Ultrasonication-Enhanced Nanoencapsulation of Thymol and Cinnamaldehyde with Chitosan and Hydroxypropyl Methylcellulose: A Novel Approach to Improving Physicochemical Properties, Stability, and Bioactive Content

This study presents a novel approach to enhancing the physicochemical properties, stability, and bioactive content of thymol and cinnamaldehyde-loaded nanocapsules (NCs) using chitosan (CH) and hydroxypropyl methylcellulose (H) as wall materials, optimized via ultrasonication at varying powers (200, 400, and 600 Watts). The results demonstrated that increasing ultrasonic power significantly improved the performance of NC-CH formulations. The NC-CH-400 formulation achieved optimal values in particle size (286.47 ± 19.11 nm), polydispersity index (0.24 ± 0.18), and ζ-potential (5.37 ± 0.24), while the NC-CH-600 formulation exhibited superior nanocapsule’s efficiency (97.8%), antioxidant activity (28.4%), antioxidant capacity (4.76 mg TE ml ^− 1 ), and other physical properties, including enhanced hygroscopicity, density, flowability, and porosity. Additionally, NC-CH-400 displayed the highest solubility (42.33%) and lowest water activity (0.45). Incorporating H with CH further improved nanocapsule’s yield (83.57%) and wettability (4.62 s) over CH alone. FTIR analysis confirmed successful nanocapsule without chemical modification, and the NC-CH-400 formulation showed the highest thermal stability, evidenced by the maximum glass transition temperature and melting points, suggesting superior storage durability. The nanocapsules also exhibited a smooth microstructure without surface cracking, and after 28 days, formulations treated with higher ultrasonic powers significantly enhanced the release of bioactive compounds, particularly in NC-CH. These findings underscore the potential of ultrasonication-enhanced nanocapsule for improving the stability and bioactive delivery of sensitive compounds, offering valuable applications in the food and pharmaceutical industries.