Fabrication of lavender essential oil-loaded polyurethane nanoparticles via a facile swelling-diffusion method as hydrocolloid agents for wound healing applications

Colloidal agents or polymeric nanoparticles, in which the drug can be encapsulated and released in a controlled way, are currently interesting approaches for wound healing owing to their intrinsic properties. This work proposes a facile and efficient strategy for developing polyurethane (PU) nanoparticles as modern hydrocolloid dressing agents for wound healing applications. Preformed PU nanoparticles (hydrocolloid) were utilized as a template for simple swelling-diffusion of lavender essential oil (LO). The LO phase dissolved in ethanol/water mixture at different volume ratios was gently mixed with PU hydrocolloid. Due to the high miscibility between LO and the PU matrix, LO diffused and entrapped into the PU nanoparticles. The effect of ethanol/water ratios on the colloidal stability, encapsulation efficiency (%EE), and loading capacity (%LC) of the obtained LO-loaded PU (LO@PU) nanoparticles was studied. With ethanol/water at 0/100, the stable LO@PU nanoparticles with high EE and LC of 59.67% and 27.98%, were obtained. The release behavior of LO from the LO@PU nanoparticles in phosphate buffer at pH 8.5 (suitable for practical use in wound healing applications) showed sustained release for 192 h. The cytotoxicity assay performed using the fibroblast cells showed a high cell viability of similar to 80% at the highest concentration of nanoparticles (1 mg/mL), reflecting their biocompatibility. The encapsulated PU nanoparticles can be made into a transparent soft film, which showed antibacterial activity against both Staphylococcus aureus and Escherichia coli. These results suggest that the prepared LO@PU hydrocolloid has a high potential for wound healing applications.