A carbon dots-based ratiometric fluorescence probe for monitoring intracellular pH and bioimaging

Abstract It is highly desired to detect intracellular pH in terms of better awareness of biological processes and early diseases diagnosis. Herein, a new fluorescent and pH-dependent carbon dots-based ratiometric probe was developed by one-pot hydrothermal method, firstly using 8-aminoquinol and citric acid (CA) as precursors. It is confirmed that the probe shows diverse emission wavelengths at 365 and 439 nm when excited at 290 nm, which can better provide self-calibration for pH detecting. Especially, the intensity ratio (I439 /I365) is linear against pH within the range of 4.2−6.4. The nanoprobe shows satisfactory pH sensitivity, selectivity, reversibility, photostability and biocompatibility, low cytotoxicity, and operational simplicity. The nanoprobe was successfully used as a cells-imaging label to track pH changes, indicating that it has promising application in living systems.