Antibacterial studies of vitamin E encapsulated lemongrass oil nanoemulsions against gram-negative and gram-positive bacteria

Abstract

The current study assessed the antibacterial properties of vitamin E nanoemulsions, synthesized using a low-energy phase inversion emulsification method. The nanoemulsions were characterized through particle size analysis, and their antimicrobial efficacy was assessed against the bacteria Staphylococcus aureus and Escherichia coli by disc diffusion method. The mechanisms underlying the antibacterial activity were investigated through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The vitamin E nanoemulsions demonstrated significant antibacterial activity against both bacterial strains. Specifically, the zone inhibition diameters for S. aureus and E. coli increased by 5.68 times and 2.61 times, respectively, compared to the pure vitamin E component. The incorporation of Tween 80 as a surfactant resulted in a reduction of the antibacterial properties of the nanoemulsions. Furthermore, the study found that the vitamin E encapsulated lemongrass oil nanoemulsion demonstrated higher antibacterial activity to S. aureus and E. coli when compared to other nanoemulsions. The nanoemulsions exhibited significantly greater resistance to S. Aureus as compared to E. coli. SEM and FTIR analyses revealed that the nanoemulsions induced alterations in bacterial cell membrane permeability and surface characteristics. These results confirmed the mechanism of vitamin E nanoemulsions antibacterial activity and established a crucial base for their potential use in food matrices. © 2025 Canadian Society for Chemical Engineering.