1：Experimental Design and Method Selection:

The probe was designed based on a conjugated hybrid coumarin-hemicyanine compound, utilizing a 1,4-addition reaction mechanism for selective detection of HSO3?/SO32?. Fluorescence and UV-Vis spectroscopy were used for spectral analysis, and confocal microscopy for imaging in cells and zebrafish.

2：2?. Fluorescence and UV-Vis spectroscopy were used for spectral analysis, and confocal microscopy for imaging in cells and zebrafish. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: BT-474 human breast cancer cells and 3-day-old zebrafish were used as biological samples. Anions and biothiols were tested for selectivity.

3：List of Experimental Equipment and Materials:

Fluorescence spectrophotometer (Agilent Cary Eclipse), UV-Vis spectrophotometer (Agilent Technologies Cary 60), NMR spectrometer (Bruker AVANCE Ⅲ 600 MHz), mass spectrometer (Bruker ApexUltra 7.0 T), confocal microscope (Zeiss LSM 880), HEPES buffer, DMF, various anions, biothiols, MitoTracker Green, RPMI 1640 Medium, FBS, E3 embryo media.

4：0 T), confocal microscope (Zeiss LSM 880), HEPES buffer, DMF, various anions, biothiols, MitoTracker Green, RPMI 1640 Medium, FBS, E3 embryo media. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Synthesis of probe 1 via reaction of compound 3 and 2,3-dimethylbenzo[d]thiazol-3-ium iodide. Spectral titrations with HSO3? in HEPES buffer. Cell culture and incubation with probe and analytes. Zebrafish treatment and imaging. Co-localization studies with MitoTracker Green.

5：Data Analysis Methods:

Fluorescence intensity ratios (I490/I749) were used for ratiometric detection. Detection limit calculated based on signal-to-noise ratio (S/N=3). Pearson's coefficient for co-localization analysis. MTT assay for cytotoxicity.