1：Experimental Design and Method Selection:

The study involved the synthesis of a tetrahydroquinoxaline iminocoumarin-based NIR fluorescent probe (NIR-IC-H2S) for H2S detection. The probe's design rationale was based on the thiolysis of the 2,4-dinitrobenzenesulfoamide group mediated by H2S.

2：2S. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: HeLa cells and RAW

3：7 cells were used for cell imaging experiments. Kunming mice were used as the animal model for in vivo detection. List of Experimental Equipment and Materials:

2 A Varian Mercury 600 spectrometer for NMR spectra, a Waters E2695 LC-MS system and a Bruker microTOF-Q instrument for mass spectra, an Agilent Cary 100 UV-Vis spectrophotometer for absorption spectra, an Agilent Cary Eclipse fluorescence spectrophotometer for fluorescence measurements, an inverted fluorescence microscopy (OLYPUS) for cell images, and a Bruker In Vivo-Xtreme imaging system for mice images.

4：Experimental Procedures and Operational Workflow:

The probe's response to H2S was tested in HEPES buffer. Cell imaging involved incubating cells with the probe and then with NaHS. In vivo imaging involved injecting mice with the probe and then with NaHS.

5：Data Analysis Methods:

Fluorescence intensity changes were monitored at 652 nm. The detection limit was determined using the 3σ method.