Evaluation of the antibacterial activity of cellulose nanofibers/polylactic acid composites coated with ethanolic extract of propolis

This work has focused on developing cellulose nanofibers (CNFs)/polylactic acid (PLA) coated with ethanolic extract of propolis (EEP). First, the chemical composition of EEP was studied in order to determine the major compounds. Composites were then prepared using solvent casting method, with the goal of making green composites. The effectiveness of EEP was evaluated for its antibacterial and antifungal properties, using standard protocol of disc diffusion method (DDM). Chemical analysis of EEP indicated that the propolis samples had high concentrations of the aromatic acids, phenolics, esters, and other derivatives, which are responsible for the antibacterial and antifungal properties of propolis. Experimental results indicated that EEP had a considerable antibacterial activity against most of tested pathogen strains. In general, the surface of modified CNFs/PLA films showed antibacterial activity against Gram‐positive bacteria, even at very low concentrations of EEP. The addition of EEP to the tested films drastically increased the antibacterial effect against Gram‐positive, such as Bacillus anthracis, Staphylococcus aureus, and Salmonella enteric, while there was no effect on Gram‐negative bacteria. Moreover, the results pointed out the inhibitory action of EEP on Candida albicans. POLYM. COMPOS., 38:13–19, 2017. © 2015 Society of Plastics Engineers