Development and characterization of Citrus limon (L.) Osbeck essential oil nanoemulsions: assessment of antibacterial and antifungal activities.

Background and Purpose: Essential oils (EO) have gained significant attention due to their natural antimicrobial and antifungal properties. However, their application is often limited due to poor solubility, volatility, and stability. Nanoemulsions, as advanced delivery systems, can overcome these limitations by enhancing the bioavailability and efficacy of EOs. Lemon EO, known for its broad-spectrum antimicrobial activity, is a promising candidate for nanoemulsion formulation. This study aimed to synthesize and characterize lemon EO nanoemulsions and evaluate their enhanced antimicrobial and antifungal potential, compared to crude oil. Materials and Methods: Lemon EO was first analyzed using gas chromatography-mass spectrometry (GC-MS) to identify its chemical composition. Lemon EO nanoemulsions were prepared using the spontaneous emulsification technique. The physicochemical properties, including particle size, polydispersity index (PDI), zeta potential, and stability, were characterized using dynamic light scattering. The antimicrobial and antifungal activities were assessed against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Candida albicans, and Aspergillus fumigatus through minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) assays. Results: The GC-MS analysis revealed the major chemical components of lemon EO, including limonene, β-pinene, and γ-terpinene. The nanoemulsions exhibited a mean particle size of about 15 nm, a low PDI (< 0.3), and a negative zeta potential, indicating high stability and homogeneity. The antimicrobial and antifungal activities of the nanoemulsions were significantly enhanced compared to the crude lemon EO, as demonstrated by lower MIC and MFC values. The nanoemulsions also showed excellent stability under various storage conditions. Conclusion: This study demonstrated that lemon EO nanoemulsions are a stable delivery system with superior antimicrobial and antifungal properties. The GC-MS analysis provided valuable insights into the chemical composition of the EO, further supporting its efficacy. These findings suggest the potential of lemon EO nanoemulsions as a natural alternative for applications in food preservation, pharmaceuticals, and cosmetics.