Water soluble 1,8-naphthalimide fluorescent pH probes and their application to bioimagings

Two water soluble and high selective 1,8-naphthalimide fluorescent probes for protons have been synthesized by simple and efficient one-step reaction under very mild conditions. Their photophysical characteristics in Britton–Robinson buffer have been studied. All detections were carried out in aqueous media and a large number of biologically relevant ions showed no obvious interferences with the detection. Fluorescent imaging of living cells treated with the probe in different pH media indicated that the probe could provide extracelluar pH information by the cell's fluorescence.

► We report two water soluble and high selective fluorescent pH probes.
► The probes are synthesized by simple and efficient one-step reaction.
► All detections can be carried out in aqueous media.
► A large number of biologically relevant ions showed no obvious interferences.
► The probes can provide extracelluar pH information by living cell imaging.