Antioxidant and antimicrobial poly-ε-caprolactone nanoparticles loaded with Cymbopogon martinii essential oil

Palmarosa (Cymbopogon martinii) essential oil is a rich source of geraniol monoterpene, with antimicrobial and antioxidant properties. However, bioactive compounds present chemical instability under adverse temperature conditions due to their high volatility characteristics. Therefore, the aim of this work was to produce poly-ε-caprolactone nanoparticles entrapped with palmarosa essential oil and geraniol, the majoritarian compound of palmarosa essential oil. Entrapped nanoparticles were characterized by particle size, polydispersity index, zeta potential, morphology, encapsulation efficiency, differential scanning calorimetry (DSC), antioxidant capacity and antimicrobial activity. The average sizes of the loaded nanoparticles was 282.1 ± 0.4 nm and 289.3 ± 1.5 nm, for geraniol and palmarosa oil respectively, and 207.8 ± 0.1 nm for the free loaded nanoparticles. The polydispersity results were lower than 0.140, indicating a unimodal distribution. All formulations showed zeta potential lower than 30 mV, indicating a good stability. High values of encapsulation efficiency were obtained, explained by the hydrophobicity of the essential oil and geraniol. Evaluating the morphology, nanoparticles presented a spherical shape, with a capsular structure. The encapsulation was confirmed by DSC, by changes in onset and endset temperatures, when the nanoparticles were compared to the pure compounds. Nanoparticles presented antioxidant activity against DPPH free radical and positive inhibition results against Staphylococcus aureus and Escherichia coli. Based on the results obtained, poly-ε-caprolactone nanocapsules presented good physicochemical characteristics, suggesting applicability in perfumery, cosmetics, and in the pharmaceutical industries. [Display omitted] •Poly-ε-caprolactone (PCL) nanoparticles were obtained by nanoprecipitation technique.•High values for encapsulation efficiency of the hydrophobic compounds were obtained.•The formulations showed good stability with a zeta potential lower than 30 mV.•Nanoparticles with palmarosa essential oil and geraniol present a high antioxidant activity.•Loaded nanoparticles present antibacterial activity against S. aureus and E. coli bacteria.