Zirconium metal-organic cage integrated with fluorescein sodium: A dye-functionalized dual-emission platform for ratiometric sensing of sunset yellow

In present work, a dye-integrated composite material, FS@ZrT-1-NH 2 , was fabricated through a one-pot solvothermal method. The fabrication process involved the effective combination of fluorescein sodium (FS) with an amino-functionalized metal-organic cage (ZrT-1-NH 2 ) matrix. Subsequently, the as-prepared composite was employed as a dual-emission fluorescent probe for the targeted detection of sunset yellow (SY). Interaction energy and reduced density gradient (RDG) analyses revealed that hydrogen bonding interactions played a pivotal role in the stabilization of the composite. The unique dual-emission signal originated from efficient energy transfer between the cage and the embedded FS. This sensor exhibited a wide linear response to SY from 9.945 to 16.575 nM with a low detection limit of 0.980 nM, alongside remarkable selectivity. The fluorescence quenching mechanism was attributed to the synergistic effect of the inner filter effect (IFE) and static quenching. Notably, the proposed FS@ZrT-1-NH 2 ratiometric fluorescent probe achieved high recovery rates (102.02%–106.10%) and low relative standard deviations (RSD <3.1%) for SY detection in orange-flavored carbonated beverages, verifying its feasibility and practical applicability. These findings demonstrate that the dual-emission FS@ZrT-1-NH 2 composite can function as a highly promising platform for the sensitive and selective detection of SY.