A β-galactosidase activated near-infrared fluorescent probe for tracking cellular senescence in vitro and in vivo.

Cellular senescence is a steady state of cell cycle arrest necessary to maintain homeostasis in organisms. However, senescent cells may cause senescence in neighboring healthy cells, inducing the onset of several diseases, such as inflammation, neurological disorders, and atherosclerosis. Therefore, early detection of cellular senescence is extremely important. β-Galactosidase (β-gal), as a critical marker of cellular senescence, can be monitored to facilitate early diagnosis of aging-related diseases. Furthermore, β-gal is mainly found in lysosomes, which have a pH value of about 4.5-5.5. Here, we developed a near-infrared fluorescent probe (QMOH-Gal) for tracking cell senescence in vitro and in vivo via the detection of β-gal. In addition, the probe displayed high sensitivity and specificity for β-gal with good fluorescence signal in the acidity range. Subsequently, this QMOH-Gal probe was successfully employed to differentiate between normal cells and senescent cells by monitoring β-gal. Furthermore, the probe not only realized the monitoring of β-gal in zebrafish but also the tracking of β-gal in palbociclib-induced breast tumor senescence. Overall, the probe shows great promise as an effective tool for imaging β-gal in vivo for studying the biology of aging in organisms.