Fig. 1. (A) Changes in fluorescence (FL) spectra of the ABD-system (10 μM) in PBS buffer solution in the presence of H₂O₂ (100 μM) for different times (0 to 90 min). (B) Plot of FL intensity versus incubation time. The data are extracted from the spectra in (A). (C) FL spectra of the ABD-system in PBS buffer solution incubated with different concentrations of H₂O₂ for 90 min; (D) plot of the relative FL intensity versus H₂O₂ concentration. The data are extracted from (C), and the inset photographs show the FL images of the stock solutions with and without H₂O₂. Concentration of the ABD-system (10 μM); PBS buffer solution (pH = 7.8, 10 mM, containing 1% DMSO); temperature: 37 °C; excitation wavelength: 330 nm for FL measurement and 365 nm for photograph.