Tailoring Nanomaterial Cross-Linkers through Lanthanide-Ligand Pairs: Guidance for Fine-Tuning the Structures and Properties of Luminescent Nanocomposite Hydrogels.

Integrating luminescent nanomaterials into hydrogels provides unique optical properties and improves their mechanical features for various applications. It is challenging but highly desirable to develop a versatile luminescent nanocomposite hydrogel system with tunable structures and properties to expand the potential uses of luminescent materials. Here, multiple amine-functionalized lanthanide-containing hydroxyapatites are synthesized as tailored nanomaterial cross-linkers to interact with polydextran aldehyde through imine bonds. The microstructure, gelation time, luminescence, rheological behavior, mechanical properties, thermal stability, degradation, and swelling capability of the luminescent lanthanide-containing nanocomposite hydrogels are systematically investigated. This study reveals that the strong binding affinity between surface metal ions and capping ligands of the nanomaterial cross-linkers contributes to the densest network and the highest mechanical properties of the nanocomposite hydrogels. In addition, these nanocomposite hydrogels possess dynamic features of self-healing, shear-thinning, and injectability, improving their suitability for advanced applications. The luminescent lanthanide-containing nanocomposite lyophilized hydrogels are also demonstrated in the differentiation of volatile organic compounds. Taken together, the adjustable microstructures and characteristics of this lanthanide-containing nanocomposite hydrogel system highlight its potential for offering guidance in producing diverse luminescent materials with definable performances across various fields.