Recyclable europium functionalized metal-organic fluorescent probe for detection of tryptophan in biological fluids and food products

An europium functionalized metal-organic fluorescent probe, Eu3+@UiO-66-FDC was constructed by post-synthetic modification through coordination interactions. Eu3+@UiO-66-FDC displayed high selectivity and sensitivity toward Tryptophan (Trp) among all the 20 natural amino acids and other general compounds in food and biological samples, with a wide linear concentration range (0–1000 μM), low detection limit (0.29 μM), and a rapid response (<1 min). Besides, this probe was utilized to detect Trp in rabbit blood serum and milk samples with good recoveries, which were verified by high-performance liquid chromatography (HPLC). Notably, this fluorescent probe proved to be a recyclable material. Hence, this work provides a reliable and recyclable fluorescent probe applicable toward the detection of Trp in biological fluids and/or food products.