Carrageenan-Based Antimicrobial Films Integrated with Sulfur-Coated Iron Oxide Nanoparticles (Fe3O4@SNP)

Recently, antibacterial nanocomposite films containing sulfur nanoparticles (SNPs) have been attracting attention in the food packaging field; however, due to the hydrophobic properties of SNPs, dispersion in hydrophilic biopolymers is nonuniform. Therefore, the functionality of SNPs is not fully utilized. For addressing this, sulfur-coated Fe3O4 hybrid nanoparticles (Fe3O4@SNP) with a core-shell structure were synthesized. Functional nanocomposite films of carrageenan were fabricated by integrating with Fe3O4, SNP, and Fe3O4@SNP nanoparticles, and their properties, including mechanical strength, UV-vis barrier, water vapor permeability (WVP), surface morphology, thermal stability, water contact angle (WCA), surface color, and antibacterial activity, were studied. The Fe3O4@SNP hybrid nanoparticles were dispersed uniformly in the carrageenan matrix. Fe3O4@SNP blocked UV light more effectively (T-280 = 1.3 +/- 0.2%) than SNP (T-280 = 46.5 +/- 0.0%). In addition, Fe3O4@SNP showed stronger antibacterial activity against Escherichia coli and Listeria monocytogenes than SNP. SNP showed 0.63 and 2.87 log CFU/g reduction of E. coli and L. monocytog,cnes, respectively, whereas Fe3O4@SNP exhibited 3.20 and 4.59 log CFU/g.

Automated summary

Antibacterial nanocomposite films containing sulfur nanoparticles have attracted attention in the food packaging field. Hybrid nanoparticles of sulfur-coated Fe3O4 with a core-shell structure were synthesized to improve dispersion in hydrophilic biopolymers and enhance functionality. The nanocomposite films showed improved UV barrier and antibacterial activity compared to films containing only sulfur nanoparticles.