견 피브로인 나노섬유의 제조 및 특성분석

김소현 忠南大學校 大學院 2002 국내석사

Recently, much attention has been paid to electrospinning process as a unique technique because it can produce polymer nanofibers with diameter in the range from several micrometer down to tens of nanometers, depending on the polymer and processing conditions. In electrospinning, a high voltage is applied to create electrically charged jets of a polymer solution. These jets dry to form nanofibers, which are collected on a target as a nonwoven fabric. 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, sensing applications. An electrospinning process was used to fabricate silk fibroin (SF) nanofiber nonwovens for wound dressing applications. The electrospinning of regenerated SF was performed with formic acid as a spinning solvent. For crystallization, as-spun SF nanofiber nonwovens were chemically treated with an aqueous methanol solution of 50%. The morphology, porosity and conformational structures of as-spun and chemically treated SF nanofibers were investigated by scanning electron microscopy (SEM), mercury porosimetry, wide angle X-ray diffraction (WAXD), attenuated total reflectance infrared spectroscopy,(ATR-IR), solid-state ^(13)C CP/MAS nuclear magnetic resonance (NMR) spectroscopy, SEM micrograph showed that the electrospun SF nanofibers had an average diameter of 80nm and a distribution in diameter ranging from 30 to 120nm. The porosity of as-spun SF nanofiber nonwovens was 75.1 %, indicating it was highly porous. During the chemical treatment for 60 min, porosity of nonwovens composed of SF nanofibers decreased of to 68.1%. Conformational transitions of the as-spun SF nanofibers from random coil to β -sheet by aqueous methanol treatment occurred rapidly within 10 min, confirmed by solid-state ^(13)C CP/MAS NMR, ATR-IR and X-ray diffraction. To assay the cytocompatibility and cell behavior onto the electrospun SF nanofibers, cell attachment of norma1 human keratinocytes seeded on the SF nanofibers and interaction between cells and SF nanofibers were studied. Cell morphology on SF nanofibers was examined by scanning electron microscopy. Our results indicate that the SF nanofibers may be a good candidate for the biomedical applications, such as wound dressing and scaffolds for tissue engineering.

Structural characterization and biomedical application of electrospun silk fibroin nanofibers

