A new near-infrared fluorescence indicator derived from chloro-substituted dicyanoisophorone for detecting carboxylesterases (CEs) in living cells and in vivo

Carboxylesterase (CEs) are a kind of liver-synthesized esterase and play a great role in various physiological activities such as drug metabolism and transport processes. Accurate detection of their activity through near-infrared (NIR) fluorescence probe with large Stokes shift is still needed to investigate their biological function and diagnose related disease in vivo . In present study, a new “off-on” fluorescent probe (ZM-1 ) was constructed with large Stokes shift (160 nm). ZM-1 could be used to detect CEs with a bright NIR emission in a concentration dependent and time-dependent manner. The detection line of ZM-1 is as low as 0.287 × 10 −3 U/mL. Moreover, ZM-1 possessed high selectivity and low toxicity. ZM-1 exhibited good optical performance to track CEs activity in cells and monitor the change of CEs activity on 5-Fu-induced model, indicating its good cell membrane permeability and precise detection character. More importantly, ZM-1 was successfully used to in situ image CEs activity in vivo . These studies suggest that probe ZM-1 has potential applicable valuation for CEs detection in living bio-systems and CEs-related disease diagnose. • We reported a new chloro-substituted dicyanoisophorone-based near-infrared probe ( ZM-1 ) for CEs detection. • ZM-1 exhibited high sensitivity (LOD∼ 0.287 × 10 −3 U/mL). • ZM-1 featured large Stokes shift (160 nm), low toxicity, selectivity for CEs detection. • ZM-1 was successfully applied to image CEs in living cells and in vivo.