Design of a ratiometric two-photon probe for imaging of hypochlorous acid (HCLO) in wounded tissues

HCIO plays crucial roles in a wide range of biological and pathological processes. Recent studies have revealed that the generation of HCIO has close links with the wound healing process. It's thus meaningful to develop a reliable method for monitoring HCIO in wounded tissues. Toward this purpose, we herein report a rationally designed quinolone-based ratiometric two-photon fluorescent probe, QCIO, for HCIO. The probe QCIO rapidly displays a drop in blue emission and an increase of green emission in response to HCIO due to the oxidation of oxathiolane. The fluorescence intensity ratio (green/blue) can serve as the ratiometric detection signal for HCIO with high sensitivity. After confirming its excellent sensing performance in vitro, the probe was validated by detecting exogenous and endogenous HCIO in living cells. The probe was capable of monitoring HCIO in situ in the wounded tissues of mice by two-photon microscopy, which demonstrated the production profile of HCIO during the wound-healing process. This work affords a simple and reliable tool for the detection and imaging of HCIO, which promises to find more applications in HClO-related biological and pathological studies.