남영식 忠南大學校 2004 국내박사

전기방사를 통하여 견 피브로인의 나노 섬유 집합체를 얻고 의료용 전개를 위하여 세포 배양 지지체로의 성능을 평가하였다. 전기방사를 통하여 기존의 방사법으로 얻어지는 섬유에 비해 수십 배에서 수백 배나 가는 섬유를 얻을 수 있다. 그 결과 비표면적이 매우 큰 나노 섬유를 제조할 수 있고 이렇게 제조된 나노 섬유는 필터류나 방호복 등에 적용될 수 있고 특히 일반적인 세포 크기보다 섬유 직경이 적어서 세포 배양에 적합한 용도를 가진다. 전기 방사는 비교적 간단한 장치를 이용하여 나노 섬유를 제조함과 동시에 부직포 형태의 섬유 집합체를 별도의 공정 없이 얻을 수 있는 방사법으로 극소량의 샘플만으로도 섬유를 제조할 수 있다. 재생 처리된 견 피브로인에 개미산(Formic Acid)을 방사 용제로 하여 전기방사를 하였고 방사된 견 피브로인의 물에 대한 용해성을 줄이기 위해 50% 메탄올 수용액으로 결정화 처리를 하였다. 견 피브로인 나노섬유는 주사 전자 형미경(SEM)을 통하여 형태학적 특징을 분석하였고 X선 회절(WAXD), 핵자기 공명분광(13C CP/MAS NMR) 및 표면 반사 적외선 분광(ATR-IR) 등으로 β-sheet 로의 구조변화를 관찰하였다. 인스트론을 통하여 견 피브로인 섬유 집합체의 물리적 특성을 측정하였고 견피브로인의 기공도 측정을 통하여 세포 배양체로서의 유용성을 알아보았으며 세포 점착능 및 세포 배양 실험을 실시하였다. 전기방사된 견 피브로인 나노 섬유는 원형 단면을 가지며 표면은 매끈하였다. 방사된 견 피브로인 나노 섬유는 랜덤 코일 형태를 가지고 있는데 비해 10분 정도 메탄올 수용액으로 처리할 경우 β-sheet 상으로 구조가 변하는 것을 확인할 수 있었다. 견 피브로인의 형태에 따른 세포 점착 및 배양 거동을 비교하기 위하여 마이크로 섬유상의 직포와 나노 섬유 집합체 및 필름형태의 견 피브로인을 제조하였다. 각각의 견피브로인 집합체의 구조적인 특성 및 세포친화성을 평가한 결과 필름이나 마이크로 섬유에 비해 나노 섬유 형태의 견 피브로인이 생의학적인 용도에 적합한 것을 알 수 있었다. 재생된 견 피브로인은 나노 섬유로 제조 시 물에 대한 용해도가 높아서 메탄올과 같은 유기용액으로 처리하여 결정화를 시켜주는 것이 일반적이다. 이 결과 섬유가 딱딱해지고 유연성이 부족하여 여러 가지 용도 전개에 어려움이 있었다. 이를 해결하기 위하여 메탄올처리 대신 수증기를 통한 화학적 처리를 통하여 물에 대한 안정성을 높이고 물리적 성질을 개선하였다. 세포점착 및 세포 배양 실험 결과로 따라서 견 피브로인 나노 섬유는 세포 배양 지지체나 창상용 봉합체 등의 의학적 용도로 전개하는데 적합하다는 것을 알 수 있었다. The electrospinning process makes fibers with diameters in a range one or two orders of magnitude smaller than those of conventional textile fibers. As a result, nanofibers with large specific surface area are produced and can be applied for filtration and protective clothing. Especially the small diameters of nanofibers compared to that of cells can make it possible to promote cell culturing well. By electrospinning nanofibers matrix like nonwoven type can be obtained simultaneously, in a single step, with relatively simple equipment and the only small amount of polymer sample is needed for electrospinning. The electrospun silk fibroin(SF) nanofibers had an average diameter of 80nm and their diameters ranged from 30nm to 120nm having a circular cross-section with a smooth surface. The as-spun SF nanofibers prepared from formic acid solution was mainly consisted of random coil conformation. And the conformational change from random coil to β-sheet structure was induced by methanol treatment within 10 minutes. To assay the cytocompatibility and cell behavior onto the electrospun SF nanofibers, cell attachment and spreading of normal human keratinocytes and fibroblasts seeded on the SF nanofibers and interaction between cells and SF nanofibers were studied. SF nanofiber matrix had a wide range of pore size distribution and high porosity. Type I collagen coated silk fibroin nanofibers promoted well the adhesion of proliferating NHOK and NHEK. In open wound healing test, silk fibroin nanofiber matrix promotes as early stage of wound healing rather than cotton gauze in the experimental animals. In the cell activity assessment, the SF nanofiber matrix was found to promote cell adhesion and spreading better than SF microfiber matrix and SF film matrix because SF nanofiber matrix provides a higher level of surface area for cells to attach due to its high porosity and surface area-to-volume ratio. The insolubility in water was obtained both cases of water-vapour treatment and methanol treatment. And the water-vapour treated SF fibers were more flexible than methanol treated SF. In water-vapour treatment reaction, the conformational transition to β-sheet occurred the same as in case of methanol treatment. And water-vapour treated SF nanofibers was found to promote adhesion and spreading for NHEF than methanol treated SF nanofibers. Our results indicate that the SF nanofiber matrix may be a better candidate than SF film and SF microfiber matrices for biomedical applications, such as wound dressings and scaffolds for tissue engineering.

Preparation and characterization of TiO2 composite nanofibers by electrospinning and their photocatalytic activity

