Structural properties and sustained antimicrobial activity of thymol-loaded cellulose nanofibers from one-pot synthesis via in situ dynamic microfluidization

The physicochemical properties of cellulose nanofibers (CNFs) are significantly influenced by their production methods and surface modifications. This study presents an eco-friendly approach for synthesizing CNFs impregnated with thymol via a single-step in-situ dynamic high-pressure microfluidization process. Optimal conditions for preserving the intrinsic structure and desirable properties of CNFs were explored using various ethanol-water ratios with thymol. The physicochemical properties and characteristics of CNFs were analyzed using advanced techniques. Thymol-impregnated CNFs at an ethanol-to-water ratio of 10:90 (E10W90) demonstrated a sustained cumulative release of up to 27.5 % over 50 h and complete inhibition of bacterial growth within 3 h against S. aureus and E. coli. Density functional theory analysis indicated that thymol adsorption onto the CNF surface is facilitated by hydrogen bonding. This investigation proposes a novel, energyefficient method for thymol impregnation, achieving prolonged antimicrobial activity without complex surface modifications.