Chitosan microparticle-based antibacterial nasal barrier formulation and in vivo evaluations.

Microorganisms remain a major cause of infectious diseases, emphasizing the need for alternative and complementary antimicrobial strategies. In this context, plant-derived materials have attracted increasing attention for their antimicrobial and protective properties. Chitosan, a biocompatible and cationic biopolymer, has emerged as an effective carrier system for encapsulating such plant-derived components. In this study, chitosan microparticles were prepared through ionic gelation followed by spray drying and loaded with thyme oil and olive leaf extract. The resulting microparticles exhibited an average size of approximately 1.8 μm and a total phenolic content of 23 mg GAE/g. These microparticles were incorporated into a glycerin-starch ointment to develop a nasal barrier formulation. The formulation showed physicochemical properties compatible with intranasal administration, with pH values in the range of 5-7. The antibacterial activity of the formulation was tested in vivo using BALB/c mice, in which a time-dependent reduction in microbial viability was observed after intranasal administration. Overall, these results suggest that chitosan-based microparticle systems containing plant-derived components could serve as nasal barrier formulations with supportive antibacterial effects.