Antibacterial activity study of ZnO incorporated biodegradable poly (lactic acid) films for food packaging applications

In this report, the antibacterial activity of pure polylactic acid (PLA), Zinc oxide (ZnO) incorporated PLA, and ZnO nanorods grown on the ZnO incorporated PLA films prepared by a simple film casting method was studied. ZnO nanorods were grown on ZnO mixed PLA films by a simple hydrothermal method at 80 degrees C temperature. The SEM study confirms the formation of ZnO nanorods on PLA. The length and diameter of nanorods are approximately 2-3 mu m and 500 nm, respectively. The high elemental percentage of Zn and O was observed in the energy-dispersive spectra of ZnO nanorods grown ZnO mixed PLA film due to the presence of ZnO nanorods on the surface of the film. The TGA analysis has shown thermal stability enhancement by approximately 10 degrees C in the ZnO nanorods grown film compared to pure PLA film. Furthermore, the antibacterial activity of these films was tested against Escherichia coli (E. coli) bacteria and Staphylococcus aureus (S. aureus) bacteria. The zone of inhibition values for pure PLA, ZnO incorporated PLA, and ZnO nanorods grown films are 0, 16, 19 mm and 0, 18, 21 mm for E. coli and S. aureus, respectively. More antibacterial activity was observed for the film containing ZnO nanorods on its surface than the pure PLA and ZnO mixed PLA films. This process of growing ZnO nanorods on PLA film surfaces can be easily adapted to large-scale production for packaging applications.