Reply to Comment on "Water-Soluble Fluorescent Probe with Dual Mitochondria/Lysosome Targetability Superoxide Detection in Live Cells and in Zebrafish Embryos".

Recently, we published a paper on the detection of superoxide (O2•-) with a water-soluble fluorescent probe (ACS Sens. 2018, 3, 59-64), and Francesco Tampieri et al. provided comments on our publication, mostly on the detection medium (deionized water) we used. Herein we present our responses to the addressed questions to explain that although KO2 decomposes in aqueous environment, the results we obtained did not affect the general trend, since evidence from the literature afforded the correlation between KO2 in aqueous media as a surrogate of superoxide and enzymatically produced O2•- for the probes wherein the deprotection pathway operated. Moreover, fluorescence imaging on cells and zebrafish embryos under PMA stimulation confirmed the effectiveness of our probe to detect superoxide using KO2 as a convenient source. The detailed studies from Francesco Tampieri and coauthors are scientifically meaningful for the reliable evaluation of fluorescent probes using KO2 as a surrogate of superoxide.