# Electrospinning of Essential Oils
## 3 Electrospun Fibres Containing EOs and Their Applications
### Lavender Essential Oil  
_Lavandula_ species are native to the Mediterranean region but largely distributed and cultivated worldwide as aromatic and medicinal plants [101; 102]. The essential oils extracted from _Lavandula__angustifolia_ and _Lavandula latifolia_ are the most appreciated in pharmaceutical, perfume, and cosme industries, aromatherapy and phytotherapy, for their anxiolytic, sedative, anti-inflammatory, antioxidant, and antimicrobial activity [103]. It has been demonstrated that these essential oils and their components impact on the central nervous system and can be used to treat anxiety and reduce stress [102; 103]. The main components of _L. angustifolia_ and _L. latifolia_ EOs are oxygenated monoterpenes: linalool (25-38%), linalyl acetate (25-45%) and lavandulyl acetate (3.4-6.2%) for _L. angustifolia_ EO; linalool (34-50%), 1,8-cineole (16-39%) and camphor (10-20%) for _L. latifolia_ EO [101]. So far, lavender EOs have been encapsulated in electrospun fibres of sodium alginate [62], polyurethane [63], and polyacrylamide[64], to promote wound healing and skin regeneration. Polyurethane (Tecoflex) fibres containing different concentrations of silver nanoparticles (1-7% w/w) and lavender EO (5-20% w/w) have been electrospun at a voltage of 15 kV, flow rate of 0.5 mL/h and needle-to-collector distance of 15 cm [63]. The resulting nanocomposite fibres had a diameter in the range of 0.6-1.0 \(\upmu\)m. The fibres containing 15% and 5% w/w of lavender EO and Ag nanoparticles, respectively, were effective against _E. coli_ (zone of inhibition of \(\sim\)16 mm) and _S. aureus_ (zone of inhibition of \(\sim\)6 mm), as shown in Figure 3b,c. Moreover, biocompatibility tests on chicken embryo fibroblasts suggested that these concentrations of lavender EO and silver nanoparticles enhanced cell proliferation, with a 2.4-fold increase in cell viability (6-day incubation) with respect to the control samples (polyurethane fibres without lavender EO and silver nanoparticles). However, cytotoxic effects were recorded for higher concentrations of lavender EO and silver. Previous studies have reported on the toxicity of lavender EO on human foetal lung fibroblasts (MRC-5) [104], human fibroblasts [105], and L929 fibroblasts [106], when the essential oil has been added to the cell culture medium. IC\({}_{50}\) values of 75 \(\upmu\)g/mL have been reported for MRC-5 cells after 48 h of exposure (IC\({}_{50}\) is the concentration that produces 50% inhibition of cell survival) [104]; while toxic effects have been observed for EO concentrations higher than 12.5 \(\upmu\)g/mL administered to L929 fibroblasts for 48 h [106]. The encapsulation of lavender EO into electrospun fibres limits the potential toxicity of the oil that is released at a slow rate, and therefore allows the use of initial EO concentrations up to 200 \(\upmu\)g/mL [63; 64].  
Figure 3: (**a**) 2,2-Diphenyl-1-picryl-hydraz (DPPH) radical scavenging activity of electrospun  
fibres containing different concentrations (0%, 3%, 6% and 9% v/v) of peppermint EO (PO), chamomile EO (CO) and their blends (PO/CO). (*) p \(<\) 0.05 versus the control group. Inset: Photographs of DPPH solutions containing the different types of mats. Reproduced from Ref. [50], with permission from the American Chemical Society. (**b**) Zones of inhibition of polyurethane (PU) fibres containing different concentrations of lavelander EO (LO) and silver nanoparticles (Ag NPs): sample O: pristine PU fibres; sample A: 5% LO and 1% Ag NPs; sample B: 10% LO and 3% Ag NPs; sample C: 15% LO and 5% Ag NPs; sample D: 20% LO and 7% Ag NPs. Reproduced from Ref. [63] with permission from Elsevier. (**c**,**d**) Photographs of agar plates during disk diffusion assays for _E. coli_ and _S. aureus_, respectively. Reproduced from Ref. [63] with permission from Elsevier.