Fig. 1. Spectroscopic properties of RSTPP. (a) Absorption and (b) fluorescence emission spectra of RSTPP (2.5 μM) in pH 7.4 PBS (1) before and (2) after reaction with HOCl (2.5 μM) for 2 min. Insets: the corresponding color changes of RSTPP before and after the reaction. (c) Fluorescence response of RSTPP (10 μM) to HOCl at varied concentrations (0–35 μM). Insert: linear fitting curve of ΔF against the concentration of HOCl. ΔF is the fluorescence intensity difference of RSTPP with and without HOCl. (d) Fluorescence responses of RSTPP (10 μM) to various ROS in PBS (pH 7.4): HOCl (100 μM), ONOO– (200 μM), NO (100 μM), H2O2 (100 μM), ˙OH (100 μM), NO2 – (100 μM), O2 – (100 μM), 1O2 (100 μM), TBHP (100 μM), and TBO˙ (100 μM). λ ex/em = 553/580 nm.
