Rare-Earth hydroxide nanosheets based ratio fluorescence nanoprobe for dipicolinic acid detection.

We demonstrate a novel ratio fluorescence nanoprobe for dipicolinic acid (DPA) as an anthrax biomarker based on layered rare-earth hydroxide (LRH). 3-Amino-benzenesulfonic acid (AS) was intercalated into layered terbium hydroxide to form composite and then delaminated into nanosheets in formamide. The monolayer nanosheets were beneficial to expose the Ln3+ luminescence centers to the environment more completely, contributing a high sensitive detection to the environment. With the increase of DPA concentration, the emission intensity of AS kept constant which worked as a stable internal reference, while the fluorescence of Tb3+ was enhanced obviously due to the antenna effect. In the 0.05-5.0 μM concentration range, the I544/I360 fluorescence ratio changed with the DPA concentration, which exhibited a good linear relationship (R2 = 0.999) and an ultralow detection limit of 3.8 nM. In addition, the probe showed high selectivity and sensitivity to the DPA detection as an anthrax biomarker, which can be applied in real tap water with good performances. This work could extend the applications of LRH nanosheets in detection and offer an extremely effective and easy technique for detecting DPA.