Modified chitosan micelles improving physical stability, sustained release, and antibacterial activity of fir essential oil: performance optimization and mechanistic insights

To meet consumer demand for the application of natural ingredients such as essential oils in food systems, this study developed a chitosan-g-poly(lactic acid) (CS-g-PLA) micellar system for fir essential oil (FEO) delivery. The research focused on investigating the regulatory effects of PLA side-chain parameters on micellar properties. Results demonstrated that increasing parameters enhanced hydrophobic interactions, forming compact micelles with a minimal particle size (229.7 nm) and critical micelle concentration (0.012 mg/mL). The hydrophobic core enabled efficient FEO loading (30.99%) with stable sustained release. FEO@CS-g-PLA micelles also showed broad-spectrum antimicrobial activity by disrupting cell membranes. Molecular dynamics simulations visualized the self-assembly of CS-g-PLA and the FEO loading process, providing theoretical support for experimental observations. In summary, this work offers microscopic insights into the micellization of modified CS-g-PLA and FEO loading mechanisms, providing a feasible strategy for applying essential oils in food preservation.