Supramolecular\nRegulation and Controllable Coproduction\nof Bamboo Nanocellulose and Mono/Oligosaccharides via Dual-Enzymatic\nTreatment Assisted by Ball Milling

Nanocellulose\n(NC) derived from lignocellulosic biomass has served\nas a promising material for functional applications. However, conventional\nchemical and mechanical processes for NC fabrication are environmentally\nharmful and energy intensive and may inevitably cause component loss.\nHerein, a green dual-enzymatic treatment assisted by ball milling\nstrategy was proposed for bamboo pulp to produce NC with varied morphologies\nand supramolecular structures, as well as the coproduction of monosaccharides\nand xylooligosaccharides (XOS) with reduced enzyme loading and treatment\ntime. Endoglucanase (EG) and xylanase at various loading ratios were\nused for adjusting the physical–chemical structures of NC.\nMechanistic studies showed the accomplishment of nanofibrillation\nunder shorter ball milling time via retention of hemicelluloses, while\nlonger ball milling time intensified fibril deconstruction, thus exposing\ncellulose hydrophobic surfaces favorable for subsequent enzymatic\nhydrolysis. The method was subsequently applied to bamboo holocellulose\nand microcrystalline cellulose (MCC)/xylan models, which obtained\nthe highest yields of 23.2% glucose, 24.4% XOS, and 21.5% NC. Bamboo\nholocellulose produced NC with a high aspect ratio of up to 55.1,\nwhile MCC produced spherical NC with cellulose II allomorph. The proposed\nball-milling-assisted dual-enzymatic treatment can provide theoretical\nguidance for high-value conversion and more complete utilization of\nbamboo polysaccharides.