A novel Fluorescence Turn-on Sensor for Cr3+ Based on Fluorescence Resonance Energy Transfer Between Gold Nanoparticles and Rhodamine B

Up to now, “Turn-on” fluorescence sensor exhibits promising potential toward the detection of heavy metal ions, anions, drugs, organic dyes, DNA, pesticides and other amino acids due to their simple, quick detection, high sensitivity and selectivity. Herein, a novel fluorescence method of detecting Cr3+ in an aqueous solution was described based on the fluorescence resonance energy transfer between rhodamine B and gold Nanoparticles. The fluorescence of RhB solution could be obviously quenched (“off” state) with the presence of citrate-stabilized AuNPs. However, upon addition of Cr3+ to AuNPs@RhB system, the fluorescence of AuNPs was recovered owing to the strong interaction between Cr3+ and the specific groups on the surface of citrate-stabilized AuNPs, which will lead to the aggregation of AuNPs (“on” state). At this monment, the color of the reaction solution turned to black. Under optimal conditions, the limit of detection (LOD) for Cr3+ was 0.95 nM (S/N=3) with a linear range of 0.164 nM ~ 3.270 μM. Furthermore, the proposed method exhibits excellent performances, such as rapid analysis, high sensitivity, extraordinary selectivity, easy preparation, switch-on fluorescence response and non-time consuming.