Evaluation of physical properties and antibacterial activity of bioactive compounds-loaded chitosan nanoparticles

Bioactive compounds such as essential oils (EO), botanical extracts and natural resins are well known to have beneficial properties. Among these properties are their antibacterial activity. A disadvantage of these compounds is that they are volatile. Therefore, encapsulation is a good way to overcome this problem. In this study, the morphology, particle size distribution, Zeta potential and microbiological activity of chitosan nanoparticles incorporated with three different bioactive compounds having antimicrobial properties: ethanol extract of propolis, thyme essential oil and ethanol extract of Byrsonima crassifolia (L.) Kunth were evaluated. Nanoparticles were synthesized using the nanoprecipitation method. The morphology was observed using transmission electron microscopy (TEM). Also, particle size distribution and Zeta potential were measured. Results show spherical in shape nanoparticles. Thyme essential oil-loaded chitosan nanoparticles (TEO-CSNPs) showed the smallest particle size and highest stability as assessed by Zeta potential measurement, followed in stability by ethanol extract of propolis-loaded chitosan nanoparticles (EEP-CSNPs), ethanol extract of Byrsonima crassifolia (L.) Kunth (EEBC-CSNPs) and finally by chitosan nanoparticles (CSNPs). The antibacterial activity of the bioactive compounds-loaded chitosan nanoparticles was evaluated against Staphylococcus aureus. The highest antibacterial activity was observed for TEO-CSNPs with an inhibition halo (IH) value of 10.54±0.78 mm, followed by EEP-CSNPs (8.10±1.19 mm). EEBC-CSNPs and CSNPs did not show zone of inhibition. Bioactive compounds-loaded chitosan nanoparticles represents a good alternative for bacterial control of food borne pathogens in applications for fruits and vegetables conservation.