Avaliação de eficácia antimicrobiana de óleo essencial de hortelã pimenta incorporado em nanopartículas de sílica mesoporosa tipo mcm 41

Abstract

This study addresses a recurring limitation in the application of bioactive essential oils, related to their high volatility and thermal instability, and proposes an efficient, environmentally friendly encapsulation strategy with potential application in antimicrobial systems. The investigation focused on the incorporation of peppermint essential oil (OEHP) into mesoporous silica nanoparticles of the MCM-41 type, both non-functionalized and amino-functionalized, with the aim of evaluating thermal stability, release kinetics, and antimicrobial activity of the system. OEHP was selected due to its widely recognized bioactive properties and intrinsic application limitations, such as high volatility and low stability under environmental factors, which motivate the development of encapsulation strategies. Two incorporation routes were applied, with emphasis on forced incorporation by rotary evaporation, adapted for the use of environmentally suitable solvents, in addition to adsorption assays. The obtained nanoparticles exhibited an average size of 153 ± 36 nm and a pore diameter of 2.72 ± 0.36 nm, with incorporation efficiency of up to 94.4 %. Thermogravimetric assays demonstrated that amino functionalization increased OEHP retention and provided greater thermal stability, especially at moderate temperatures such as 60 °C and 80 °C. Release assays in solvent, monitored by UV-Vis spectrophotometry, allowed qualitative evaluation of OEHP behavior during the release process, revealing distinct profiles between the studied materials. Non-functionalized MCM-41 exhibited faster release with characteristics of a burst release of a large amount of active compound, whereas amino-functionalized MCM-41 displayed a more gradual and controlled profile, associated with stronger interactions between the silica surface and the essential oil compounds. Kinetic analysis indicated that the release behavior best fitted the Korsmeyer model, suggesting release control by the porous structure and by interactions between the matrix surface and active compounds. In vitro assays demonstrated inhibition halos for the functionalized nanoparticles against S. aureus. The results indicate that amino-functionalized MCM-41 constitutes a promising platform for OEHP incorporation, with advantages in stability, release efficiency, and antimicrobial activity, contributing to the advancement of controlled release systems based on mesoporous silica through more sustainable and efficient routes.