Encapsulation of essential oil in cyclodextrin: An exploration of rational design, molecular interactions, and activity assessment

In this study, coprecipitation (CP) and ultrasound-aided (UA) methods were used to investigate the feasibility of using α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) to encapsulate Ligusticum chuanxiong essential oil (CEO). The physiochemical properties, interaction mechanisms, encapsulation processes, antimicrobial activity and mechanisms of the CEO-loaded CDs were systematically investigated. Experimental results, including FT-IR, Raman, 1 H NMR, SEM and XRD data, indicate the successful CEO encapsulated in CDs. The TGA results show that the CEO-loaded CDs enhanced the thermal stability of the CEO. The CD and CEO interaction mechanism and complexation process were explained from a microscopic viewpoint via molecular docking and molecular dynamics simulations. The results show that hydrogen bonding is the main driving force for the entry of CEO into CDs. β-CD and CEO can form a stable conformation, but α- and γ-CDs exhibit a dynamic process of binding and detaching from the CEO. The results of the antimicrobial mechanism indicated that CEO, α-, β- and γ-CD UAs lead to the inactivation of E. coli and S. aureus by altering the permeability of the biofilm, leading to the leakage of nucleic acids and proteins. Comprehensive studies have revealed that β-CD is a suitable encapsulation material for encapsulating CEO, but α-CD UA exhibits better antimicrobial activity than β- and γ-CD UAs. A combination of experiments and computer simulations can be used for the rational design, optimization and application potential of EO-loaded CDs. This provides new avenues for the practical application of CEO and new insights into the encapsulation of other EOs by CDs or CD derivatives. • The CEO was encapsulated in CDs by coprecipitation and ultrasound-aided methods. • The formation mechanisms were explored by molecular simulations. • The CEO-loaded CDs inactivated the bacteria by leaking proteins and nucleic acids. • Ultrasound-aided method improved encapsulation capacity.