Core–shell nanofibers as carrier systems for sustained delivery of tea tree oil

Tea tree ( Melaleuca alternifolia) oil is a plant-derived essential oil with broad-spectrum antimicrobial activity. In this study, tea tree oil, a volatile essential oil, was encapsulated into a polymeric matrix by emulsion electrospinning to prepare core–shell nanofibers and investigate composite nanofibrous membranes as potential delivery vehicles of the antimicrobial agent. Poly(vinyl alcohol) (PVA), which is a biodegradable polymer used as a medical material, was combined with tea tree oil for pharmaceutical and medical applications. Composite PVA nanofibers with a well-aligned core–shell structure containing tea tree oil were obtained via electrospinning from an emulsion comprising the oil and an aqueous PVA solution. Thermal treatment was used to make the PVA-based nanofibrous membranes stable in moist environments. The effects of drying and thermal treatment on the release behavior of tea tree oil from the composite membranes were thoroughly investigated. The antimicrobial effects of tea tree oil embedded in nanofibrous membranes were assessed against Propionibacterium acnes and Staphylococcus aureus. Although the thermal treatment of the PVA nanofibers loaded with tea tree oil reduced the emission of volatile organic compounds, terpinen-4-ol, an active antibacterial component of the oil, was released continuously over 14 days. The composite membranes containing tea tree oil presented strong antibacterial effects against Propionibacterium acnes and Staphylococcus aureus. Thus, these bioactive nanofibrous membranes show promise as potential carrier systems for tea tree oil, which represses microbial growth, and may be used for topical skin infection treatment.