Application of Sodium Alginate and Chitosan for Compound Volatile Oils From Rimulus cinnamon and Angelica sinensis: Microcapsules Preparation, Evaluation, Characterization, and in vitro Release Study

Objectives: The objective of this study was to prepare and evaluate the CVOs microcapsules. Materials and Methods: Chitosan (CS) and sodium alginate (SA) were used as composite wall materials to encapsulate CVOs using the complex coagulation method. The microcapsules were characterized by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT‑IR), X‑ray diffraction (XRD), and thermogravimetric (TG). The drug loading (DL%), encapsulation efficiency (EE%), in vitro release behavior, and stability of the microcapsules were studied. Results: DL (%) and EE (%) of microcapsules were 22.60 ± 0.02% and 72.55 ± 0.04%, respectively. SEM showed that microcapsules were spherical and the surface was not smooth, with lump‑like folds, minor dents, and cracks. FT‑IR and XRD confirmed the inclusion of CVOs within microcapsules. TG analyses indicated that the microcapsules possess strong heat resistance. Swelling experiments reflected the response of microcapsules to different pH values. Swelling ratios in acidic, neutral, and alkaline media were 2.47 ± 0.07, 1.75 ± 0.03, and 1.04 ± 0.01, respectively. The in vitro release behavior of the CVOs microcapsules demonstrated a sustained release property. Furthermore, the microcapsules had excellent stability, and the DL was 15.12% after storage at 25°C for 60 days. Conclusion: The CVOs microcapsules prepared by SA and CS not only showed regular appearance, uniform particle size, responsiveness to different pH values, and sustained release properties in vitro but also exhibited good DL performance and stability, which was helpful for further development into the various specific formulation.