A multifunctional fluorescent probe for sequential detection of Hg2+ and nitenpyram in living cells: rational design and mechanistic insights.

The deposition of heavy metal ions and pesticides has presented a significant threat to ecological systems and human health. Consequently, the development of rapid and highly efficient detection technologies is of critical importance. In this work, a novel fluorescent probe, N'-(2-butyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzo[b]thiophene-2-carbohydrazide (NDBC), was successfully designed and synthesized by incorporating naphthimide and acylhydrazine. The synthesized NDBC enables continuous detection of Hg2+ and nitenpyram based on a "turn-off-on" fluorescence signal response. When Hg2+ was added to the NDBC solution, the system showed a pronounced quenching phenomenon, with a detection limit of 0.12 μM. The NDBC was effectively employed for detecting environmental samples, including tap water, Songhua River water, and Nejiang River water, achieving recovery rates ranging from 98.15% to 102.13% and a relative standard deviation (RSD) between 1.03% and 4.47%. Upon introducing nitenpyram to the NDBC-Hg2+ complex, the fluorescence returned to its original level, achieving a detection limit of 0.31 μM. The system was effectively employed for detecting environmental samples, including tap water, Songhua River water, and Nejiang River water, achieving recovery rates ranging from 95.58% to 101.15% and a relative standard deviation (RSD) between 0.83% and 4.59%. Additionally, fluorescence biological imaging of Hg2+ and nitenpyram in living cells and zebrafish was successfully achieved. This work develops a new approach for the rapid detection of Hg2+ and nitenpyram, offering promise for application in both environmental and biological sample analysis.