Synthesis of Antimicrobial Films Based on Low-Density Polyethylene (LDPE) and Zeolite A Containing Silver

Abstract

The present study aimed at the preparation of antimicrobial films based on low-density polyethylene (LDPE), with zeolite exchanged with Silver (Ag) in 1, 5 and 10 wt.%. Zeolites with Ag were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray Fluorescence (XRF). LDPE films with added silver-substituted zeolite A were synthesized by wet-casting, with the zeolite content in the films ranging from 1–5 wt.%. The antibacterial activity of the silver-substituted zeolite was assessed according to its minimum inhibitory concentration (MIC), using Escherischia coli as the target bacteria. LDPE films with silver-loaded zeolite were also tested against E. coli and Staphylococcus aureus. Silver insertion in the zeolite did not change its structure. The MIC of the zeolite with 1% silver and a concentration of 0.05 mg zeolite/mL was not able to inhibit the visible growth of the bacteria; however, an increased silver concentration resulted in total inhibition after 24 h of incubation. Zeolites with 5% and 10% of silver showed a MIC of 0.05 mg zeolite/mL. The films with best antibacterial activity against E. coli and S. aureus were those prepared with 5 wt.% zeolites loaded with 5% and 10% of silver. LDPE films with silver-loaded zeolite A are potential resources in the development of active packaging for food preservation and safety.