Silver ion loaded 3-aminopropyl trimethoxysilane -modified Fe3O4 nanoparticles for the fabrication of carrageenan-based active packaging films.

Fe3O4 nanoparticle loaded with silver ion was prepared as a more efficient, safer, and less environmentally hazardous silver-based antibacterial nanomaterial. The Fe3O4 nanoparticle was modified using 3-aminopropyl trimethoxysilane (APTMS) to enhance the silver ion adsorption capacity and antibacterial activity. Silver ions were adsorbed on pristine Fe3O4 and Fe3O4@NH2 to enhance antibacterial activity. Energy dispersive spectroscopy (EDS) results showed that Fe3O4 adsorbed 2.74 wt% of Ag, whereas Fe3O4@NH2 adsorbed 9.88 wt%. Pristine Fe3O4NP, silver ion loaded Fe3O4 (Fe3O4-Ag), and silver ion loaded Fe3O4@NH2 (Fe3O4@NH2-Ag) were used to manufacture carrageenan-based composite films. Compared with Fe3O4-Ag, Fe3O4@NH2-Ag exhibited stronger antimicrobial activity against E. coli (8.82 vs. 5.02 log reduction) and L. monocytogenes (10.09 vs. 3.93 log reduction). While the addition of Fe3O4 significantly reduced the WCA of the carrageenan films from 61.1 ± 5.4 ° to 37.2 ± 2.1 °, the additions of Fe3O4-Ag and Fe3O4@NH2-Ag reduced the WCA of the film to a lesser extent (56.9 ± 4.6 ° and 56.9 ± 4.6 °, respectively). Fe3O4NP also improved the thermal stability of carrageenan over Fe3O4@NH2-Ag (22 °C vs. 13 °C) and UV blocking properties (T280, 0.1 ± 0.0 % vs. 3.3 ± 1.5 %).