Encapsulation of eucalyptus essential oil in chitosan nanoparticles and its effect on MDA-MB-231 cells

Encapsulation of essential oil in polymeric nanoparticles (NPs) increases their retention and improves their efficacy. Here, eucalyptus essential oil (EEO) encapsulate in the chitosan (CS) NPs increases its retention, and enhances the anticancer effect of EEO.

The effects of pH, chitosan sodium tripolyphosphate ratio, and chitosan concentration on the size and charge NPs were evaluated. The success of EEO encapsulation was confirmed by FT-IR, UV–Vis spectroscopy, and GC techniques. The toxic effect of free EEO and CS-EEO NPs was investigated in MDA-MB-231 breast cancer cells and fibroblast normal cells. 

The optimized obtained EEO -loaded chitosan nanoparticles (CS-EEO NPs) were spherical with an average diameter of 86 nm, a polydispersity index below 0.4, and positive zeta potential (+14.25 mV) as confirmed. Increasing the concentration and pH of the chitosan solution and decreasing the chitosan/sodium tripolyphosphate ratio, the size of NPs decreased. Loading capacity (LC) and encapsulation efficiency (EE) of EEO in the NPs were about 45% and 32–76%, respectively. The chitosan nanoparticles exhibited a biphasic release profile with the release of 87% of the EEO in the first 5 h, followed by a sustained release for the next 43 h. 

The free EEO was more toxic for MDA-MB-231 cells than fibroblast cells; however, CS-EEO NPs were non-toxic for fibroblast cells and more toxic for MDA-MB-231 cells compared to free EEO. Therefore, the CS-EEO NPs illustrate smart behavior in killing cancerous cells and will be suggested for breast cancer drug delivery.