A dual-excitation fluorescent probe EuIII-dtpa-bis(HBT) for hydrazine detection in aqueous solutions and living cells

Abstract

Based on the esterification of 2-(2-hydroxyphenyl)benzothiazole (HBT) and a rare-earth metal ion complex Eu^III-dtpa, a novel dual-excitation fluorescence probe, Eu^III-dtpa-bis(HBT), was developed for the detection of hydrazine (N₂H₄). The structure of dtpa-bis(HBT) was characterized via FT-IR and NMR, and its optical properties were studied via UV-vis absorption and fluorescence spectroscopy. Influencing factors including solution acidity, interfering substances and N₂H₄ concentrations were considered for the detection of N₂H₄ using Eu^III-dtpa-bis(HBT). Eu^III-dtpa-bis(N₂H₄) and HBT emit significant fluorescence at 470 nm (λ_ex = 270 nm) and 480 nm (λ_ex = 325 nm), respectively. The detection limit of Eu^III-dtpa-bis(HBT) with N₂H₄ was 0.283 μM (14 ppb) and 0.182 μM (9 ppb) upon excitation at 270 nm and 325 nm, which is close to and lower than the EPA standard (10 ppb), respectively. The mechanism for the detection of N₂H₄ by Eu^III-dtpa-bis(HBT) was deduced from the experimental results and theoretical calculations. Also, cytotoxicity and cell imaging experiments of Eu^III-dtpa-bis(HBT) were performed. The experimental results showed that the fluorescent probe Eu^III-dtpa-bis(HBT) can be applied to detect N₂H₄ in aqueous solution and living cells.