Ternary deep eutectic solvent fractionation of bamboo for bioethanol and pH-responsive lignin nanocarriers

Achieving efficient delignification while preserving the native structure of lignin remains a critical challenge for integrated bamboo biorefineries. In this study, a ternary deep eutectic solvent (DES) composed of (Benzyltriethylammonium chloride) TEBAC, ethylene glycol (EG), and p-toluenesulfonic acid (p-TsOH) was developed for bamboo fractionation. The optimized TEBAC/EG/p-TsOH system removed up to 97.94% of lignin and 85.99% of hemicellulose, while retaining 84.46% of cellulose. The pretreated bamboo showed significantly improved enzymatic saccharification, achieving a glucose yield of 78.98% and an ethanol yield of 73.16% following fermentation. The recovered lignin, characterized by a low molecular weight and well-preserved β-O-4 linkages, self-assembled into uniform lignin nanoparticles (LNPs) with approximately 318 nm. These LNPs efficiently encapsulated difenoconazole (Dif@LNP-140°C) with an encapsulation efficiency of 70.02%, exhibiting excellent photostability and pH-responsive release and full antifungal activity against Fusarium spp. Molecular dynamics simulations revealed that synergistic non-covalent interactions, particularly hydrogen bonding with G-units and π-π stacking with S-units, govern the stable encapsulation of the drug. This work presents a sustainable lignin-first strategy for integrated bamboo valorization, enabling the co-production of biofuels and lignin-based nanomaterials while maximizing resource efficiency.