Development of “smart”
noninvasive bioimaging probes
for trapping specific enzyme activities is highly desirable for cancer
therapy in vivo. Given that β-galactosidase (β-gal) is
an important biomarker for cell senescence and primary ovarian cancers,
we design an enzyme-activatable ratiometric near-infrared (NIR) probe
(DCM-βgal) for the real-time fluorescent quantification and
trapping of β-gal activity in vivo and in situ. DCM-βgal
manifests significantly ratiometric and turn-on NIR fluorescent signals
simultaneously in response to β-gal concentration, which makes
it favorable for monitoring dynamic β-gal activity in vivo with
self-calibration in fluorescent mode. We exemplify DCM-βgal
for the ratiometric tracking of endogenously overexpressed β-gal
distribution in living 293T cells via the <i>lacZ</i> gene
transfection method and OVCAR-3 cells, and further realize real-time
in vivo bioimaging of β-gal activity in colorectal tumor-bearing
nude mice. Advantages of our system include light-up ratiometric NIR
fluorescence with large Stokes shift, high photostability, and pH
independency under the physiological range, allowing for the in vivo
real-time evaluation of β-gal activity at the tumor site with
high-resolution three-dimensional bioimaging for the first time. Our
work provides a potential tool for in vivo real-time tracking enzyme
activity in preclinical applications
