Fabrication, Characterization, and Transcriptomic Analysis of Oregano Essential Oil Liposomes for Enhanced Antibacterial Activity and Sustained Release

This study prepared oregano essential oil-loaded liposomes (OEO-Lip) and systematically evaluated their physicochemical properties, stability, and antioxidant/antibacterial activities, along with the underlying mechanisms. Characterization revealed OEO-Lip exhibited a unilamellar vesicle structure with a particle size of approximately 190 nm, uniform dispersion (PDI = 0.183), a high zeta potential (-39.8 mV), and an encapsulation efficiency of 77.52%. Analyses by FT-IR, XRD, and DSC confirmed the successful encapsulation of OEO within the liposomes. Hydrogen bonding interactions with phospholipid components promoted the formation of a more ordered crystalline structure, thereby enhancing thermal stability. Storage stability tests demonstrated that OEO-Lip stored at 4 °C for 30 days exhibited significantly superior physicochemical properties compared to samples stored at 25 °C. Furthermore, liposomal encapsulation effectively preserved the antioxidant activity of OEO. Antimicrobial studies revealed that OEO-Lip exerted stronger and more sustained inhibitory effects against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> than free OEO, primarily by disrupting bacterial membrane integrity and inducing the leakage of ions and intracellular contents. Transcriptomic analysis further indicated that OEO-Lip exerts synergistic antibacterial effects by downregulating genes associated with phospholipid synthesis and nutrient transport while concurrently interfering with multiple pathways, including quorum sensing and energy metabolism. Release experiments indicated that OEO-Lip displays both burst and sustained release characteristics. In summary, OEO-Lip serves as an efficient delivery system that significantly enhances the stability and antibacterial efficacy of OEO, demonstrating considerable potential for application in food preservation.