A Primary Study On Agar-based Composites For Skin Wound Dressing

Biomaterials from the ocean are attracting more eyes nowadays, particularly, they may bring huge economic, environmental and social benefits besides biomedical applications. Extracted from Gracilaria lemaneiformis, Gelidium amansii, Porphyra haitanensis or other algaes, agar is one of the polysaccharides which has a special gel property and favorable biocompatibility. It has been widely used in cell culture and electrophoresis analyses. In our study, the physical characteristics and chemical structure of the agar used has been analysed firstly. A novel biomaterial based on agar was studied and used as skin wound dressing.Agar, a highly hydrophilic polymer, has a low intension strength in an aqueous condition, so a cross-linking process is needed for its applications as skin wound dressing. In this paper, glutaraldehyde(glut.) was chosen as a cross-linking agent, and an acidic condition was crucial to achieve a quick cross-link reaction. The most favorable condition for cross-linking was that the weight ratio of agar to glut, being 66.7 and the pH value about 5. In order to tailor multiple properties of both mechanical intension and degradable ability, poly (vinyl alcohol) or type I collagen was mixed with agar in a certain ratio, and cross-linked. For a composite membrane by drying it at 50℃, while for a scaffold by a freeze-dry process. Results of analyses by FT-IR, DMA and optical microscope showed that the composite membrane had a moderate modulus, had a low uptake of water after cross-linked, and the pores were interconnected in the composite scaffolds instead of honeycomb-like pores in pure agar sample. Results of acute toxicity test disclosed that the composites had no toxic to rats although the composites were cross-linked by a fitting concentration of glutaraldehyde. In vivo experiments, results showed that when the composite membranes or scaffolds were applied to repair rabbit skin lesion, the composites had good repair effects without infection, liquid exudation or visible scar in the lesion covered with them. But in control group, the autologous skin could not cure the lesion that fast and well. H&E staining results showed that the repair tissue was normal and few scaffolds or membranes were left not degradable after 2 or 3 weeks. In conclusion, it is proved that the agar-based composites are promising biomaterials as wound dressing for burn and ulcer curing.