A highly sensitive fluorescent acidic pH probe based on rhodamine B diethyl-2-aminobutenedioate conjugate and its application in living cells

A highly sensitive fluorescent acidic pH probe based on rhodamine B-2-aminobutenedioate conjugate, was designed and synthesized. When the H+ concentration falls within the pH range of 4.0–6.5, the spirolactam unit of rhodamine B-2-aminobutenedioate was opened, which resulted in the dramatic enhancement of both fluorescence and absorbance intensity as well as the color change of the solution. Background metal ions showed small or no interference with the detection of H+. Confocal laser scanning microscopy experiments showed that rhodamine B-2-aminobutenedioate can be applied to detect acidic pH variations in living cells with a turn-on signal.

► The probe provides fluorescence and color changes within the pH range of 6.0–4.0.
► The probe can be reversibly performed to detect pH variation.
► The probe can be used to detect acidic pH variations in living cells.
► The effect of common metal ions on pH measurement is negligible.