A lysosomes-targeted ratio fluorescent probe for real-time monitoring of micropolarity in cancer cells

Lysosomal micropolarity-change is one of the ultimate reflection factors of cell apoptosis and death in complex living organism. Thus, rapid and sensitive detecting of lysosomal micropolarity-change is beneficial for real-time estimating of cancer cell apoptosis. Many polarity-specific fluorescent probes have been reported, but lysosomal micropolarity-ultrasensitive ratiometric fluorescent probe with excellent two-photon property for real-time estimating the cancer cell apoptosis is scarce. In this work, an intramolecular charge transfer (ICT) two-photon ratiometric fluorescent probe (DC) was reported and evaluated to real-time estimate cancer cell apoptosis through ultrasensitive detection of lysosomal micro-polarity. DC appeared different fluorescence intensities at 580 and 600 nm in cancer cells, specifically. And its fluorescence change presented a linear change on ratio mode in the range of polarity (Δf = 0.2230–0.3274). The lowest detection of DC for polarity change can as low as Δf = 0.018 by fluorescent ratiometric signals. More importantly, based on the ultrasensitive changes of lysosomal micro-polarity, DC can be used to real-time estimate cancer cell apoptosis by microscopic imaging and flow cytometry. Thus, DC may have potential application varying from detecting of lysosomal micropolarity changes to real-time estimating of cancer cell apoptosis.