리강 忠南大學校 大學院 2009 국내박사

최근에 환경보호에 대한 의식이 높아짐에 따라 TiO2 광촉매는 큰 각광을 받고 있다. 그러나 anatase 결정구조를 가지는 TiO2의 밴드갭이 3.2eV이므로 자외선조사(<390nm) 에 의해서만 광촉매활성을 나타낸다. 그러므로 태양광 혹은 일반 램프의 조사조건에서 광촉매효율을 높이기 위해서는 반드시 밴드갭을 줄여야 한다. 질소도핑은 질소의 2p와 산소의 2p를 믹싱함으로써 밴드갭이 줄어든 질소가 도핑 된 TiO2를 제조할 수 있으며 가시광선을 조사하여도 광촉매특성이 쉽게 활성된다. 전기방사방법은 폴리머, 세라믹 혹은 복합나노섬유를 제조하는데 있어서 아주 심플하고도 간편한 제조방법으로서 직경이 균일하고 몇십나노미터에서 몇마이크로미터에 달하는 섬유를 제조할 수 있다. 최근에 많은 연구자들이 전기방사방법으로 나노구조를 가지는 다양한 TiO2 복합박막 혹은 나노섬유를 제조하고 있다. 나노알갱이들은 agglomerate 혹은 클러스터를 형성하는 경향이 있으므로 “나노효과”로 쉽게 응집되어 제조과정이 복합하고 복합나노섬유를 얻기 힘들며 광촉매활성이 떨어진다. 본 논문에서는 전기방사방법으로 TiO2/폴리머 형태의 복합나노섬유를 제조하여 광촉매활성을 평가하였다. 우선, as-spun 나노섬유를 제조하기 위하여 복합섬유의 형상과 특성에 영향을 주는 공정변수들인 TiO2와 폴리머의 혼합비율, hybrid sol에서의 폴리머의 농도, 인가전압, 주사기팁부터 collector까지의 거리 (TCD) 등 변수들에 대해 분석하였다. 다음으로 asspun 섬유를 가수분해, 열처리, 질소도핑, 고온에서의 탄화처리를 거쳐 anatase TiO2/폴리머, 질소를 도핑한 TiO2/PAN 나노섬유, TiO2/carbon 나노섬유를 제조하여 주사전자현미경, x선회절, ATR-IR 스펙트럼, TGA-DTA, 광촉매활성 등 특성을 연구분석하여 다음의 결론을 얻었다. Anatase TiO2/폴리머 나노섬유의 평균 직경은 600~850nm이다. XRD패턴으로부터 TiO2복합나노섬유는 anatase 혹은 rutile 구조를 가짐을 알 수 있었다. 또한 TiO2/폴리머 복합나노섬유는 다양한 처리를 거쳐 MG dye 의 photodegradation 실험으로부터 자외선조사뿐만 아니라 가시광선을 조사하여도 좋은 광촉매활성을 나타냈다.

은을 함유한 셀룰로스 아세테이트 나노섬유의 제조 및 특성분석

장기혁 忠南大學校 大學院 2009 국내석사

Poly(3-hydroxybutyrate) 필름 및 나노섬유의 구조ㆍ물성에 미치는 첨가제의 영향

최재신 忠南大學校 大學院 2002 국내석사

Poly(3-hydroxybutyrate) (PHB), which is biosynthesized by a wide variety of bacteria, is a biodegradable thermoplastic with biocompatibility and ecological safety. Therefore, it has much potential in applications such as surgical sutures, longterm carriers for drugs, ana degradable plastics. However, until now there is no a larger commercial products because PHB has the higher cost, narrow processability window and brittleness, compared to commercial synthetic polymers. These drawbacks in PHB call be overcome by internal or external plasticization to improve impact strength elongation at break and ductility. From many attempts for the internal plasticization of PHB, various copolymers with 3-hydroxyvalerate, 4-hydroxybutyrate, and 3-hydroxyalkanote units have been developed using the bacteria 1 fermentation method. These copolymers have improved physical and mechanical properties, compared to PHB homopolymer. On the other hand, the external plasticization is more efficient to apply to polymers because it could provide a relatively simple route to improve some mechanical properties of polymer as well as a lower cost for products. However, plasticizers for biodegradable polymers should preferably also be biodegradable. In this respect, most of plasticizers used in synthetic polymer processing are not suitable for PHB. There was only a few reports on the external plasticization of PHB, though biodegradable plasticizers play an important role in the practical processing for soule applications such ar packaging materials. The objective of this study is to develop the appropriate plasticizer for improving the stiffness and thermal stability of PHB. We focused on the comparison of physical and mechanical properties of PHB blends, plasticized by biodegradable additives. Recently, the electroapinning method has attracted a great deal of attention to produce nos-woven membranes of nanofibers. Electrospinning was a process that produces containuous polymer fibers with diameters in the sub-micron range through the action of an external electric field imposed on a polymer solution or melt. The morphology of ultrafine fibers produced by electrospinning method strongly depends on the spinning conditions such as polymer concentration spinning distance, additive-type and volatility of solvent. The addition of additives to spinning solution could be expected to be an important parameter influencing the morphology of fiber collected on targer, because the additives change the physicochemical properties of polymer solution including the surface tension. The aim of this study is to investigate the effect of organosoluble electrolyte on the diameter of electrospun PHBV ultrafine fibers. The variation in polymer concentration spinning distance, ana electric field didn't show any signigicant effect on the average fiber diameter. However, the addition of benzyltriethylamminium chloride(BTEAC) to polymer solution caused a significant decrease of fiber diameter of PHBV fiber. In addition BTEAC caused significant variation of PHBV/chloroform solution properties. The electrical conductivity of the solution was increased by several order of magnitude by addition of BTEAC and the surface tension increased gradually with increasing amount o BTEAC, while no significant change was observed for tile solution viscosity.

