Dual-channel fluorescent imaging of reactive oxygen species in living cells based on Ce(III) modified quantum dots with oxidation triggered phosphatase-like activity

Abstract

The two-wavelength fluorescent sensing and imaging of reactive oxygen species (ROS) was demonstrated using Ce(III) ions modified fluorescent quantum dots (QDs). After the addition of ROS, the Ce(III) on the surface of QDs was transformed to Ce(IV) which exhibits phosphatase-like catalytic activity. The Ce(IV)/QDs can catalyze the hydrolysis of 4-methylumbelliferyl phosphate (4-MUP) to generate blue emission. On the other hand, ROS had only slight effect on the red fluorescent signal of QDs. Based on this phenomenon, the ratiometric fluorescent detection of ROS (ClO-, H2O2, and ONOO-) was successfully performed by using Ce(III)/QDs/4-MUP system. The two fluorescent emission peaks (450 nm and 620 nm) were well-separated, which holds the advantages such as high selectivity and accuracy. Finally, the Ce(III)/QDs/4-MUP system was successfully used for dual-channel fluorescent ROS imaging in HeLa and RAW264.7 cells.