Design and Synthesis of a New Terbium Complex-Based Luminescent Probe for Time-Resolved Luminescence Sensing of Zinc Ions

Luminescent probes/chemosensors based on lanthanide complexes have shown great potentials in various bioassays due to their unique long-lived luminescence property for eliminating short-lived autofluorescence with time-resolved detection mode. In this work, we designed and synthesized a new dual-chelating ligand {4′-[N,N-bis(2-picolyl)amino]methylene-2,2′:6′,2′-terpyridine-6,6′-diyl} bis(methylenenitrilo) tetrakis(acetic acid) (BPTTA), and investigated the performance of its Tb³⁺ complex (BPTTA-Tb³⁺) for the time-resolved luminescence sensing of Zn²⁺ ions in aqueous media. Weakly luminescent BPTTA-Tb³⁺ can rapidly react with Zn²⁺ ions to display remarkable luminescence enhancement with high sensitivity and selectivity, and such luminescence response can be realized repeatedly. Laudably, the dose-dependent luminescence enhancement shows a good linear response to the concentration of Zn²⁺ ions with a detection limit of 4.1 nM. To examine the utility of the new probe for detecting intracellular Zn²⁺ ions, the performance of BPTTA-Tb³⁺ in the time-resolved luminescence imaging of Zn²⁺ ions in living HeLa cells was investigated. The results demonstrated the applicability of BPTTA-Tb³⁺ as a probe for the time-resolved luminescence sensing of intracellular Zn²⁺ ions.