Terbium (III)-referenced N-doped carbon dots for ratiometric fluorescent sensing of mercury (II) in seafood

A ratiometric fluorescence (FL) sensor was fabricated by coordinating 2, 6-pyridinedicarboxylic acid (DPA) sensitized Tb 3+ (Tb-DPA) with NH 2 and COOH on the surface of the N -doped carbon dots ( N -CDs) for detecting Hg 2+ in seafood. The sensor exhibited two FL emissions at 436 nm ( N -CDs) as the response signal and at 543 nm (Tb-DPA) as the reference signal when excited at 290 nm. After adding Hg 2+ , the FL emission at 436 nm was significantly quenched and the FL emission at 543 nm was negligibly changed. The electron transfer (ET) between COO − of N -CDs and Hg 2+ led to the FL quenching of N -CDs. The FL ratio (F 436 /F 543 ) exhibited a good linear relationship in the Hg 2+ concentrations of 1 161.51 μM with a low limit of detection (LOD) of ~37 nM. The sensor presented high selectivity, satisfactory accuracy and precision toward Hg 2+ in seafood with recoveries of 86.45–114.47% and RSDs of 0.20–1.92%.