Green synthesis of high-performance seed tape using Camellia oleifera shells: DES-extracted nanolignin/chitosan composites for enhancing UV shielding and plant growth

The valorisation of agricultural byproducts into functional biomaterials presents a crucial pathway towards a circular economy and precision agriculture. Herein, we report a closed-loop strategy to synthesise high value-added seed tape by integrating nanolignin from Camellia oleifera shells with chitosan matrices. Lignin is extracted from Camellia oleifera shells using a choline chloride–lactic acid deep eutectic solvent. Subsequently, size-controlled lignin nanoparticles (LNPs) are synthesised via an antisolvent method. These LNPs are incorporated into a chitosan (CS) matrix to prepare a film for agricultural seed tape. The lignin extraction demonstrated a high yield of 93.3% with almost-complete cellulose depletion, affording a guaiacyl–syringyl– p -hydroxyphenyl (G–S–H) type. The incorporation of LNPs in CS markedly enhanced the properties of the CS films. Specifically, the tensile strength of the CS/LNPs5 composite film (14 wt% LNPs) increased by 71.85% and its ultraviolet shielding capability reached 99.90%. A germination rate of 85% was achieved with the CS/LNPs4 (11 wt% LNPs) when the seed tape was tested for radish. Compared with treatments without LNPs, the CS/LNPs composites promote root and stem elongation. This study establishes a closed-loop biorefinery framework that converts lignocellulosic agricultural residues into biomass-derived functional materials.