Purpose: Diabetic foot ulcer (DFU) is one of the most serious complications in diabetic patients. DFU is identified as a chronic wound because inflammation phase of wound healing process is prolonged with an elevated level of proteases and, often accompanied by bacterial infections. We hypothesized that a drug delivery system encapsulating epidermal growth factor (EGF) and lysozyme such as niosomes would circumvent proteolytic degradation of these proteins in chronic wound bed and therefore, enhance their wound healing and anti-microbial activity.
Methods: Thin-film hydration and one-step sonication methods were compared to prepare BSA and lysozyme loaded niosomes. Considering the size of niosomes and several advantages of one-step sonication method over thin-film hydration method, the former was chosen for further studies. Niosomes were characterized with respect to their size, polydispersity index, physical stability, protein encapsulation efficiency, protein stability, and in vitro antibacterial activity of lysozyme loaded niosomes.
Results: With the one-step sonication method, the entrapment efficiency for EGF and lysozyme were 64.4% and 90.9% respectively. The release rates of EGF and lysozyme from niosomes depended on the osmotic pressure of niosome hydration media, which could be attributed to the swelling of niosomes hydrated in 30% sucrose solution in PBS as shown by TEM. Lysozyme loaded niosomes reduced the bacterial growth rate more effectively than lysozyme solution and such activity depended on the osmotic pressure of noisome hydration media. Characterization of EGF loaded niosomes is under progress.
Conclusion: In conclusion, one-step sonication method demonstrated feasibility to prepare niosomes with good encapsulation efficiency for protein drugs. The release rates of EGF and lysozyme from niosomes can be modulated by the osmotic pressure of niosome hydration media. Better antibacterial activity of lysozyme loaded niosomes compared to lysozyme solution suggests that EGF/Lysozyme loaded niosomes by one-step sonication method have the potential to be developed as a novel DFU treatment.