Preparation and characterization of carrageenan-based nanocomposite films reinforced with clay mineral and silver nanoparticles

Antimicrobial bionanocomposite films were prepared with κ-carrageenan and silver nanoparticles (AgNPs) and organically modified clay mineral (Cloisite® 30B). AgNP-included nanocomposite films showed characteristic plasmonic effect of the AgNPs with the maximum absorption at 420 nm and they also showed high UV barrier properties. Depending on the type of nanofillers, tensile strength (TS) of the nanocomposite films increased by 14–26% and water vapor permeability (WVP) decreased by 12–27% compared to those of the neat carrageenan film. The nanocomposite films exhibited characteristic antimicrobial activity against Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) pathogenic bacteria. While AgNP-included nanocomposite film showed strong antimicrobial activity against Gram-negative bacteria, the clay-included nanocomposite films showed strong antimicrobial activity against Gram-positive bacteria. On the contrary, the nanocomposite film with combined use of both nanofillers showed strong antimicrobial activity against both Gram-positive and Gram-negative bacteria.