Yellow emissive nitrogen-doped graphene quantum dots as a label-free fluorescent probe for Fe³⁺ sensing and bioimaging

Rapid and sensitive fluorescence nanomaterials sensor with satisfactory selectivity has gained numerous importance for detecting multiple metal ions. Graphene quantum dot (GQD) has attracted a great deal of attentions. Herein, yellow emissive GQDs with a high quantum yield of 0.34 were achieved by nitrogen-doping. The as-prepared N-GQDs exhibited excitation-independent behavior and high optical stability. Furthermore, based on the complexation between Fe³⁺ and N-GQDs, the fluorescence intensity of the N-GQDs could be greatly quenched by the addition of a small amount of Fe³⁺ ions. The linearity range is 0–80 μM with a detection limit of 63 nM. For this reason, the proposed method was demonstrated to be selective and suitable for Fe³⁺ analysis in natural water samples. And, N-GQDs with the biosafety have the potentials for intracellular Fe³⁺ detection.