Incorporation of thyme essential oil into the beta-cyclodextrin nanosponges: Preparation, characterization and antibacterial activity

Abstract

Thyme essential oil (TEO) is a natural phenolic compound and has high antimicrobial and antioxidant activity. However, essential oils are very sensitive to environmental conditions and have high volatility and poor solubility that limit their applications. In this study, the incorporation of TEO into the beta-cyclodextrin nanosponges was investigated. Diphenyl carbonate was used as cross-linker. The characterization of the obtained nanosponges was done by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analyzer(TGA). Encapsulation efficiency, loading capacity, solubility, and antibacterial properties of the TEO-nanosponges were analyzed. The TEO-nanosponges showed porous structures with an average size lower than 326 nm. The results of FTIR and XRD confirmed the incorporation of TEO into the nanosponges. Thermogravimetric analysis indicated that the inclusion complex of TEO and nanosponges enhanced the thermal stability of TEO significantly. The inclusion complex of TEO into the nanosponges increased its antibacterial activity. The aqueous solubility of TEO was enhanced by 15-folds after encapsulation within nanosponges. Minimum inhibitory concentration of TEO was decreased up to 29.4 folds after encapsulation into the nanosponges. The results suggest that beta-cyclodextrin nanosponges can potentially be used as a delivery system for hydrophobic and sensitive compounds to increase their usage in the pharmaceutical and food industries. (C) 2021 Elsevier B.V. All rights reserved.