# Electrospinning of Essential Oils
## 3 Electrospun Fibres Containing EOs and Their Applications
### Cinnamon Essential Oil  
Cinnamon EO is extracted from the leaves and bark of ever green aromatic trees of the _Cinnamomum_ genus and _Lauraceae_ family, and distributed in China, India, America, and Australia [70]. Its main chemical component is cinnaldehyde, which is active against pathogens such as _Escherichia coli_ (_E. coli_), _Staphylococcus aureus_ (_S. aureus_), _Porphylromonas gingivalis_ (_P. gingivalis_), _Listeria monocytogenes_ (_L. monocytogenes_), and _Bacillus cereus_ (_B. cereus_) [71; 72; 73; 74]. It has been demonstrated that cinnamon EO induces permanent damages to the morphology and permeability of the cytoplasmic membrane of _E. coli_ and _S. aureus_, when the bacteria are exposed to EO doses in the range of 1-4 mg/mL [71; 72]. The disruption of the membrane integrity causes leakage of nucleic acids and proteins, with consequent bacteria death. This phenomenon is more evident for _S. aureus_ (Gram-positive bacterium), whose membrane is less resistant to hydrophobic molecules (such as EOs), than for _E. coli_ (Gram-negative bacterium). Increased cell membrane permeability, loss of DNA, RNA and proteins, deformation and rupture of cells have been recorded also for _P. gingivalis_ (a Gram-negative anaerobic bacterium responsible for chronic periodontitis) treated with cinnamon EO (dose of 6.25 mg/mL) [73]. Cinnamon EO has been electrospun in combination with a range of polymers, including polyvinyl alcohol (PVA) [39; 40], alginate/PVA [41], polylactic acid (PLA) [42], poly(ethylene oxide) (PEO) [43], and cellulose acetate [44], and the resulting fibres have been applied to food and biomedical sectors. In most works, complexes of cinnamon EO and cyclodext were processed. Cyclodext are natural cyclic oligosaccharides with a truncated cone shape characterised by a hydrophilic external surface and a hydrophobic interior cavity (Figure 2a) [26; 75; 76]. They are extensively used to form inclusion complexes with essential oils, which are trapped in the hydrophobic cavity, in order to improve EOs bioavailability and stability. Antimicrobial and biodegradable packaging materials have been produced by incorporating cinnamon EO and \(\beta\)-cyclodextrintrim (\(\beta\)-CD) into PVA [39], PLA [42], and PEO [43] nanofibers. [PERSON] and collaborators reported on PVA solutions prepared by dissolving PVA in water at a 6% w/w concentration and adding 2% w/w of cinnamon EO and 2% w/w of \(\beta\)-CD [39]. The electrospinning process was conducted with a voltage of 15 kV, a flow rate of 0.5 mL/h and a needle-collector distance of 15 cm to achieve an average fibre diameter of (300 \(\pm\) 60) nm. The antimicrobial activity of cinnamon EO was tested against _E. coli_ and _S. aureus_. The electrospun PVA/EO/\(\beta\)-CD matsgenerated inhibition zones of (\(28.9\pm 0.3\)) mm for _E. coli_ and (\(30.5\pm 0.4\)) mm for _S. aureus_, and were slightly more effective than 50 ug/disk of the antibiotic kanamycin sulphate [(28.2 \(\pm\) 0.2) mm for _E. coli_ and (\(24.1\pm 0.5\)) mm for _S. aureus_]. MIC values (minimum concentration of fibres to inhibit the microorganisms growth) of 1.0 mg/mL for _E. coli_ and 0.9 mg/mL for _S. aureus_ were recorded, corresponding to 9-10 ug/mL of cinnamon EO (4-5 ug/mL of kanamycin sulphate were needed to achieve the same effect); whereas, MBC values (lowest concentration of fibres to kill 99.99% of microorganisms after 24 h of incubation) were of 8.0 mg/mL for _E. coli_ and 7.0 mg/mL for _S. aureus_, corresponding to 70-80 ug/mL of cinnamon EO (effective as 15-20 ug/mL of kanamycin sulphate). Cinnamon EO not only stopped the growth of microorganisms but also increased the shelf-life of packed strawberries. When the electrospun PVA/EO/\(\beta\)-CD mats were applied as food packaging material (at 4 \({}^{\circ}\)C), the firmness of the fruit (one indicators of freshness) decreased by only 14% after 18 days of storage; while a decrease of 35% was recorded when a commercial fresh-keeping film was used instead of the electrospun mat.