Preparation and Characterization of Chitosan–Alginate Polyelectrolyte Complexes Loaded with Antibacterial Thyme Oil Nanoemulsions

Abstract

Biomedical industries are attempting to utilize natural materials, as they are bio-compatible, non-toxic, and show bioactive properties, like antimicrobial activity. In this study, natural polyelectrolyte complexed chitosan/alginate films (PECs) were prepared via a casting/solvent evaporation technique, and their characteristics and drug release properties were investigated. PEC films made with two different overall polymer contents, 0.4 and 1 w/v%, were loaded with thyme oil nanoemulsion as drug carrier. The structure of the films was studied by FTIR and optical and scanning electron microscopy. Prepared PEC films had good mechanical and water vapor permeability properties. Release of the thyme oil from the pH-sensitive PEC films (TM-PEC) was detected and followed by UV spectroscopy. The results indicated that the drug release rate of TM-PEC films was the fastest when the chitosan content was 1 %w/v, and various mathematical models were analyzed for investigating the drug release mechanism. Antibacterial tests were performed by counting the number of surviving gram-negative and gram-positive bacteria. The in vitro test indicated the limitation Escherichia coli (E. coli) and Staphylococcus aureus (S.aureus) growth in the presence of TM-PEC films. The MTT test showed more cell viability of the TM-PEC film in comparison with that of the PEC film without TM. Based on the measured physical and antibacterial properties, the chitosan–alginate PEC films loaded with antibacterial essential oils can be considered for biomedical applications, such as wound dressings or controlled release systems.

Development and Characterization of Pequi Oil (Caryocar coriaceum wittm.) Microparticles by Vibration Nozzle Encapsulation

“…Particles are formed by enveloping the negatively charged calcium alginate complex in the pre-gel state with chitosan, and the pre-gel state is essential to enable the ionic interactions between alginate-chitosan. [24] According to Hamedi (2019), [25] a scheme of the alginate-chitosan interaction can be seen in Figure 1.…”

“…The alginate and chitosan spectra are described in the literature highlighting the functional groups identified in this work. [23,25] The specific interactions formed in the Calcium (Ca)-alginatechitosan matrix pequi oil microspheres may be observed in Figure 3. The alginate carboxylic group interacts with the chitosan amine and calcium to form a polyelectrolytic complex.…”

“…As a result, changes occur in the absorption ranges of amino groups, carboxylic acids and amide bonds, as well as the presence of characteristic bands of the encapsulated and bioactive polymers. [25,32] The band related to stretching vibrations of OH and NH bonds in Ca-alginate-chitosan and Ca-alginate-chitosan-pequi oil microspheres were both dislocated for lower wavenumber in comparison to pure biopolymers (Figure 3), indicating intermolecular hydrogen bonds. [22] For the microspheres formed only by Ca-alginate-chitosan, a shift of the asymmetric stretching C═O group was observed in the alginate spectrum at 1614 cm −1 to 1641 cm −1 , and the symmetric stretching C═O group also shifted from 1419 to 1454 cm −1 .…”

“…[22,35] When compared to pure biopolymers (Figure 3), changes in the absorption indicate electrostatic interaction in the Ca-alginate-chitosan complex. [23,25,32] The interaction between the biopolymers will enable the microspheres to present greater resistance and a controlled release in more specific media such as the stomach and intestine. [22,23,25,36] The microsphere spectrum formed by Ca-alginate-chitosanpequi oil has characteristic bands for pequi oil and alginate; asymmetrical and symmetrical C─H stretching intense in CH 2 (2920 and 2853 cm −1 , respectively) and C═O stretching (1746 cm −1 ), both characteristic of pequi oil; and symmetrical C═O stretching (1419 cm −1 ) in alginate.…”

Effect of clinoptilolite on structure and drug release behavior of chitosan/thyme oil γ‐Cyclodextrin inclusion compound hydrogels

“…It has excellent biocompatibility, cell-adhesive properties, and immune-stimulatory activities. [5][6][7] Studies regarding cytocompatibility of chitosan showed that it does not have acute cytotoxic effects. 8 Thyme is an aromatic and medicinal plant with representative species of Thymus serpyllum and Thymus vulgaris.…”