Near-infrared fluorescent probe based on the regulatory dye pKa for imaging of H2S in rice roots and living cells

[Display omitted] •NIR fluorescent probes based on regulatory dye pKa are synthesized for detecting H2S.•Probe A enables imaging detection of exogenous and endogenous H2S in living cells.•Probe A is able to monitor H2S levels of rice roots under salt stress and drought stress. Hydrogen sulfide (H2S) is a key factor in various biological processes such as plant grow and its response to environmental stress. Here, we develop a novel near-infrared (NIR) fluorescent probe for detecting hydrogen sulfide based on the regulatory NIR dye pKa values. After triggering the H2S substitution response, probe A with introducing the cyano moiety not only exhibits a significant near-infrared emission (Emax: 724 nm) response in physiological environments, but also shows a fast response, high selectivity, and sensitivity (LOD as 0.52 µM). In addition, probe A with low biological cytotoxicity is successfully used for imaging detection of cellular exogenous and endogenous hydrogen sulfide. More importantly, in situ imaging of probe A tracks the H2S fluctuations in the rice root system and its response to environmental stress. Hence, this work offers a new NIR fluorescence imaging monitoring tool for hydrogen sulfide in biological systems.