High-value valorization of industrial waste lignin into bioactive UV-shielding nanocomposites via a green supramolecular assembly strategy.

Although lignin is an abundant industrial by-product with intrinsic UV-blocking capabilities, its high-value valorization is severely hampered by its undesirable dark coloration and aggregation-induced quenching effects. Herein, this study presents a facile and eco-friendly biomacromolecule-assisted assembly strategy to upgrade lignin waste into visible-light transparent nanocomposites Z2L for advanced photoprotection. By leveraging the deprotonated phenolic sites of lignin as nucleation templates, molecular-level confinement of lignin chains within the Zeolitic Imidazolate Framework-8 was achieved. This spatial isolation effectively disrupts the extensive π-π stacking of lignin aggregates, simultaneously resolving the aesthetic bottleneck and amplifying UV absorption efficiency by 5.9-fold compared to pristine lignin. The engineered nanocomposites exhibit enhanced hydrophilicity, excellent thermal stability, and improved biocompatibility. Evaluations using murine models and porcine skin demonstrate that Z2L acts as a robust physical barrier effectively preventing UV-induced epidermal damage. Furthermore, the nanocomposites demonstrate integrated multifunctionalities, offering potent antioxidant activity and antibacterial defense against Staphylococcus aureus and Escherichia coli. This work presents a sustainable biorefinery paradigm for transforming industrial biomass waste into high-performance functional materials, offering a value-added alternative to synthetic UV filters.