A TICT based two-photon fluorescent probe for bisulfite anion and its application in living cells

A two-photon fluorescent probe (DMPCA) for the detection of bisulfite anion in water was developed based on twisted-intramolecular-charge-transfer (TICT) mechanism. Fluorescence intensity of DMPCA increased dramatically (65 fold) upon the addition of HSO3−. The two-photon absorption cross-section of DMPCA was found to be 725 GM at 700 nm upon the addition of HSO3−. The fluorescent probe showed an excellent selectivity for bisulfite anion over other anions. The nucleophilic addition reaction mechanism with aldehyde was confirmed with NMR and MALDI-TOF. The TICT detection mechanism was confirmed by viscosity-dependent fluorescence spectra and time resolved fluorescence spectra. Moreover, DMPCA was successfully applied to the detection of bisulfite anion in HeLa cells with low cytotoxicity under two-photon excitation.