Evaluation of the safety and healing potential of a fibroin-aloe gel film for the treatment of diabetic foot ulcers

Objective: This study aimed to develop a wound dressing prepared from the blending of silkworm fibroin and aloe gel extract for use in the treatment of diabetic foot ulcers (DFUs). Methods: Fibroin extracted from silkworm cocoons and aloe gel extract were dissolved in deionised water. pH levels were then adjusted with lactic acid solution. A simple casting technique was used to obtain the fibroin-aloe gel film. The surface morphology, hardness, flexibility and infrared spectrum of the sterilised film were tested. Swelling ratio was measured from changes in weight. The cytocompatibility of the film to human dermal fibroblast was determined using XTT assay. Hard-to-heal DFUs (grade I Wagner score) were treated with the film for four weeks. The application site was assessed for allergic reactions and/or sensitisation. Wound size was measured using standardised digital photography. Results: A total of five hard-to-heal DFUs were treated. The obtained film sterilised with ozonation showed a non-porous structure. The elongation at break and tensile strength of the wet film were 9.00 +/- 0.95% and 6.89 +/- 1.21N, respectively. Fourier-transform infrared spectroscopy data indicated the presence of amides I, II and III, of peptide linkage, which are the chemical characteristics of the fibroin. Functional groups relating to healing activity of the aloe gel extract were also found. The swelling ratio of the film immersed in water for 24 hours was 0.8 +/- 0.01. In three DFUs (40-50mm(2) in size), a wound area reduction of 0.4-0.8mm(2)/day was observed and were healed in 2-3 weeks. The remaining two SFUs (500mm(2) in size) showed a wound area reduction of 4mm(2)/day and were almost closed at four weeks. No allergic reaction or infection was observed in any of the wounds. Conclusion: The obtained film showed a non-porous structure, and its strength and flexibility were adequate for storage and handling. The film tended to increase the proliferation of fibroblasts. The wound dressing showed potential for accelerating the healing rate of DFUs.