A near-infrared fluorescent off-on probe with large Stokes shift for sensing hydrazine in vitro and in vivo

The development of effective approaches for detecting toxic hydrazine (N2H4) is of great importance for public health. In this work, a near-infrared (NIR) fluorescent probe (QLN-Hy) for trace hydrazine detection with a large Stokes shift was constructed. Hydrazine-activatable QLN-Hy displayed striking characteristics of high sensitivity (detection limit: 0.25 μM), high selectivity, as well as notable fluorescence enhancement at the NIR emission (692 nm) and large Stokes shift (104 nm). In particular, the color of QLN-Hy changed from purple to light blue, enabling the direct visualization of hydrazine in vapor and aqueous phases through the naked eye readily. Meanwhile, the practical feasibility of QLN-Hy was successfully evaluated by quantitatively detecting trace hydrazine in water samples (lake water, river water, rain water, tap water, drinking water) and mice samples (urine, serum). Importantly, probe QLN-Hy can be conveniently applied to monitor and visualizing hydrazine in cells and in vivo, clearly demonstrating its invaluable potential biological applications.