Enhancing aqueous stability of supramolecular lanthanide-organic complexes by in situ polymerization for bio-imaging

Over the past several decades, multi-component supramolecular lanthanide-organic complexes have attracted considerable attentions owing to their unique physicochemical properties imparted by lanthanide ions. Nevertheless, most reported systems suffer from poor water solubility and intrinsic structural fragility, which severely limits their practical utility. Herein, we present a simple yet effective strategy to enhance the stability of lanthanide-organic complexes in water by embedding them into surfactant micelles (CTAB, F127). Photoluminescence measurements reveal that micelle-encapsulated complexes exhibit enhanced emission and maintain hour-level stability in aqueous solution. Furthermore, in situ polymerization of micelles formed from the polymerizable surfactant AUTEAB effectively suppresses dynamic exchange processes and yields robust hybrid materials. The overall Eu 3+ photoluminescence quantum yield ( Φ overall ) of the hybrid material Eu 4 L 1 4 @PAUTEAB reaches approximately 8.1% in water. Importantly, this enhanced emission is long-lived and resistant to competitive coordination by solvent molecules, anions, as well as to dilution. A second hybrid, Eu 2 L 2 3 @PAUTEAB, displays even stronger photoluminescence and demonstrates excellent tumor-cell imaging performance. This micelle-encapsulation and polymerization approach establishes a general route to stabilize lanthanide complexes in aqueous media and opens new opportunities for their deployment in biological imaging and related applications.