Ultrasensitive and rapid dopamine sensing via turn-on fluorescence of a dual-ligand Tb-MOF: Towards point-of-care neurochemical monitoring.

Dopamine (DPA) plays a critical role in regulating various physiological systems, and its abnormal levels are associated with disorders such as neurodegenerative diseases, psychiatric disorders, drug addiction, and certain cancers. Therefore, the development of reliable, rapid, and sensitive methods for DPA determination is crucial for early diagnosis and effective treatment, particularly in clinical settings and point-of-care testing (POCT). In this study, a "turn-on" fluorescent probe was developed using a terbium-based metal-organic framework (Tb-MOF) constructed from dual ligands. This design addresses the drawbacks of traditional turn-off MOF sensors by enabling fluorescence enhancement upon dopamine (DPA) recognition, leading to improved sensitivity and selectivity. The dual-ligand Tb-MOF design strategically combines terephthalic acid for efficient Tb sensitization with 2-methylimidazole facilitating selective dopamine recognition. After only 3 min of incubation in phosphate buffer (pH 7.00) at room temperature, the assay enables immediate detection of DPA in plasma and urine samples following simple protein precipitation, supporting its suitability for POCT. This represents a clear advantage over many previously reported fluorescent probes that require longer incubation times or elevated temperatures. The proposed probe demonstrated high selectivity and sensitivity for DPA determination in human plasma and urine, with a wide linear range of 1.00 × 10 - 1.00 × 10 M and a low limit of detection of 2.05 × 10 M. These advantages highlight the potential of this dual-ligand Tb-MOF probe as a valuable platform for point-of-care testing aimed at early detection and monitoring of DPA-related disorders.