Antibacterial Properties of Oregano Essential Oil Encapsulated in Poly(ε-Caprolactone) Nanoparticles

This work describes an outstanding synthesis of poly(ε-caprolactone) nanoparticles of distinct sizes loaded (PCLNP/OEO) or not (PCLNP) with oregano (Origanum vulgare) essential oil (OEO) by the nanoprecipitation method in order investigate the antimicrobial properties against bacteria Escherichia coli and Staphylococcus aureus. OEO antimicrobial activity was achieved by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). FTIR spectra indicated that encapsulation of OEO by PCLNPs was successful. Scanning electron microscopy images revealed that PCLNP and PCLNP/OEO presented spherical shape with diameters around 150 nm, while PCLNP exhibited size distribution raging 158 to 300 nm and zeta potential ranging from -13.8 to -28.5 mV. Thermogravimetric analysis indicated an increase in initial temperature of weight loss for PCLNP/OEO. PCLNP with 80% wt. of OEO has exhibited the highest decrease of growth of bacteria, and MIC against S. aureus and E. coli and MBC only for E. coli, which indicate a promising alternative for designing stable antimicrobial nanoparticles for application in novel food active packaging.