DNA supported graphene quantum dots for Ag ion sensing.

The use of graphene quantum dots can be extended for bio-sensing and metal ion detection. Synergistic combination of graphene quantum dots (GQDs) with DNA leads to high performance Ag-ion detection system. The thoroughly characterized GQDs were found to have spherical morphology, with dimensions in the range of 5-10 nm. The atomic force microscopy studies proved that the synthesized GQDs were mostly comprised of two to four graphene layers. To make the system biocompatible, GQDs/NGQDs were combined with DNA. Two properties of DNA were exploited, capacity to provide nitrogen to GQDs; and to synergistically contribute to Ag detection. In addition to Ag, the strong green photoluminescence (PL) of GQDs showed significant quenching, owing to the appearance of associated Förster resonance energy transfer processes. This led to high sensing efficiencies.