Source-dependent cellulose I and II nanocrystals functionalized with quaternized chitosan for enhanced thermal stability and antibacterial activity

In this study, we extracted cellulose I and II nanocrystals (CNCs) from various agricultural wastes and further modify their surfaces with quaternized chitosan to develop alternative, eco-friendly antibacterial nanomaterials. The CNCs were produced using ultrasound-assisted acid hydrolysis (45 % H₂SO₄, 60°C, 30 min) from diverse cellulose sources, including durian husk, banana pseudostem, bamboo sawdust, corn husk, rice straw, and water hyacinth stem. This ultrasound-assisted method led to a 4–46 % increase in CNC yield compared to the conventional method (without ultrasound). Under identical hydrolysis conditions but with different cellulose sources, CNCs with varying properties were obtained. CNCs from durian husk exhibited the shortest length (∼100 nm) and primarily consisted of cellulose II. In contrast, CNCs derived from banana pseudostem, bamboo sawdust, corn husk, and rice straw displayed relatively longer lengths (∼300 nm) and were predominantly composed of cellulose I. Notably, CNCs from water hyacinth showed a bimodal size distribution and contained a mixture of cellulose I and II. Furthermore, quaternized CNCs were synthesized through surface grafting with quaternized chitosan. These modified CNCs exhibited cationic surface properties, which significantly enhanced their thermal stability and antibacterial performance, demonstrating strong potential for applications in biomedical and advanced materials. • A versatile approach was used to convert various agricultural wastes into high-value cellulose nanocrystals. • The dimensions and crystalline structures of cellulose nanocrystals depended on the cellulose sources • The antibacterial activity of cellulose nanocrystals was enhanced through surface grafting with quaternized chitosan.