In this work, we synthesized blue-fluorescent nitrogen-doped carbon quantum dots (N-CQDs) via a facile, economical, and environmentally friendly one-pot synthesis, using citric acid as the carbon source and polyethyleneimine (PEI) as the nitrogen dopant. The as-prepared N-CQDs exhibited uniform size distribution, with an average diameter of approximately 3 nm and a quantum yield of up to 23.6%. Based on the mechanism of HClO-triggered static fluorescence quenching and oxidation of surface amine groups on the N-CQDs, we established a quantitative detection platform for hypochlorous acid (HClO). The proposed method demonstrated a linear response over the concentration range of 0–40 μmol/L, with a detection limit as low as 0.17 μmol/L. It also featured a rapid response time (within 2 min), high selectivity, and strong anti-interference capability against various common species, including Cl−, H2O2, NO2−, NO3−, TBHP, TBO•, Br−, I−, S2−, F−, O2− and HO•. Furthermore, the probe was successfully applied to detect HClO in real-world samples such as river water and beer. Owing to its outstanding photostability and low toxicity, it proved highly effective for monitoring intracellular HClO in living cells.
Yan et al. (Fri,) studied this question.