Novel dual-color fluorescence probe for monitoring the fluctuation of lysosomal polarity and viscosity during apoptosis

Apoptosis is pivotal in the pathogenesis of cancer and various other diseases. Real-time monitoring of apoptosis is crucial for assessing cell viability and facilitating drug screening. The process of apoptosis tends to cause changes in cellular microenvironmental factors. The variations of the microenvironment can serve as an indicator of the degree of apoptosis. Thus, the development of a smart and facile probe responding to cellular microenvironmental factors is significant for visualizing the apoptotic process. In this research, we designed a novel dual-color fluorescent probe, Lyso-DCPV, which incorporates N, N-diethyl coumarin as its polarity-responsive module, and the twisting double bond between N, N-diethyl coumarin and N-propyl quinoline as its viscosity-responsive module. The green fluorescence of Lyso-DCPV is sensitive to polarity changes, diminishing as polarity increases. Conversely, the red fluorescence intensifies with escalating viscosity. The probe specifically targets lysosomes, producing green fluorescence in live cells. Due to Lyso-DCPV's acute sensitivity to changes in polarity and viscosity, it is well-suited to observe variations in the intracellular lysosomal microenvironment during druginduced apoptosis. We also employed Lyso-DCPV for the dynamic assessment of polarity and viscosity during peroxide-induced apoptosis, enabling the observation of cell viability through variations in the probe's emission color and intensity. The distinct probe will pave the way for novel strategies in evaluating apoptosis-related drugs. Moreover, Lyso-DCPV stands as an exemplary molecular instrument to elucidate the interplay between polarity and viscosity, facilitating the exploration of the interrelation in the cellular microenvironment during apoptosis.