Morphological and structural evaluation of nanoparticles loaded with tea tree oil for the therapeutic treatment of HPV

The human papillomavirus (HPV) is a sexually transmitted disease with a high number of cases. To seek a less intrusive treatment, there is a search for new drugs that act on the epithelial base, preventing tissue hyperproliferation. In this context, Tea tree oil (TTO) stands out due to its antioxidant, antifungal, antibacterial, anti-inflammatory, and anti-hyperproliferative potential. However, TTO presents little to no solubility in water which strongly limits its application in mucosal regions that are normally affected by HPV lesions. In this sense, the nanoencapsulation is a viable maneuver capable of protecting the active and increase its solubility in water, promoting greater compatibility and bioavailability. The main objective of this study was to evaluate the morphology and structure of PCL/F-127 polymeric nanoparticles loaded with 10–30% w/w of TTO (NNP 0%, NNP 10% TTO, NNP 20% TTO and NNP 30% TTO) obtained by nanoprecipitation. The particles loaded with TTO obtained a hydrodynamic size between 180 and 220 nm with stability in colloidal suspension for three months. The spherical shape and nanometric dimensions were verified by TEM. Besides that, TTO showed a strong antioxidant action and exhibited cryoprotective action reducing particle increase in the lyophilization process. Also, the absence of chemical interactions between the TTO and the polymeric matrices that make up the NNPs was observed, and it was established that the obtained systems were not cytotoxic when in contact with the L929 fibroblast lineage. The matrices, in turn, showed adequate ability to protect the active against degradation and volatilization by thermal action as indicated by TGA and DDPH techniques. Also, the addition of the oil favored higher stability of the systems and generated an increase in their crystallinity. The results indicate that the TTO is promising not only as an active to be encapsulated but also as a component for stabilizing PCL/Pluronic nanoprecipitation systems to obtain nanoparticles.