Preparation of MOF-based tryptophan probe and its application in detection of biological products and food.

Tryptophan(Trp), an essential amino acid for the body, plays a crucial role in many physiological processes. Abnormal levels of tryptophan can be harmful to living organisms. Accurate real-time monitoring of its concentration is vital for maintaining health. Since the organism can only obtain tryptophan through external intake, the development of fluorescent probes for detecting tryptophan in various environments holds significant value. In this study, a Zr-MOF was synthesized using Zr4+ as the metal node, 1,2,4,5-benzenetetracarboxylic acid (H₄BTEC) and 4-carboxyphenylboronic acid (CPB) as organic ligands via a simple one-pot synthesis method, named UiO-66-COOH-B(OH)₂ (UBB). Subsequently, by virtue of the abundant carboxyl groups, UBB was post-synthetically modified with Eu3+ to form UiO-66-COOH-B(OH)₂ @Eu3+ (UBBE). UBB and UBBE were investigated as fluorescent probes for the detection of the Trp. UBBE probe demonstrated a significantly lower detection limit than UBB probe as 0.026 μM and 0.79 μM, respectively. Additionally, the UBBE probe exhibits good selectivity, stability, and other advantages, allowing successful detection in fetal bovine serum and various food samples.