A simple and low-cost strategy to develop antibacterial composite film of nanocellulose and stilbite zeolite...

Herein, we report a detailed preparation method for a low-cost antibacterial film made from sustainable materials- cellulose nanofibers (CNF) and stilbite zeolite using a simple solvent casting technique. The preparation process involved a series of steps: isolation of cellulose from Teff straw, purification and ultra-sonication of cellulose to CNF, purification of stilbite, and the fabrication of CNF/PVA/stilbite composite films. The results indicated that the carefully optimized inclusion and processing of CNF and stilbite particles led to improvements in the mechanical strength, thermal resistance, morphological properties and antibacterial activity of the nanocomposite films when compared to bare PVA film. Besides, the CNF networks maintained homogenous blend of the components and uniformity of the subsequent composite films. Interestingly, the integration of stilbite (STI) into the composite films led to high antibacterial activity against both gram-positive and gram-negative bacterial strains, with clear inhibition zones of up to 12.33 mm for E. coli and 13.30 mm for S. aureus. The activities are higher or comparable to commercial Amoxicillin antibiotics that demonstrated zones of inhibition of 13.0 and 9.8 mm against E. coli and S. aureus, respectively. The unusual antibacterial property of STI particles could be ascribed to the presence of free metal ions in STI that can form metal hydroxides in the interfacial structures between STI particles and CNF/STI polymer networks. The rough morphology of the composite film due to the inorganic clay fillers can contribute to reduce biofilm formation, which is essential in water treatment and other disinfection applications. These low cost cellulose-scaffolded clay composite film hold promise as a well-performing sustainable material alternative for various applications like food packaging, surface disinfection coatings, and water treatment membranes.