Abstract

This work presents the preparation of cellulose nanocrystals (CNCs) from sugarcane bagasse via acid hydrolysis of bleached pulp. Crystallinity and size of CNCs were characterized by XRD and zetasizer at 77% and 260 nm, respectively. CNCs were graft copolymerized in an aqueous suspension by a redox-initiated free radical method using cerium ammonium nitrate (CAN) as the initiator. Glycidyl methacrylate (GMA) was grafted onto CNCs to improve its physicochemical properties and biological activity. The parameters affecting the grafting of CNCs-g-GMA, e.g., GMA and CAN concentrations and grafting time were studied. The results revealed that high grafting yield (~180%) was obtained by increasing GMA and middle concentration of the CAN initiator (2 mmol/g). The grafting yield (%) of CNCs-g-GMA for all grafting conditions was calculated gravimetrically, while CNCs-g-GMA was characterized by FTIR, scanning electron microscope, and thermal gravimetric analysis analyses. Antimicrobial activity of CNCs and CNCs-g-GMA was assessed in vitro against human Gram +ve and −ve bacteria and against Candida albicans fungus. 2.5 g l−1 of CNCs-g-GMA copolymer showed the highest antimicrobial activity, due to its significant ability to kill ~80% of Staphylococcus aureus, 71.4% of Salmonella typhimurium, and 70% of Klebsiella pneumonia. Also, CNCs and CNCs-g-GMA exhibited clinically accepted cell viability (%) with almost 90%–100% versus HDF and WI38 human normal cell lines.

Key words: Cellulose nanocrystals; Extraction; CNC-g-GMA; In vitro bioevaluation tests.