Dextran-coated silver nanoparticles for improved barrier and controlled antimicrobial properties of nanocellulose films used in food packaging

Abstract

The effect of dextran-coated silver nanoparticles (Ag NPs 12.0 ± 1.9 nm) loading (0−0.42 wt%) on the mechanical, barrier, and antimicrobial properties of thin (50−60 μm) films prepared from cellulose nanofibrils by solvent casting method were studied as eco-friendly and food-preservative packaging materials. The presence of dextran was shown to act not only as a dispersing media for Ag NPs and controlling its release but also as a moisture-resistant sealable additive that, synergetically with reduced oxygen permeability, may preserve the food against bacteria growth. Thus, significantly reduced Oxygen Transmission Rates (from 2.07 to 1.40-0.78 cm3 m−2d−1) and hydrophilicity (from 20.8° to 52.4° for MilliQ water, and from 35-37° to 62-74° for 3 % acetic acid and 0.9 % NaCl simulant solutions), yielding a 99.9 % inhibition of Escherichia coli after five repeated cycles of 24 h exposure to 0.9 % NaCl solution was displayed, supported by a controlled release of Ag+ ions (below the toxicologically harmful threshold, <0.5 mg L-1).