Peppermint essential oil and ZnO nanoparticles: A green and effective combination for a cooling bilayer patch with antibacterial activity

Nowadays, comprehensive research has been done all over the world regarding the biomedical, pharmaceutical, and environmental applications of hydrogels. Hydrogel patches are widely used for wound healing due to their biocompatibility, biodegradability, and hydration capability. In this study, a bilayer hydrogel patch was developed, which consists of a back layer of polyvinyl alcohol (PVA) and a front layer of sodium alginate (SA) containing peppermint essential oil (PEO) and zinc oxide nanoparticles (ZnO NPs). A thermal camera showed the cooling effect of PEO on the hydrogel patch. PEO contains a high concentration of menthol, which is a compound that activates transient receptor potential melastatin 8 (TRPM8) channels in the skin, which leads to a feeling of skin coolness. The results showed that the antibacterial, antioxidant, and hemostatic properties of hydrogel patches were increased by PEO and ZnO NPs. The wound healing performance of hydrogel patches on rats was also evaluated for 14 days. Wound closure was accelerated by the hydrogel patch containing PEO and ZnO NPs, inflammation was reduced, collagen synthesis was increased, and skin structure and function were restored. Therefore, it was concluded that the hydrogel patch containing PEO and ZnO NPs is a promising candidate for wound healing applications.