## 1 Introduction  
The neutralization and bridging produced by electrostatic forces is the major mechanism for the formation of polyanion-polycation polyelectrolyte complexes (PEC). There are several factors that affect PEC formation, such as degree of ionization or charge density, position of ionic groups on the polyionic chains, concentration, molecular weight, composition, and mixing order. PH and temperature of the medium are also important [1]. PECs have unique physicochemical properties, which are different from those of their individual components, with a wide range of applications as membranes [2; 3], scaffolds [4; 5], fibers [6; 7], and microcapsules [1; 8]. Alginate and chitosan are interesting biopolymers because they are cheap and well tolerated by the immune system [9; 10]. Their use in PECs is widely reported [11; 12; 13]. Moreover, alginate-chitosan PECs have an impressive effect of limiting the release of encapsulated materials compared to either charged polymer alone [11]. Alginate is derived from seaweed and is an anionic block copolymer of \(\alpha\)-(1-4)-L-gluturonic (G) and \(\beta\)-(1-4)-D-mannuronic acid (M), which is usually present as the sodium salt. Alginate, an acidic linear polysaccharide, is chemically stable at pH values between 5 and 10. It can be converted into a hydrophilic gel which provides a moist wound environment and promotes healing process and epidermal regeneration [2]. The generic term \"chitosan\", which is the deacetylated form of chitin, describes a range of presumably pure poly-(beta-1-4) N-acetyl-D-glucosamine materials. Chitosan is synthesized by various number of living organisms, such as insect cuticles and crustacean skeletons, e.g., crab, shrimp and lobster, and fungi [12]. Chitosan with excellent cell-adhesive properties and bacteriostatic effects can accelerate wound healing process [13]. Chitosan and alginate polysaccharides are both biocompatible and nontoxic materials (Figure 1), so their PEC films are non-cytotoxic towards human fibroblasts. [PERSON] et al. [14] showed that human fibroblast cells on the PEC of sodium alginate and Chitosan retained more than 91% viability over a 4-day period of exposure. Chitosan-alginate membranes have been studied for low molecular weight drug delivery in a wound dressing. A 1:1 ratio of chitosan and alginate gives the greatest viscosity and a high porosity structure, and because of the complete pairing effect of ionic materials, less functional groups are accessible for reacting with drugs [15]. Because of the high antimicrobial, antioxidant, and antifungal activities of essential oils, their use in different fields, like the food, cosmetic, and pharmaceutical industries, has been increasing recently [16]. Thyme oil extracted from _Thymus vulgaris_ has shown inhibitory activities against different bacteria and yeasts [17; 18]. The major constituents of thyme essential oil, which is rich in phenolic phytochemicals, have been reported to be thymol, carvacrol, and \(\gamma\)-terpinene [19; 20]. Antimicrobial activity of twenty plant oils and extracts against _Candida albicans_ (_C. albicans_), _Staphylococcus aureus_ (_S. aureus_) and _Escherichia coli_ (_E. coli_) was investigated by [PERSON] et al. [21]. The lowest minimum inhibitory concentration was obtained 0.03% (v/v) for thymol against _C. albicans_ and _E. coli_. In a case study done by [PERSON] et al. [22], different topical pharmaceutical products marketed in Belgium containing fragrances were tested on 18,960 patients to investigate their allergic contact effects. In this study, products with thyme oil or thymol showed the lowest allergic effects, which is also confirmed by [PERSON] [23]. Encapsulation of essential oils in nanoemulsions has proved a new strategy for improving their efficacy, stability, and utilization [24]. Nanoemulsions are categorized as nanosized delivery systems for lipophilic compounds, such as flavors [25], vitamins [26], and antimicrobials [27].