Antimicrobial Activity of Composite Consisting of Cellulose Nanofibers and Silver Nanoparticles

In this work influence of silver (Ag) nanoparticles (NPs) on cellulose nanofibers (CNF) was investigated. Free standing composite films of CNF/ polyvinylalcohol (PVA) - Ag NPs have been synthesized by ex-situ method. Composite films with different Ag NPs content (1%, 10% and 20%) were obtained and characterized by various techniques such as UV-visible absorption spectroscopy, field emission scanning electron microscopy (FESEM), Infrared (IR) spectroscopy and Thermo gravimetric analysis (TGA). A UV-vis absorption spectroscopy study demonstrates that as Ag NPs content increases the optical transparency decreases. The FESEM studies of the composite films revealed the presence of Ag NPs with average size similar to 20 nm. Infrared spectroscopy illustrates that the CNF/PVA and Ag NPs are bound through electrostatic interactions. Comparison of the thermal properties of the CNF/PVA and the CNF/PVA - Ag composite films showed that the thermal stability is improved for the highest Ag content composite films. It is shown that the CNF/PVA - Ag composites have potential antibacterial effects against Gram-positive bacteria (Bacillus subtilis) and Gram-negative bacteria (Escherichia coli).