키틴, 키토산 나노섬유의 제조및 특성 분석 = Fabricaiton and characterization of chitin and chitosan nanofibers by electrospinning

다국어 초록 (Multilingual Abstract)

In recent years, both chitin and chitosan have received some attention as one of candidate materials for biomedical applications because it has several distinctive biological properties including good biocompatibility, biodegradability, and wound healing effect. Electrospinning has been recognized as an efficient technique for the fabrication of polymer nanofibers. These nanofibers are of considerable interest for various kinds of applications, because they have several useful properties such as high specific surface area and high porosity. Examples are fiber membranes for filter applications, biomedical applications, such as wound dressings and scaffolds for tissue engineering, and sensing applications.
The ultimate aim of this study is to develope a novel biodegradable wound dressings or scaffolds for tissue engineering composed of the eletrospun chitin (or chitosan) nanofibers. In the present study, chitin nanofibrous matrix was fabricated via electrospinning and its degradation behavior and cell behavior were investigated and compared with chitin microfibers, Chitin was depolymerized by gamma irradiation to improve its solubility. The electrospinning of chitin was performed with 1,1,1,2,2,2-hexafluoro-2-propanol (HFIP) as a spinning solvent. For deacetylation, as-spun chitin nanofibrous matrix was chemically treated with a 40 % aqueous NaOH solution at 60℃ or 100℃. With the deacetylation for 150 min at 100 or for 1day at 60℃, chitin matrix was transformed into chitosan matrix with DD=~85% without dimensional change (shrinkage). Morphology of as-spun and deacetylated chitin (chitosan) nanofibrs was investigated by scanning electron microscopy (SEM). This structural transformation from chitin to chitosan was confirmed by FT-IR and WAXD.
In vitro degradation, as-spun chitin nanofibers (Chi-N) and commercial chitin microfibers (Chi-M) were incubated in closed bottles containing lysozyme in a phosphate-buffered saline (PBS; pH 7.2) at 37℃. Morphology of Chi-N and Chi-M were investigated by SEM. From the image analysis, the average diameters of Chi-N and Chi-M were 163 nm and 8.77㎛, respectively. During in vitro degradation for 14days, the degradation rate of Chi-N was faster than that of Chi-M, Specially, Chi-N that were grafted into rat subcutaneous tissue were almost degraded within 28 days and no inflammation could be seen on the nanofiber surfaces or in the surrounding tissues. To assay and compare the cytocompatibility and cell behavior onto Chi-N and Chi-M, cell attachment of normal human keratinocytes and fibroblasts seeded on the Chi-N and Chi-M matrices and interaction between cells and chitin fibers were studied. Relatively high cell adhesion was observed on uncoated Chi-N compared with uncoated Chi-M, and Chi-N treated with type Ⅰ collagen or laminin were functionally active in responses in normal human keratinocytes and fibroblasts. Our results indicate that the Chi-N itself or Chi-N coated with ECM proteins, particularly type Ⅰ collagen, may be a good candidate for the biomedical applications, such as wound dressing and scaffolds for tissue engineering.

목차 (Table of Contents)

• 목차 = ⅰ
• List of Figures = ⅲ
• List of Tables = ⅶ
• Ⅰ. 서론 = 1
• Ⅱ. 이론적 배경 = 8
• 2.1 전기방사 = 8
• 2.2. 키틴, 키토산 = 15
• 2.3 생체 조직공학에서 나노섬유의 응용 = 23
• Ⅲ. 재료 및 실험방법 = 28
• 3.1. 키토산의 전기방사 = 28
• 3.1.1. 재료 = 28
• 3.1.2. 전기방사 = 28
• 3.2. 키틴의 전기방사 = 29
• 3.2.1. 재료 = 29
• 3.2.2. 재생키틴의 전기방사 = 29
• 3.2.3. 키틴의 전기방사 및 방사선 처리 = 29
• 3.3. 키틴 나노섬유의 탈아세틸화 및 탈아세틸화도의 측정 = 30
• 3.3.1 키틴 나노섬유의 탈아세틸화 = 30
• 3.3.2 탈아세틸화도의 측정 및 특성 분석 = 30
• 3.4. 생분해 실험 = 31
• 3.5. 세포 점착 및 배양 실험 = 31
• 3.6 특성분석 = 32
• Ⅳ. 결과 및 고찰 = 33
• 4.1. 키토산의 전기방사 = 33
• 4.1.1. 정제한 키토산의 전기방사 = 33
• 4.1.2. 글리콜 키토산의 전기방사 = 38
• 4.1.3. 고농도 산 수용액에서 키토산의 전기방사 = 38
• 4.2. 키틴의 전기방사 = 45
• 4.2.1. 재생 키틴의 전기방사 = 45
• 4.2.2. 키틴의 전기방사 = 46
• 4.2.3. 키틴의 방사선 처리 = 47
• 4.2.4. 방사선 처리된 키틴의 전기방사 = 51
• 4.3. 키틴 나노섬유의 탈아세틸화 및 특성분석 = 55
• 4.3.1 키틴 나노섬유의 탈아세틸화 = 55
• 4.3.2 탈아세틸화도의 측정 및 특성분석 = 60
• 4.4. 키틴 나노섬유의 생분해 및 생체적합성 측정 = 72
• Ⅴ. 결론 = 81
• 참고문헌 = 83
• ABSTRACT = 86