Preparation of Antibacterial Dialdehyde Nanocellulose Using LiBr·3H₂O Non-Dissolving Pretreatment Promoted Periodate Oxidation

Dialdehyde nanocellulose (DANC), obtained via periodate oxidation, has been widely used in foods, cosmetics, and biomedical fields due to its unique characteristics. However, the high-crystallinity and tight structure of cellulose retards the efficiency of periodate oxidation for producing DANC. Herein, a novel sustainable and clean approach with less energy consumption and low cost was developed through LiBr·3H₂O (LBTH) non-dissolving pretreatment, which can shorten the oxidation time of the followed periodate oxidation and reduce the oxidant consumption. It was shown that the cellulose Iβ structure of hardwood dissolving pulp (HDP) was largely transformed into an amorphous structure after LBTH non-dissolving pretreatment for 30 min, and the corresponding crystallinity of HDP was reduced from 83.2 to 48.7%. After pretreatment for 60 min, the aldehyde group content of the obtained DANC increased by around 30% compared to the control without pretreatment while the operational cost was reduced by 45%. Moreover, the fabricated DANC showed strong antibacterial activity against both Escherichia coli and Bacillus subtilis. LBTH was recovered and reused, and the pretreatment effectiveness was also maintained. This study provides a sustainable, cost-effective, and clean approach for the preparation of DANC and will promote the application of cellulose nanomaterials.