Design, Synthesis and Sensing Application of Novel Dual Lanthanide Doped Core–Shell Fluorescent Silica-Based Nanoparticles

The synthesis of lanthanide fluorescent nanoparticles and the investigation of their fluorescence sensing applications have attracted a great deal of attention in materials science over the past decades. In this study, we designed and synthesized a core-shell fluorescent nanoparticle based on dual-center emission from the europium and terbium complexes, and demonstrated its application as a ratiometric fluorescence sensor for the detection of 2,6-pyridinedicarboxylic acid (DPA). The europium complex is embedded in the inner core, providing a stable fluorescence signal at 617 nm, while the terbium complex is positioned in the outer shell and exhibits a fluorescence "Turn-ON" response at 545 nm upon interaction with DPA molecules. The fluorescence intensity ratio F₅₄₅/F₆₁₇ exhibits a sensitive response to the DPA concentration. Experimental results demonstrate that the as-prepared SiO₂@Eu@SiO₂@Tb nanoparticle exhibits a linear response in the DPA concentration range of 10-100 μM, with a detection limit (LOD) of 1.38 μM and well selectivity for DPA sensing. This strategy offers new insights into the development of novel lanthanide-based ratiometric fluorescence sensors.