Synthesis, characterization and antibacterial studies of polyvinyl alcohol (PVA)–zinc sulfide (ZnS) thin films for its application in packaging material

Polyvinyl alcohol (PVA) thin films though excellent packaging material does not show any antibacterial activity, and hence reduces shelf life of food, thus effort to increase its activity against bacteria is a need of time. The current work emphasizes the preparation of undoped and co-doped zinc sulfide (ZnS) nanoparticle (NPs) embedded in PVA thin films were prepared by chemical precipitation and microwave method with concentrations of 0.1, 0.2, and 0.3% of ZnS NPs. PVA was used as a capping agent. The NPs synthesized were analyzed by XRD, SEM–EDS, UV–Visible, and FTIR techniques. XRD studies revealed the formation of the face-centered cubic (FCC) structure of zinc blende. FTIR represents the characteristic peaks of Zn–S stretching vibrations at 614 cm⁻¹. The morphology was found to be smooth and spherical shape of nanoparticles from SEM. The antimicrobial activity of as synthesized PVA films was investigated against gram-positive bacteria Enterococcus faecalis (MTCC 439) and gram-negative bacteria Escherichia coli (MTCC 1559). The result showed PVA films which did not show any activity can be made to show antibacterial property by incorporation of NPs which can be used as food packaging material.

Graphical abstract

Shows the mechanism of antibacterial action of PVA ZnS thin film