Thyme/garlic essential oils loaded chitosan–alginate nanocomposite: Characterization and antibacterial activities

Abstract

For controlling pathogenic bacteria using nanopolymer composites with essential oils, the formulation of chitosan/alginate nanocomposites (CS/ALG NCs) loaded with thyme oil, garlic oil, and thyme/garlic oil was investigated. Oils were encapsulated in CS/ALG NCs through oil-in-water emulsification and ionic gelation. The CS/ALG NCs loaded with oils of garlic, thyme, and garlic–thyme complex had mean diameters of 143.8, 173.9, and 203.4 nm, respectively. They had spherical, smooth surfaces, and zeta potential of +28.4 mV for thyme–garlic-loaded CS/ALG NCs. The bactericidal efficacy of loaded NCs with mixed oils outperformed individual loaded oils and ampicillin, against foodborne pathogens. Staphylococcus aureus was the most susceptible (with 28.7 mm inhibition zone and 12.5 µg·mL−1 bactericidal concentration), whereas Escherichia coli was the most resistant (17.5 µg·mL−1 bactericidal concentration). Scanning electron microscopy images of bacteria treated with NCs revealed strong disruptive effects on S. aureus and Aeromonas hydrophila cells; treated cells were totally exploded or lysed within 8 h. These environmentally friendly nanosystems might be a viable alternative to synthetic preservatives and be of interest in terms of health and food safety.

Evaluation of the Antioxidant and Antimicrobial Potential of SiO2 Modified with Cinnamon Essential Oil (Cinnamomum Verum) for Its Use as a Nanofiller in Active Packaging PLA Films

“…Jabir et al [65] fabricated gold nanoparticles modified with glutathione and linalool and reported a MIC for E. coli bacteria of 0.77 µg mL −1 and 1.54 µg mL −1 for S. aureus. Elghobashy et al [66] elaborated on chitosan nanocomposites with alginate loaded with thyme and essential garlic oil and showed that the bactericidal efficacy of essential oils improved when these were combined, the MIC obtained for E. coli was 15 µg mL −1 , while for S. aureus it was 7.5 µg mL −1 , and these values were lower than those obtained. We can say that essential oils are effective against the inhibition of Gram-positive and Gram-negative bacteria when transferred to other materials.…”

Chitosan/Alginate-Based Nanoparticles for Antibacterial Agents Delivery

“…Particularly for organic substituents like oils, a more suitable approach involves formulating them using the oil-in-water emulsification method, followed by combining them with ionic gelation. 106 , 124 , 127 , 130 , 133 This method not only enhances the encapsulation of oils but also improves the stability of the active ingredients, preventing their premature release during storage.…”

“… [ 129 ] Thyme essential oil (TEO) and garlic essential oil (GEO) Oil-in-water emulsification combined with ionic gelation method In vitro Staphylococcus aureus, Escherichia coli , and Aeromonas hydrophila MIC (in S. aureus ): TEO-loaded NPs = 10 µg/mL GEO-loaded NPs = 12.5 µg/mL TEO-GEO-loaded NPs = 7.5 µg/mL Chitosan components, besides serving as nanostructure formers, also provide a synergistic effect through interactions with essential minerals on bacteria and forming a film on the bacterial surface, preventing nutrient entry into bacterial cells. [ 130 ] Grape pomace extract Ionic gelation method In vitro Methicillin-susceptible Staphylococcus aureus (MSSA), Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis , and Listeria monocytogenes Encapsulation of grape pomace extract into NPs exhibit highest bacterial reduction against MMSA: 5-log reduction (higher than raw extract, 3-log reduction) The use of encapsulation systems into chitosan and alginate provides protection effects for antibiotic components in the extract (anthocyanins and neochlorogenic acid), thus enabling antibacterial effects even upon delivery to the intestines. [ 131 ] Artocarpus lacucha Roxb.…”

“…These range from single chemical constituents such as quercetin and curcumin to oils like oregano oil and various essential oils, as well as crude extracts. 106,[123][124][125][126][127][128][129][130][131][132][133][134] Ionic gelation, either alone or in combination with polyelectrolyte complexation techniques, is predominantly employed across the encapsulation of various types of natural-source materials. Particularly for organic substituents like oils, a more suitable approach involves formulating them using the oil-in-water emulsification method, followed by combining them with ionic gelation.…”

Essential-Oils-Loaded Biopolymeric Nanoparticles as Strategies for Microbial and Biofilm Control: A Current Status

“…In 2022, Elghobashy et al [ 149 ] conducted a study where they developed a chitosan/alginate nanocomposite loaded with thyme and garlic EOs. The researchers fabricated NPs using this composite and loaded them with the EOs, resulting in particles ranging from 150 to 200 nm in size and possessing a Z-potential of approximately 30 mV.…”