Bacterial cellulose with microencapsulated antifungal essential oils: A novel double barrier release system

A double barrier release system is designed for herbal essential oils which possess tremendous anti-fungal activity, even against drug-resistant fungi. However, their utilization is limited owing to their sensitivity towards pH, temperature and light. Three essential oils (thymol, eugenol, carvacrol) are microencapsulated in polylactic acid shell with a high encapsulation efficiency of 80% in order to leverage their synergistic anti-fungal activity. These microcapsules are further incorporated in bacterial cellulose - a naturally produced nanofibrous hydrogel. This unique system offers double barrier to the release of oils - the polymeric shell and the nanofibrous matrix. The anti-fungal testing was carried out on model fungus- Candida albicans (cause of common oral, vaginal infections). In vitro transvaginal drug release study was performed to compare release from microcapsules as colloids and the composites, where the later exhibited a controlled release. Mathematical modelling was performed to understand the release, which is governed by matrix swelling, diffusion of oils and erosion of microcapsules. The time-kill curves show that the composites were able to achieve fungicidal endpoint with half the oil dosage as compared to the colloidal microcapsules and were far more effective than commercial antifungal fluconazole.