LAUSR

A novel one- and two-photon fluorescent probe based on a photoreaction was developed for the detection of cysteine (Cys). After it was reacted with Cys and illuminated by light, a strong turn-on fluorescence was observed at the excitation of 390 nm. The probe IC-2 was well tolerated at physiological pH conditions and exhibited a fast response rate to Cys within 10 min. Moreover, the probe IC-2 displayed high selectivity towards Cys among other amino acids and metal ions. Fluorescence response studies suggested that the limit of detection of IC-2 was calculated as 2.6 × 10-8 M. An MTT assay demonstrated that IC-2 had good cell permeability and low cytotoxicity to HepG2 cells. Notably, IC-2 was successfully applied in one- and two-photon fluorescence imaging for Cys in living cells and tissues.