Novel supramolecular deep eutectic solvents-mediated lignin extraction and reduced cellulase non-productive binding...

The biorefining of bamboo is constrained by lignin, as its recalcitrance impedes valorization and inhibits enzymatic hydrolysis via cellulase non-productive binding. The present study designed and evaluated a novel supramolecular deep eutectic solvent (SUPRADES), composed of glycolic acid, betaine, and β-cyclodextrin (β-CD), for selective lignin extraction from Bambusa emeiensis and then for assessing its impact on enzymatic hydrolysis. The SUPRADES (glycolic acid/betaine/β-CD, 4:1:2 wt%) pretreatment achieved a high lignin yield of 66.6% at 140 °C, while yielding lower molecular weight lignin at 120 °C over a 6 h of pretreatment. The incorporation of β-CD facilitated lignin solubilization and yielded lower molecular weight fragments, thereby weakening their affinity for cellulase and reducing non-productive binding. This effect was corroborated by a decrease in the enzyme adsorption ratio from 70.65% to 58.15%. Structural analyses indicated the extracted lignin possessed favorable valorization characteristics, including a higher S/G ratio and increased phenolic hydroxyl content, compared to the system without β-CD. In parallel, the SUPRADES pretreatment also mitigated lignin redeposition, thereby improving cellulose accessibility and enhancing enzymatic hydrolysis of the solid residue. This study shows that SUPRADES pretreatment represents a promising and eco-friendly strategy for integrated biorefining by simultaneously optimizing lignin extraction and cellulose digestibility.