Microscopical Analysis of Chitosan Patch Functionalized with Clove Essential Oil

Chitosan (Cs) is a biopolymer with good biomedical and biodegradable properties. It is used in different forms, such as films, gels, particles, and wires, to be applied in biomedical applications such as tissue regeneration, antibacterial activity, and material transportation. Nevertheless, the properties of chitosan can be improved with certain materials, such as essential oils [1-4]. The clove (Syzygium aromaticum) essential oil (CEO) is widely used in food presentation, perfumery, and some biomedical applications due to its antimicrobial, antioxidant, and analgesic properties. The functionalization of Cs films with CEO could be applied to wound healing; therefore, this study presents the optical and electron microscopy image analyses of the surfaces and the transverse-section morphology of Cs films functionalized with different quantities of CEO [5-8]. Chitosan films (Csf) were produced using Cs pounder dissolver in a solution of acetic acid in bi-distilled water and triethanolamine (TEA). 0, 3 and 5% v/v of CEO were included in three samples (M0, M3 and M5) that were placed in plastic petri dishes of 5 cm in diameter and dried in an atmospheric drying cabinet for 2 days. To study the liberation process of the CEO of Csf+CEO films, parts of each film were cut and immersed in 20 mL of bi-distilled water at 36 °C under electromagnetic agitation for 30 min. The parts of the M0, M3, and M5 with and without the liberation process were analyzed using a Mitutoyo TM-505B Optical microscope with a 51MP microscope camera in a transition configuration and a Scanning Electron Microscope (SEM) using a CUBE Emcrafts electron microscope. Fig. 1 shows the images obtained using optical microscopy before and after the liberation process. Fig. 1a exhibits the circular pieces of Csf+CEO films with a diameter of 6.5 mm. The M3 and M5 films had greater opacity than the M0 film due to the incorporation of the CEO into the Csf. Fig. 1b presents images of the Csf+CEO films (M0, M3, and M5) obtained before the liberation process, which exhibit a similar morphology with defects (D) and bumps (B). After the liberation process, the defects and bumps in the films disappears, showing pitting (P) and degradation (De) marcs, especially for the M5 sample (Fig. 1c). The elimination of the defects and bumps, and the formation of pitting and degradation marcs were produced by the dilution of the Cs matrix and liberation of the CEO during the liberation process. Fig. 1 shows the SEM images of the M0, M3, and M5 samples before the liberation process. The surfaces of the samples show a similar morphology with homogeneous texture (see Fig. 2a). In the same way, the transversal section of the samples with and without CEO had a similar morphology, with a dense appearance (see Fig. 2b). The similar morphology of the surfaces and transversal sections indicates that the inclusion of CEO does not modified the Csf morphology. The Cfs film thickness was modified by including the CEO, with values of 37.1±0.5 μm for the M0 sample and 137.7±1.7 and 228.5±24.7 μm for the M3 and M5 samples, respectively. Fig. 3 presents the SEM images of the Csf+CEO samples after the liberation process. The M0 sample had a homogeneous surface, with a lamellar transversal section. The M3 sample shows a soft surface morphology and a columnar morphology of the transversal section with high plastic deformation due to the fracture of the sample. In the same way, the M5 sample exhibits a soft texture with bubble (Bl) formation on the surface, and a solid morphology with low plastic deformation of its transversal section. The variation in the surface texture and transversal morphology of the samples produced by the liberation process showed that the inclusion of the CEO improved the cohesion of the Csf films. Optical images of Csf+CEO before (M0=0%, M3=3% and M5=5%) and after (M0a,M3a and M5a) liberation process using optical microscopy at 10X (0.5 mm scale). SEM images of the surfaces and transversal section of the M0, M3 and M5 samples before of liberation process. SEM images of the surfaces and transversal section of the M0, M3 and M5 samples after of liberation process.