Dual-Emission Fluorescent Probe for the Simultaneous Detection of Nitrite and Mercury(II) in Environmental Water Samples Based on the Tb3+-Modified Carbon Quantum Dot/3-Aminophenylboronic Acid Hybrid

Nitrite (NO2–) and mercury (Hg2+) ions are recognized as two typical inorganic contaminations that can cause severe damage to the environment and humans. In this paper, the energy transfer from carbon quantum dots (CQDs) to Tb3+ by the antenna effect was found, which can promote the f–f transition of Tb3+ and emit strong characteristic fluorescence of Tb3+. Based on CQD-Tb3+ and 3-aminophenylboronic acid (APBA), which have respectively sensitive and specific fluorescent response to NO2– and Hg2+ with different fluorescent signals, a dual-emission fluorescent probe of the CQD-Tb3+/APBA hybrid was thus fabricated for the simultaneous detection of NO2– and Hg2+ in environmental water samples. They emit dual-emission fluorescence peaks centered at 373 and 545 nm, respectively. A good linearity between the quenching efficiency of (F0 – F)/F0 and the concentrations of NO2– and Hg2+ was in the range of 5.0–1200.0 nM for NO2– and 0.1–6.0 μM for Hg2+. The limit of detection (LOD, 3σ/K) is ultrasensitive for NO2– (2.0 nM), and the LOD for Hg2+ is 38.1 nM. The dual-emission fluorescent probe was successfully applied for the determination of NO2– and Hg2+ in various environmental water samples. The possible luminescence and fluorescence quenching mechanisms of the probe are also discussed in detail. This study provides a new approach for fabricating a multifunctional fluorescent probe or sensor and a prospective application in environmental monitoring.