| Summary: | 碩士 === 臺北醫學大學 === 生物醫學材料研究所 === 93 === Rhizopus stolonifer was a common fungus in nature and it was frequently used for food fermentation. The purpose of the present study was to use the cell wall of R. stolonifer as a new source of chitin for a potential biomedical material in wound dressing. Chitin was the second most abundant biopolymer on Earth and found mainly in crustaceans shells and insects as well as cell wall of fungi mycelia. The considerably safe and fast-growing properties of R. stolonifer was the key design in the present study by culturing the mycelia to form an interwoven mattress named RHIZOCHITIN. The analyses for sugar composition of RHIZOCHITIN was carried out by hydrolyzed 5 mg of RHIZOCHITIN in sealed ampules with 3 ml trifluoroacetic acid at 110℃ for 16 hr and then the dried hydrolysate was analyzed by thin layer chromatography（TLC）. The results indicated that RHIZOCHITIN contained N-acetyl-D-glucosamine, the monomer of chitin, visualized by Elson-Morgan reagent. The glucosamine of RHIZOCHITIN analyzed by Elson-Morgan method was contained 27％, and compares with commercial chitin hydrolisis rate was contained 78.49 %. The glucosamine of RHIZOCHITIN analyzed by Elson-Morgan method was contained 78％. To avoid the formation of dark-colored sporangium produced in the late stage of culture, medium with various C/N ratio was tested. The desirable condition to obtain the maximal yield with the minimal sporangium was using PDB（potatoes dextrose broth）with additional 2% glucose at 29℃ for 8 days. Mutagenesis was also carried out to select strain of few sporangia formation. Sixteen mutant strains were selected with less sporangia formation and mutant strain No.6 was the lead candidate for the following study. Instead of flask culture, tray system was used for a scale-production of RHIZOCHITIN. Inoculation density of sporangial spore were found independent to the mass and thickness of RHIZOCHITIN ; in a range from 1☓107 spores /ml to 1☓108 spores /ml. However, the volume of medium was positively correlated with the thickness and total mass of RHIZOCHITIN. In average, the thickness of RHIZOCHITIN decreased in the tray system, but the total production was not significantly changed when the volume of medium was considered. Animal model with Wistar rats was employed for wound healing test. Full thickness excision wounds of 6 mm in diameter were created and identical size of RHIZOCHITIZ was applied to the wound with BESCHITIN-W and SACCHACHITIN as positive controls. The effect on the acceleration of wound was significant when compared to control groups. Growth factors including TGF-β and VEGF content were 3.62 folds on the 3rd day and VEGF was 1.68 fold on the 9th day of the untreated group. Matrix metalloproteinases analysis also indicated an attenuation effect of RHIZOCHITIN in the wound to a lower level that could enhance collagen and growth factor piling. All the results demonstrated that RHIZOCHIRIN could be a promising material for biomedical purposes.
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