Encapsulation of curcumin in groundnut oil-in-water (O/W) nanoemulsions: Experimental analysis and molecular dynamics simulations

This study presents a comprehensive experimental and molecular simulation investigation aimed at developing highly stable and concentrated oil-in-water (O/W) nanoemulsions for curcumin encapsulation, using Tween 80 and Span 80 as emulsifiers. Experimentally, the influence of oil phase concentration (10-30 wt%) on key physicochemical parameters, including droplet size, polydispersity index (PDI), encapsulation efficiency, antioxidant activity, morphology, and long-term stability, was systematically investigated. All formulations exhibited excellent kinetic and oxidative stability during one month of storage, showing no significant changes in droplet size, size distribution, creaming index, or morphology. The encapsulation efficiency and antioxidant activity of curcumin remained consistently high and stable throughout the storage period. Complementing the experimental work, molecular dynamics (MD) simulations were conducted to elucidate the interactions of curcumin with fatty acids in the oil phase and with emulsifiers, thereby providing molecular-level insights into the nanoemulsion system's structural organization and dynamic behavior. MD simulations confirmed strong molecular interactions between curcumin, oil components, and surfactants, validating the complete encapsulation of curcumin within the oil phase. Quantitative analyses of interaction energy, radius of gyration, and end-to-end distance further elucidated the stabilization mechanism and the cluster-formation behavior of curcumin in the emulsified system. Overall, the formulated emulsions demonstrated outstanding stability and bioactive retention, positioning them as highly effective carriers for curcumin delivery. These findings not only highlight the potential of the developed nanoemulsions for food and pharmaceutical applications but also provide critical molecular-level insights into their stabilization mechanisms, laying a strategic foundation for the design of next-generation functional delivery systems.