Recent Advances of Molecular Optical Probes in Imaging of β-Galactosidase

beta-Galactosidase (beta-Gal), as a lysosomal hydrolytic enzyme, plays an important physiological role in catalyzing the hydrolysis of glycosidic bonds which convert lactose into galactose. Moreover, upregulation of beta-Gal is often correlated with the occurrence of primary ovarian cancers and cell senescence. Thereby, detection of beta-Gal activity is relevant to cancer diagnosis. Optical imaging possesses high spatial and temporal resolution, high sensitivity, and real-time imaging capability. These properties are beneficial for the detection of beta-Gal in living systems. This Review summarizes the recent progress in development of molecular optical probes for near-infrared fluorescence (NIRF), bioluminescence (BL), chemiluminescence (CL), or photoacoustic (PA) imaging of beta-Gal in biological systems. The challenges and opportunities in the probe design for detection of beta-Gal are also discussed.