Rational design of a highly efficient two-photon fluorescent probe for tracking intracellular basal hypochlorous acid and its applications in identifying tumor cells and tissues

The accurate and sensitive determination of basal hypochlorous acid (HOCl) in the biosystems is critical for unraveling its various physiological and pathological functions. Additionally, recent studies have shown that cancer cells possess higher concentration HOCl than normal cells. However, related studies about the discrimation of tumor cells and tissues from normal cells and tissues by using a simple HOCl probe have seldom been reported. Herein, we presented a simple, water-soluble, two-photon long-wavelength fluorescent probe TPFR for detecting HOCl with outstanding selectivity over other potential interfering substances. The fluorescence titration experiments demonstrated that probe TPFR was capable of quantitatively detecting 0-500 nM HOCl (DL = 0.9 nM). Additionally, the rapid response ( < 1 min) of probe TPFR for HOCl facilitated the detection of HOCl with high reactivity and short-time in the biosystems. The outstanding sensing performances of probe TPFR enabled it to be used to track intracellular basal HOCl and differentiate cancer cells from normal cells. Furthermore, probe TPFR was successfully used to discriminate tumor tissues from normal tissues in mice by two-photon excitation microscopy.