Synthesis and characterization of cellulose derivatives for enhanced antimicrobial activity

Abstract

The need for biodegradable materials has driven the exploration of natural and biobased polymers, with cellulose emerging as a promising option due to its abundance and environmental sustainability. However, cellulose lacks inherent antimicrobial activity, prompting researchers to explore various strategies. In this work, the permanent covalent chemical modification of microcrystalline cellulose with 1-methylimidazole is reported to provide cellulose with antimicrobial properties. The modifications were confirmed using solid-state 13C-NMR and Fourier Transform Infrared (FT-IR) spectroscopies. The analysis from 13C-NMR and elemental analysis also confirmed the successful of the chemical modification occurred at C6 after chlorination with an estimated degree of substitution of 17%. The surface charge density of this cellulosic derivative was determined using ζ potential measurements, which confirmed its cationization. The crystalline and thermal properties of the resulting cellulose derivative were evaluated using X-ray diffraction and thermogravimetric analysis (TGA), respectively. Finally, the antimicrobial activity of the obtained cationic cellulose was assessed against both Gram-positive (Staphylococcus epidermidis) and Gram-negative (Pseudomona aeruginosa) bacteria, giving a reduction of > 99.99% and 99.6%, respectively.