Desirable photo-physicochemical properties of dicyanomethylene-4H-pyran probe enables long-term fluorescent tracking of lysosomal dynamics in live cells

Abstract

Most currently used small molecular lysosomal dyes usually fail in tracing the lysosomal long-term dynamics because of their inappropriate photophysical and photochemical properties, such as pH dependency and weak photostability. Therefore, it is of great interest to develop other lysosomal probes with desired photo-physicochemical properties for visualizing and tracking lysosomal dynamics. Here, the popular dicyanomethylene-4H-pyran (DCM) derivative DCM-OH was found to image lysosomes selectively with bright far-red fluorescence. Importantly, DCM-OH imaging was demonstrated to be pH-insensitive, highly photostable and low (photo-) cytotoxic, and it also exhibited high resistance to various other lysosomal microenvironmental changes (polarity and viscosity). All these properties enabled its qualification for long-term trace of lysosomal dynamics in live cells. At last, the applications of DCM-OH in photo-tracking lysosomal dynamic events, including fusion-fission, kiss-and-run process and mitophagy, were successfully observed. Therefore, the study demonstrates DCM-OH molecule is highly qualified for fluorescent visualization and real-time trace of lysosomes by overcoming the limitations of most commercial Lysosomal dyes thanks to its desirable photo-physicochemical properties.