Figure 1.

(A) Absorption (solid lines) and fluorescence spectra (dotted lines) of CLN (10 μM) without (black) or with (red) Na₂S₂O₄ (0.4 mM). (B) Fluorescence spectra of CLN (10 μM) in different concentrations of Na₂S₂O₄ (0–0.4 mM). Inset: The linear correlation of the fluorescence intensities at 758 nm with the concentrations of Na₂S₂O₄. (C) Fluorescence spectra of SOSG (2 μM) in the CLN solution (10 μM) after NIR laser irradiation (660 nm, 0.2 W/cm²) at different time points (0, 10, 20, 30, 40, and 50 s). (D) Changes in the fluorescence intensities at 525 nm vs. the irradiation time. (E) Changes in the fluorescence spectra of CLN (10 μM) response to different NTR concentrations (0–5 µg/mL) with NADPH (500 μM) in PBS (10 mM, pH 7.4) containing 10% EtOH at 37 °C after 30 min of incubation. (F) Selectivities of the fluorescence responses of CLN (10 μM) to different species: NaCl (10 mM), MgCl₂ (10 mM), ZnSO₄ (10 mM), ClO⁻ (10 mM), H₂O₂ (10 mM), GSH (1 mM), Vc (1 mM), Cys (1 mM), Gly (1 mM), NADPH (500 μM), and NTR (5 μg/mL in the presence of NADPH (500 μM)) in PBS buffer at 37 °C in the presence of CLN (10 μM). Control: CLN (10 μM). All the samples were tested after 30 min of incubation.