키틴, 키토산 나노섬유의 제조및 특성 분석

이성원 忠南大學校 大學院 2006 국내석사

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.

파라계 아라미드 섬유의 열처리에 따른 구조 및 특성 분석

이민호 忠南大學校 大學院 2009 국내석사

The evolution of the mechanical properties and structure of poly(p-phenylene terephthalamide)(PPTA) fibers with different heat treatment methods involving temperature, tension was systematically investigated. After different heat treatments, their mechanical properties and structure were characterized. The cooperative changes in the modulus was related that the spinning process and heat treatment. Tensile modulus was increased with increase of the spinning rate and low denier value at the spinning process. And tensile strength and elongation were decreased with the increase of the heat treatment temperature, but modulus was increased. It was also tend to increase modulus with increase of the draw ratio. Structural characterization was carried out using wide angle X-ray scattering(WAXS). The structure parameters investigated include lattice constants, a, b, c; intensity ratio of the principal equatorial reflections, I110/I200; apparent crystal sizes (ACS) measured from the broadening of reflections from (004), (110) and (200) planes; and (200) orientation angle, Φ200 from azimuthal angle of (200) plane. After heat treatment, ACS and orientation was increase with increase of the temperature and draw ratio.

모노에탄올아민 전처리에 의한 양모섬유의 저온염색

하민자 忠南大學校 1987 국내석사

The dyeing properties of wool pretreated with monoethanolamine and neutralized with formic acid were investigated. The experiments were performed using Orange II(C.I.Acid Orange 7)for various temperatures(40˚, 50˚, 60℃) at pH 4.7. The results obtained were as follows: 1. The apparent diffusion coefficients of pretreated wool were larger than untreated wool. The increase of the apparent diffusion coefficient of pretreated wool is attributed to the removel of scale which is the surface barrier of dye diffusion. 2. The apparent activation energy of diffusion of pretreated and untreated wool were 19.7kcal/mole, 28.3kcal/mole, respectively. The temperature dependency of pretreated wool was smaller than that of untreated wool. 3. According to the dye absorption and dye exhaustion curve, the low temperature dyeing of pretreated wool might be possible at 50℃ for about 1 hour. 4. Equilibrium dye absorption on fiber, both of pretreated and untreated wool, reduced with increase of temperature. 5. The scale of wool was removed significantly by pretreatment as shown in scanning electron micrographs.

고분자/금속 계면 상호작용에 대한 분광학적 고찰

이원옥 忠南大學校 大學院 2003 국내석사

In this study, interfacial properties between polymers containing oxygen/nitrogen groups and metals are analyzed. In order to understand the interfacial interactions between polymer and metal, and to determine the extent of interaction, we used the X-ray photoelectron spectroscoy (XPS) and RAIR spectroscopy Adhesion behavior between Poly(ethylene-co-vinyl acetate) (EVA) and metals(aluminum, copper) are studied as a function of vinyl acetate (VAc) content. Also, we composed the adhesive strength of interface as a change of metal substrate, aluminum of copper. Interfacial adhesive strength of EVA/aluminum system and EVA/copper system increased with vinyl acetate content up to 18 mol% and then decreased. Because of the rubber-like properties of EVA over 18 mol% VAc, the adhesive strength depends not only on the interface but also on the film itself. The adhesive strength of EVA/aluminum system is slightly greater than that of EVA/copper system. It can be explained that the electronegativity of aluminum atom is smaller than that of copper atom. At the interfacial characterization, there is a large amount of the carbonyl C 1s peak in 75˚ incident angle than in 15˚ incident angle at the EVA/metal system At near the interface, the binding energy of carbonyl group carbon atom shifts to the low binding energy. In the case of area ratio between oxygen and carbon atoms, EVA/aluminum systems exhibit higher oxygen area ratio than EVA/copper systems. In RAIR spectroscopy, the absorption peak of carbonyl group shifts to the low energy region as the vinyl acetate content increase. This is the bonding energy of carbonyl group becomes weak because the oxygen atom interacts with metal. In the other study, we also analyzed the adhesive behavior between metals and polymers, poly(benzoxazole) (PBO) that can be used as a (이후원문누락)

Cellulose 纖維의 sillicone 撥水加工에 있어서 觸媒의 影響

심준택 충남대학교 대학원 1976 국내석사