A ratiometric fluorescent probe for aluminum ions based-on monomer/excimer conversion and its applications to real samples

Excessive amount of aluminum is detrimental to growing plants or animals and people are likely to suffer from various diseases upon long-term exposure to aluminum ions. Therefore, sensitive and selective detection of trace amounts of Al³⁺ in real samples is of great importance. Herein, a ratiometric fluorescent probe for detecting aluminum ions based on pyrene-1-butyric acid (Py-L-COOH) was developed, which function via monomer/excimer conversion. In the presence of Al³⁺, the original monomer-state Py-L-COOH molecules coordinate with Al³⁺ and form excimer, thus changing the emission wavelength from 350-400 nm to 450-500 nm and achieving the ratiometric detection for Al³⁺. The probe responds to Al³⁺ quickly and can be operable in aqueous media with a very low detection limit of 0.29 μM. This system is capable of detecting Al³⁺ in real samples and shows high selectivity. Furthermore, the probe exhibits low cytotoxicity and can be used in fluorescence imaging in Hela cell lines. The approach may provide an effective simple probe for aluminum ions determination with application to real samples, as well as offering insights for designing facile ratiometric fluorescent sensors.