Novel fluorescent probe for the ratiometric detection of β-galactosidase and its application in fruit.

A ratiometric fluorescent probe (Probe 1) was developed for the sensitive detection of β-galactosidase (β-gal) activity. Probe 1 detected β-gal activity in the range 0-1.0 U/mL, with a limit of detection of 0.025 U/mL. In addition, as different activities of β-gal added, the luminescent intensity of Probe 1 gradually increased, as observed under a 365 nm ultraviolet lamp. Moreover, this method is low-volume, 20 μL, and time-efficient, 45 min per measurement. Probe 1 was successfully used to measure the β-gal activity in real fruit samples in a qualitative manner, by the naked eye, fast semi-quantitative manner, by smartphone, or quantitative manner, by fluorescence spectrometer.