Carrageenan-based hydrogels and films: Effect of ZnO and CuO nanoparticles on the physical, mechanical, and antimicrobial properties

Carrageenan-based functional hydrogels and dry films were prepared by blending with metallic nano particles such as zinc oxide (ZnO), copper oxide (CuO) NPs, and their combination. Addition of KCI as a cross-linking agent increased the gel strength of carrageenan-based hydrogels. The neat carrageenan hydrogels were transparent, but they became translucent when the metallic nanoparticles were incorporated. Dried hydrogel films were flexible and free-standing. Transmission of UV light of the carrageenan-based films decreased remarkably when metallic NPs were incorporated. The swelling ratio (SR) of carrageenan films with or without cross-linker were 2980% and 2665%, respectively, however, it increased up to 3535% when ZnONPs were incorporated. The carrageenan-based hydrogel films with metallic nanoparticles exhibited strong antibacterial activity against food-bourne pathogenic bacteria, Escherichia coil, and Listeria monocytogenes. The ZnONPs incorporated hydrogel films exhibited higher mechanical, UV-screening, water holding, thermal stability, and antimicrobial properties than the CuONPs incorporated ones. The nanocomposite hydrogels or films have a high potential for the application in the biomedical, cosmetic, and active food packaging areas. (C) 2017 Elsevier Ltd. All rights reserved.