Microfluidic-Based Formulation of Essential Oils-Loaded Chitosan Coated PLGA Particles Enhances Their Bioavailability and Nematocidal Activity

In this study, poly (lactic-co-glycolic) acid (PLGA) particles were synthesized and coated with chitosan. Three essential oil (EO) components (eugenol, linalool, and geraniol) were entrapped inside these PLGA particles by using the continuous flow-focusing microfluidic method and a partially water-miscible solvent mixture (dichloromethane: acetone mixture (1:10)). Encapsulation of EO components in PLGA particles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction, with encapsulation efficiencies 95.14%, 79.68%, and 71.34% and loading capacities 8.88%, 8.38%, and 5.65% in particles entrapped with eugenol, linalool, and geraniol, respectively. The EO components’ dissociation from the loaded particles exhibited an initial burst release in the first 8 h followed by a sustained release phase at significantly slower rates from the coated particles, extending beyond 5 days. The EO components encapsulated in chitosan coated particles up to 5 μg/mL were not cytotoxic to bovine gut cell line (FFKD-1-R) and had no adverse effect on cell growth and membrane integrity compared with free EO components or uncoated particles.

Chitosan coated PLGA particles loaded with combined EO components (10 µg/mL) significantly inhibited the motility of the larval stage of Haemonchus contortus and Trichostrongylus axei by 76.9%, and completely inhibited the motility of adult worms (p < 0.05). This nematocidal effect was accompanied by considerable cuticular damage in the treated worms, reflecting a synergistic effect of the combined EO components and an additive effect of chitosan. These results show that encapsulation of EO components, with a potent anthelmintic activity, in chitosan coated PLGA particles improve the bioavailability and efficacy of EO components against ovine gastrointestinal nematodes.

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Materials

The following chemicals were purchased from Sigma-Aldrich (St. Louis, MO, USA): Poly(D,L-lactide-co-glycolide) (PLGA; lactide:glycolide 65:35, MW 40–75 KDa), Poly(vinyl alcohol) (PVA; 87%–89% hydrolyzed, MW = 13–23 KDa), sucrose, sodium tripolyphosphate (TPP; MW = 367.86), medium molecular weight chitosan (MW = 50–190 KDa), polysorbate 80, span 20, fluorescein 5(6)-isothiocyanate (FITC), clove oil (Eugenia caryophyllata), lavender oil (Lavandula angustifolia), pure components (~100% purity), and analytical standards of linalool and geraniol. Pure eugenol was obtained from flourochem Ltd. (Glossop, UK). The essential oils citronella (Cymbopogon nardus) and coriander (Coriandrum sativum) were purchased from Oils4life Ltd. (Great Yarmouth, UK). Dichloromethane (DCM) and acetone were obtained from Fisher Scientific Inc. The analytical standards of eugenol were purchased from the European Pharmacopoeia (EP) reference standards.

Helal, M.A.; Abdel-Gawad, A.M.; Kandil, O.M.; Khalifa, M.M.E.; Morrison, A.A.; Bartley, D.J.; Cave, G.W.V.; Elsheikha, H.M. Microfluidic-Based Formulation of Essential Oils-Loaded Chitosan Coated PLGA Particles Enhances Their Bioavailability and Nematocidal Activity. Pharmaceutics 2022, 14, 2030. https://doi.org/10.3390/pharmaceutics14102030