Superoxide dismutase-contained solid lipid nanoparticles: Formulation development and In-vivo evaluation for second-degree burn wound healing in rats

Superoxide dismutase (SOD), a natural enzyme with high antioxidant activity, reduces injury and accelerates wound healing by scavenging superoxide radicals. This enzyme plays an important role in cellular defense against oxidative stress such as burn injury. The aim of this study was to load SOD into solid lipid nanoparticles for the treatment of rat burn wounds. Solid lipid nanoparticles were prepared by Solvent Emulsification Diffusion method and evaluated for particle size, enzyme activity and enzyme entrapment efficiency. Twenty-seven rats in 3 different groups were induced with deep second-degree burns and then treated with SOD-loaded solid lipid nanoparticles, solid lipid nanoparticles without enzyme, or SOD solution. After the treatment period, the wounds were evaluated macroscopically for the area of healing and microscopically for indices of re-epithelialization, granulation tissue and angiogenesis. The optimized SOD-loaded solid lipid nanoparticles showed a particle size of 35–85 ± 2.41 nm, 78.4 ± 4.31 % entrapment efficiency and 90 % initial enzyme activity. Macroscopic examination showed that the best recovery rate belonged to the solid lipid nanoparticle group. Pathological studies also showed that angiogenesis and granulation tissue were significantly better in this group. Compared to the other two groups, SOD-loaded solid lipid nanoparticles showed a significant improvement in pathological factors, particularly angiogenesis and granulation tissue, as well as a faster reduction in the number of inflammatory cells. Based on this study, solid lipid nanoparticles could be used as an effective delivery system for SOD in the treatment of second-degree burns. •One of the new strategies in the development of the pharmaceutical industry is the use of nanotechnology.•The use of solid lipid nanoparticles as a novel drug delivery system to deliver superoxide dismutase to second-degree burns.•The system can help the enzyme penetrate into the deep layers of the skin, therefore more effective in the treatment of burns.•The system can protect the enzyme against environmental deteriorations.•The enzyme released from such carrier is slow and sustained so that there is no need to repeated doses.