Desenvolvimento de nanocápsulas contendo óleo essencial de Melaleuca alternifolia e Azitromicina

Abstract

The problem of resistance to classical antimicrobials has led to the study and development of new drug systems that combine classical antimicrobials with natural compounds. This study aimed to produce nanocapsules of Tea Tree Oil (TTO) and Azithromycin (AZI) coated with Chitosan (CH) with antimicrobial activity. The nanocapsules suspensions were prepared using the pre-formed polymer interfacial precipitation method. They were coated with a 2% CH solution. The physicochemical characterization included evaluation of pH, mean hydrodynamic diameter (z-average), Zeta Potential (Zp), polydispersity index (Pdi), essential oil encapsulation efficiency (EE), and morphological assessment using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The biological tests performed were Minimum Inhibitory Concentration (MIC) tests, Minimum Bactericidal Concentration (MBC) tests, and cell viability tests. The z-average found for the nanocapsules suspensions before CH coating was smaller than the z-average after the process, suggesting the formation of a thin CH layer around the nanocapsules. The Pdi values showed that the suspensions maintained their homogeneity regarding particle size and distribution even after coating. The Zp, which was initially negative, became positive after coating. Furthermore, an increase in Zp was observed in TTO nanocapsules after coating. The pH became more acidic due to the presence of CH in the suspension. The average encapsulation efficiency of TTO was 89.89±1.29%. In the SEM images, after coating with CH, the spherical/oval shape of the nanocapsules was visible. AFM images confirmed the nanoscale size of the nanocapsules and their distribution in the system. The MIC values for encapsulated TTO and AZI were lower than those of the two bioactives in their free form for all bacteria within a 24-hour period. NP-TTO-AZI-CH showed bactericidal activity, and viability was maintained at 70% in the first 24 hours at concentrations of 0.5mg/mL+20μg/mL to 0.0625mg/mL+2.5μg/mL. NP-TTO-AZI-CH proved to be a promising approach in combating all bacterial strains tested.