A chromenoquinoline-based two-photon fluorescent probe for the highly specific and fast visualization of sulfur dioxide derivatives in living cells and zebrafish.

Sulfur dioxide (SO2) derivatives play critical roles in various biological processes. Therefore, effective methods for monitoring SO2 are of vital importance in bisulfite/sulfite biology. In this study, a two-photon (TP) imaging probe (CQ-SO2) for detecting SO2 derivatives was designed and constructed, based on the chromenoquinoline (CQ) fluorophore and a β-chlorovinyl aldehyde sensing moiety. The TP properties of the CQ derivatives were revealed for the first time in this study. This study enriched the biological application range of CQ derivatives and also provided a new choice for the development of TP dyes. In particular, the CQ-SO2 probe exhibited a fast response time (about 5 s), low detection limit (16 nM) and ultrahigh specificity towards SO2 derivatives. Furthermore, the probe was successfully applied to the highly specific TP bioimaging of SO2 derivatives in living cells and zebrafish.