Fig. 1. The absorption and fluorescence spectra changes of MI-H₂O₂ (A and C) and ER-H₂O₂ (B and D) to H₂O₂. The excitation wavelength was 525 nm or 400 nm for MI-H₂O₂ and ER-H₂O₂, respectively. Inset: color changes of MI-H₂O₂ and ER-H₂O₂ solution (50 μM) in the absence or presence of H₂O₂ (500 μM).