A fluorometric method for mercury(II) detection based on the use of pyrophosphate-modified carbon quantum dots

Pyrophosphate-modified carbon quantum dots (PP-CDs) are demonstrated to be a viable fluorescent nanoprobe for mercury(II) (Hg²⁺) detection. Hg²⁺ reacts with the pyrophosphate groups on the surface of PP-CDs to form a non-fluorescent complex. This results in quenching of the green fluorescence which has excitation/emission peaks at 400/513 nm. Static quenching is shown to be the dominant mechanism. The probe works in 0.1 μM to 1.4 μM Hg²⁺ concentration range, and the limit of detection is 2 nM. The PP-CDs were also used to visualize Hg²⁺ inside human hepatocyte LO2 cells. Graphical abstract Schematic representation of pyrophosphate-modified carbon quantum dots (CDs) for selective and sensitive fluorometric determination of mercury(II). Hg(II) quenches the blue fluorescence of the CDs, and glutathione restores it. The method was used to detect Hg(II) in spiked tap water and inside cells.