Near-infrared fluorescent probe with large stokes shift for detecting Human Neutrophil elastase in living cells

Human Neutrophil elastase (HNE) plays a great role in immune responses and inflammation, and is associated closely with lung cancer and acute lung injury (ALI). Accurate detection of its activity is imperative to understand its biological function and diagnosing the disease states through monitoring the dynamic changes. Herein, we report a new NIR fluorescent probe (F-1) with large Stokes shift (182 nm). Probe F-1 featured high sensitivity (LOD ~ 5.6 ng/mL), good selectivity, low toxicity and a bright NIR emission triggered by HNE. Moreover, F-1 was successfully applied as an indicator to track the HNE in the A549 cells. Thus, F-1 may be an excellent tool for detecting enzymatic activity for preclinical applications and NE related diseases.