Dual-colored carbon dots-based ratiometric fluorescent sensor for high-precision detection of alkaline phosphatase activity

Probing the level and activity of alkaline phosphatases (ALP) is of great significance for biomedical research on cellular functions and clinical diagnosis of cancers. Herein, a novel dual-colored carbon dots (CDs)-based ratiometric fluorescent sensor was constructed to accomplish high sensitive and accurate determination of ALP relyed on the difference of fluorescence resonance energy transfer (FRET) between blue light emitted CDs (B-CDs)-MnO2 nanohybrid and yellow light emitted CDs (Y-CDs)-MnO2 nanohybrid. The ratiometric fluorescent sensor enabled sensitive discrimination of ALP against other enzymes in a linear range of 0.1-500 U/L with a limit of detection of 0.02 U/L. The lower error and signal fluctuation, more satisfactory LODs and higher R value (R-2 = 0.99552) of the ratiometric sensing platform than single signal detection mode (R-2 = 0.85231; R-2 = 0.64260) indicated the superiority of the ratiometric fluorescence detection mode. Besides, the excellent analytical performance towards ALP in biological system demonstrated the potential application in clinical diagnosis.