| DOI: 10.29090/psa.2026.03.26.9363 | Pharm Sci Asia 2026; 53(3), 368-381 |
Ternary-structured chitosan-stabilized nanoemulsions of Plectranthus amboinicus essential oil for enhanced antimicrobial performance in biomaterial applicationsKhanh Ngoc Le1, Dang Le Hai Hoang 2, Quang The Nguyen2, Thanh Tien Nguyen2, Anh Nam La2, Dung Phuoc Tran Nguyen3, Ngan Bao Hoang2, Quynh Nhu Thi Nguyen1, Nhung Mai-Hong Nguyen4, Bao Ngoc Tran4*
1 Hanoi University of Pharmacy, Faculty of Biotechnology, Hanoi, Vietnam
2 Hanoi – Amsterdam High School for the Gifted, Hanoi, Vietnam
3 Vietnam National University Hanoi, Hanoi, High School for Gifted Students, Hanoi, Vietnam
4 Hanoi University of Pharmacy, Faculty of Pharmaceutics-Pharmaceutical Technology, Hanoi, Vietnam
Plectranthus amboinicus essential oil (PAEO) is known for its antimicrobial activity; however, its hydrophobfic nature limits its dispersion and consistency in aqueous environments. This study proposed PAEO-loaded nanoemulsions using a ternary phase system composed of Tween 80, phosphate buffer (pH 7.4), and chitosan to overcome this limitation. The ternary diagram exhibited a homogeneous region corresponding to nanoscale formulations and indicated that Tween and chitosan contribute to the stabilization of the emulsion system. The addition of caprylocaproyl polyoxyl-8 glycerides (Labrasol) to phosphate buffer (pH 7.4) expanded the homogeneous area, indicating improved formulation flexibility. Compared with pure PAEO, all nanoemulsion formulations significantly reduced MIC and MBC values (p < 0.01). Chitosan-containing formulations (F1-4 and F2-4) exhibited the highest antimicrobial activity, achieving >99.9% microbial reduction within 30 s against Staphylococcus aureus, Escherichia coli, and Candida albicans. The results indicate that chitosan was the primary factor responsible for the enhanced antimicrobial performance, whereas Labrasol mainly improved physicochemical stability. The combination of PAEO, chitosan, and Labrasol therefore provides a ternary nanoemulsion system with both improved stability and rapid antimicrobial activity, highlighting its potential for biomedical applications. These results support the potential of PAEO nanoemulsions as fast-acting antimicrobial systems suitable for biomedical or topical applications.
Keyword:
Essential oil; Nanoemulsion; Chitosan; Antibacterial; Antifungal; Physical stability.
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