Fig. 2: In vitro “off-on-off” responses of probes for H₂S and ROS.

All experiments were performed with 10 μg mL⁻¹ NDPs or 2H-NDPs in PBS (1 mM, pH 7.4) at 37 °C. All 2H-NDP solution (10 μg mL⁻¹) was achieved by the addition of the H₂S (32 μM) to the NDP solution (10 μg mL⁻¹). Absorption spectra of (a) NDPs and (g) 2H-NDPs before and after incubation with their respective analytes (32 μM NaHS or 40 μM NaClO). NIR-II fluorescence spectra changes of (b) NDPs and (h) 2H-NDPs, as well as their corresponding NIR-II fluorescence images of (c) NDPs and (i) 2H-NDPs upon treatment with their respective analytes NaHS (0 – 32 μM) or NaClO (0 – 40 μM) following excitation at 1064 nm. The plot of the Flu./Flu.₀ (where Flu₀ indicates the fluorescence intensity of the NDPs at 1216 nm without NaHS and Flu. is the fluorescence intensity of NDPs or 2H-NDPs at 1216 nm in the presence of different concentrations of their respective analytes NaHS or NaClO, respectively) of (d) NDPs and (j) 2H-NDPs (n =3 independent samples; mean ± SD). The time-dependent Flu./Flu.₀ of the (e) NDPs and (k) 2H-NDPs upon addition of their respective analytes (n = 3 independent samples; mean ± SD). The Flu./Flu.₀ of (f) NDPs and (l) 2H-NDPs toward their respective analytes (n = 3 independent samples; mean ± SD).