1：Experimental Design and Method Selection:

The study involved designing and synthesizing a novel indolium-based fluorescent probe (probe 1) for detecting hypochlorite via a double oxidation reaction mechanism. Fluorescence and UV-vis spectroscopy were used to evaluate selectivity, sensitivity, and response time in CH3CH2OH/PBS solution.

2：Sample Selection and Data Sources:

Probe 1 was synthesized and tested with various analytes including anions and reactive oxygen species. Eca109 cells from the Cell Bank of the Chinese Academy of Sciences were used for bioimaging.

3：List of Experimental Equipment and Materials:

Equipment included a Bruker DTX-400 spectrometer for NMR, Hitachi F-7000 spectrophotometer for fluorescence, Agilent Cary 100 spectrometer for UV-vis, Thermo HPLC Q-Exactive HR-MS spectrometer for mass spectra, and Zeiss Axio Observer D1 inverted fluorescence microscope for cell imaging. Materials included sodium hypochlorite, other anions, and solvents like CH3CH2OH and DMSO-d

4：Experimental Procedures and Operational Workflow:

Synthesis of probe 1 was carried out via reaction in CH3CH2OH under nitrogen atmosphere, followed by purification. Spectroscopic measurements were performed in CH3CH2OH/PBS solution. Cell imaging involved incubating Eca109 cells with probe 1 and NaClO, then observing under a microscope.

5：Data Analysis Methods:

Fluorescence intensity changes were monitored, detection limit was calculated using 3σ/slope method, and mechanisms were confirmed via HR-MS spectra.