Design and theoretical calculation of chitosan derivatives: Amphiphilic chitosan micelles loaded with Chinese fir essential oil

The unique structure of chitosan-based micelles can be loaded with essential oil, so it is significant to study the modification of chitosan and the interactions between chitosan and essential oil, while molecular dynamics (MD) simulation and density functional theory (DFT) provide a solution. In this study, three kinds of amphiphilic chitosan derivatives (CSDs) were constructed by grafting of different hydrophilic and hydrophobic groups. Amphiphilic chitosan micelles loaded with Chinese fir essential oil (CFEO) were prepared by self-assembly. The aggregation behavior of CFEO component (cedrol and alpha-cedrene) in the solutions of chitosan and three CSDs were simulated using MD, and the mean square displacement was calculated. DFT analyzed the mechanism for regulating the molecular properties of CSDs by different modification methods, and explored the intensity and type of interaction force between cedrol/alpha-cedrene and three CSDs. The results show that cedrol and alpha-cedrene were more easily aggregated near the modified CSDs, with CS-g-PLA showing the strongest trapping ability. The grafting of polylactic acid on chitosan resulted in a significant decrease in HOMO-LUMO energy gap and an increase in reactivity activity. Widely distributed hydrogen bonding and van der Waals forces were confirmed to be the key to enhanced loading capacity.