3-diaminiophenazine (DAP) yielded from the Ag+ ions-oxidized o-phenlyenediamine (OPD). [Display omitted] •A novel ratiometric fluorescent nanosensor for Ag+ ions was established with GQDs.•The oxidase-like activity of Ag+ ions towards OPD was employed for the design of this nanosensor.•A FRET mechanism between GQDs and DAP was demonstrated.•This rationmetric fluorescent nanosensor can detect Ag+ ions in water samples. A ratiometric fluorescent nanosensor was reported for the first time for the sensitive and selective analysis of Ag+ ions by employing graphene quantum dots (GQDs) as the reference fluorophore and o-phenylenediamine (OPD) as the specific recognition probe. Upon the addition of Ag+ ions, OPD could be oxidized to produce 2,3-diaminophenazine (DAP) with a strong fluorescence emission at 557nm, whereas the fluorescence of GQDs at 445nm would be simultaneously quenched by the so generated DAP through fluorescence resonance energy transfer (FRET). A ratiometric fluorescent Ag+ nanosensor was thus developed. The fluorescence intensity ratios of DAP to GQDs linearly increased with the increasing of Ag+ concentrations in the range of 0–115.2μM, with a detection limit down to 250nM. Furthermore, the feasibility of practical applications of the developed detection strategy for probing Ag+ ions in real water samples was demonstrated.