Enhancing the Antioxidant, Antibacterial, and Wound Healing Effects of Melaleuca alternifolia Oil by Microencapsulating It in Chitosan-Sodium Alginate Microspheres

Abstract

In this study, antibacterial and antioxidant molecules-rich Melaleuca alternifolia oil (tea tree oil (TTO)) loaded chitosan (CS) based nanoemulsions (NEMs) were prepared and encapsulated by sodium alginate (SA) microsphere for antibacterial wound dressing. CS-TTO NEMs were prepared by oil-in-water emulsion technique, and the nanoparticle tracking analysis (NTA) confirmed that the CS-TTO NEMs had an average particle size of 89.5 nm. Further, the SA-CS-TTO microsphere was confirmed through SEM analysis with an average particle size of 0.76 ± 0.10 µm. The existence of TTO in CS NEMs and SA encapsulation was evidenced through FTIR analysis. The XRD spectrum proved the load of TTO and SA encapsulation with CS significantly decreased the crystalline properties of the CS-TTO and SA-CS-TTO microsphere. The stability of TTO was increased by the copolymer complex, as confirmed through thermal gravimetric analysis (TGA). Furthermore, TTO was released from the CS–SA complex in a sustained manner and significantly inhibited the bacterial pathogens observed under confocal laser scanning microscopy (CLSM). In addition, CS-TTO (100 µg/mL) showed antioxidant potential (>80%), thereby increasing the DPPH and ABTS free radicals scavenging ability of SA-CS-TTO microspheres. Moreover, CS and SA-CS-TTO microsphere exhibited negligible cytotoxicity and augmented the NIH3T3 cell proliferation confirmed in the in vitro scratch assay. This study concluded that the SA-CS-TTO microsphere could be an antibacterial and antioxidant wound dressing.

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.…”

“… [ 126 ] Melaleuca alternifolia (tea tree) Oil (TTO) Oil-in-water emulsification combined with thin film dispersion method In vitro Bacillus cereus, Staphylococcus aureus, Escherichia coli , and Salmonella enterica MIC (in B. cereus ): Alginate NPs = 250 µg/mL Chitosan NPs = 250 µg/mL Free TTO = 62.5 µg/mL TTO-loaded NPs = 62.5 µg/mL Nanoparticle systems do not enhance the antibacterial effect of tea tree oil but maintain antibacterial efficacy during delivery through extended-release mechanisms. [ 127 ] Curcumin Polyelectrolyte complexation technique In vitro Streptococcus mutans Curcumin-loaded NPs exhibit higher bacterial reduction than free curcumin Apart from the gradual release mechanism of curcumin, strong ionic interactions between nanoparticles and bacterial cell walls help increase drug contact time with bacteria. [ 128 ] Solanum nigrum L. leaf extract Ionic gelation technique In vitro Streptococcus aureus, Pseudomonas aeruginosa, Escherichia coli , and Bacillus subtilis MIC (in P. aeruginosa ): NPs = <230 µg/mL Raw extract = 1560 µg/mL Extract-loaded NPs = <230/195 µg/mL Nanoparticle systems enhance antibacterial effects due to the synergistic effect between chitosan and the extract.…”

“…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.…”

Stabilization of Essential Oil: Polysaccharide-Based Drug Delivery System with Plant-like Structure Based on Biomimetic Concept

“…Hence, the EO droplets are respectively protected by either a dense polyelectrolyte layer or by aggregation formed via attraction between opposite charges. Anbazhagan et al [ 100 ] prepared a tea tree EO–chitosan nanoemulsion, and slowly added it to sodium alginate solution, follow by dropping, stirring, and ultrasonic dispersion; then, tea tree EO-chitosan–sodium alginate microspheres were formed. Its LE% is up to 15% and its EE% is 71%.…”