Physical, mechanical, and antibacterial characteristics of bio‐nanocomposite films loaded with Ag‐modified SiO 2 and TiO 2 nanoparticles

In this study, starch‐based films incorporating metal oxide (MO 2 ) nanoparticles (NPs) of TiO 2 and SiO 2 (at a concentration of 1 to 4 wt. %) were produced by solution casting method. In order to exhibit antimicrobial properties, MO 2 NPs were modified by synthesizing silver (Ag) ions over the NPs using cationic adsorption method. Ag ions were then reduced to metallic Ag by sodium borohydride solution. Scanning electron microscopy showed a smooth surface for the pure starch film. Incorporating MO 2 @Ag NPs in the films increased surface roughness with agglomerated NPs within starch matrix. Energy dispersive X‐ray analysis exhibited a uniform dispersion of Ag‐loaded MO 2 NPs, which increases surface contact between these NPs and the biopolymer matrix leading to improved physical and mechanical properties of the resulting films. With increasing in the NPs concentrations, the tensile strength and elongation at break % of the films increased and decreased, respectively. Incorporating MO 2 @Ag NPs into starch matrix decreased solubility in water and water vapor permeability of the obtained films, and significantly inhibited the growth of Escherichia coli and Staphylococcus aureus . The most antibacterial effect was obtained for the films containing higher weight concentrations of Ag‐loaded SiO 2 ‐NPs.