A mitochondria-targeted two-photon fluorescent probe for highly selective and rapid detection of hypochlorite and its bio-imaging in living cells

Two water-soluble carbazole-based two-photon fluorescent (TPF) probes (HCH and HCM) for ClO− detection were developed with rapid response, high selectivity and large two-photon absorption cross sections, which utilized the oxidative dehydrogenation of oxime to the nitrile oxide. It is found that the alkyl substituent groups in the cationic pyridinium moieties could affect the one-/two-photon luminescent properties of probes, and HCH was more suitable for ClO− detection than HCM thanks to the better stability of fluorescence, larger fluorescence enhancement folds and two-photon absorption cross sections for HCHCNO, the corresponding product of HCH toward ClO−. Bio-imaging study revealed that HCH could be used to detect ClO− in living cells under two-photon excitation, and co-staining experiments of HCH and MitoTracker Red FM (co-localization coefficient: 0.90) established that HCH was predominantly present in mitochondria.