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Polikaprolakton (PCL) tıbbi alanda olası birçok uygulaması bulunan biyouyumlu alifatik bir poliesterdir. Bu çalışmada farklı özelliklere sahip ikili çözücü sistemleri kullanılarak, çözücü kaynaklı olmayan faz ayırma mekanizması yolu ile elektrik alan lif çekimi yönteminde gözenekli PCL lifleri üretilmiştir. Tekli ve ikili çözücü sistemlerinin lif boyutu ve yüzey morfolojisi üzerindeki etkisi araştırılmıştır. Diklorometan (DCM), lif yüzeyinde gözenekler oluşturmak için zayıf bir çözücü olan dimetil sülfoksit (DMSO) ile karışımlarda iyi bir çözücü olarak kullanılmıştır. Nano lif oluşumuna polimer konsantrasyonlarının (%12, %14 ve %16) w/v ve çözücü oranlarının (9:1, 7:3 ve 5:5) v/v etkisi araştırılmıştır. Elektrik alan ile lif çekimimde akış hızı 0,12mL/h, iğne ile kolektör arasındaki mesafe 15cm ve uygulanan voltaj 12kV olarak seçilmiştir. SEM fotoğrafları, farklı çözücüler ile PCL nanoliflerinin başarılı bir şekilde üretildiğini göstermiştir. Polimer konsantrasyonunun arttırılması ve çözücü oranlarının değiştirilmesi ile gözenekli PCL nanolifler üretilmiştir. İkili çözücü sistemlerinde %16 PCL polimerleri ve (7:3) % çözücü oranlı çözelti ile düzgün, boncuksuz, pürüzsüz ve gözenekli PCL lifler üretilebilmiştir. PCL matrisinin kendine has özelliklerini nano lifli matların karakteristiğiyle birleştirmek, biyomedikal uygulamalar dahil olmak üzere farklı uygulamalar için uygun olabilecek umut verici malzemelerin üretimi ile sonuçlanmıştır.Nanolifli yapıların geniş yüzey alanı, küçük gözenek çapı ve yüksek gözeneklilik gibi özellikleri içeren avantajları bu lifleri farklı uygulamalarda ilgi odağı haline getirmektedir. Elektrik alan lif çekimi ile üretilmiş gözenekli lifler hücre geliştirme için daha iyi bir alternatifdir., Polycaprolactone (PCL) is biocompatible aliphatic polyester with many possible applications in the medical field. Porous electrospun Polycaprolactone (PCL) fibers were produced through a non-solvent induced phase separation mechanism, using binary solvent systems with different properties. The effect of single and binary solvent systems on the fiber size and surface morphology were investigated. Dichloromethane (DCM) was used as a good solvent in mixtures with a poor solvent, dimethyl sulfoxide (DMSO), in order generate to pores on the fiber surface. The effect of polymer concentrations (12%, 14% and 16%) w/v and solvents ratios (9:1, 7:3 and 5:5) v/v were investigated on nanofiber formation. During electrospun fiber production, the flow rate was 0.12mL/h, the distance between needle and collector was 15cm and the applied voltage was 12kV. SEM micrographs showed successfull production of PCL nanofibers with different solvents. With increasing the polymer concentration and changing the ratio of the solvents porous PCL electrospun nanofiber was produced. In binary solvent systems 16% PCL polymers and (7:3) % solvents ratio solution make even, beads free, smooth and porous PCL electrospun fiber. Combining the inherent properties of the PCL matrix with the characteristic of nanofibrous mats, result in promising materials that can be suitable for different applications, including biomedical applications. The advantages of nanofibrous structures include large surface area, small diameter of pores and high porosity, which make them of great interest in different applications. Porous electrospun fiber is better for cell development.

Nanofibrils derived from natural biopolymers have received extensive interest due to their exceptional mechanical properties and excellent biocompatibility. To fabricate biocompatible chitosan nanocomposites with high mechanical performance, silkworm silks were deconstructed into nanofibrils as structural and mechanical reinforcement of chitosan. After dispersing silk nanofibrils in chitosan solution, a set of nanocomposites, including film, porous scaffold, filament, and nanofibrous sponge, could be fabricated from the blended solutions. Silk nanofibrils could be uniformly dispersed in chitosan solution, and formed multi-dimensional nanocomposites. The nanocomposites exhibited enhanced mechanical strength and thermal stability, and provided a biomimetic nanofibrous structure for biomaterial applications. The enhancement in mechanical properties can be attributed to the interaction between the nanofibril phase and the chitosan matrix. As the polysaccharide/protein bionanocomposites derived from natural biopolymers, these materials offer new opportunities for biomaterial application by virtue of their biocompatibility and biodegradability, as well as enhanced mechanical properties and controllable mesoscopic structure.

Silk fibroin (SF) hydrogels are explored for diverse applications, ranging from cosmetic thickeners to support matrices for drug delivery and regenerative medicine. However, their utilities remain inherent challenges in inadequate mechanical properties and sophisticated process. Hyaluronic acid (HA) is a natural polysaccharide with outstanding physiological activities and superior water retaining capacity. In this study, HA was used as a skeleton of interpenetrating network to fabricate SF/HA hydrogel with high-flexibility and micro or nanofibers networks. The flexibility and water-absorbing quality of SF/HA hydrogels are improved dramatically due to super hydrophilicity of HA addition. By the synergistic effect of HA and solvent exchange, SF molecular conformation is induced efficiently to form β-sheet structures and assembling directly by physical crosslinking, which are determined by structure analysis. Moreover, the condense structure of the SF/HA hydrogel is mainly silk II, which contributes to their high thermal stability. The HA also plays a dominating role in formation of the micro or nanofibers networks on the wall of the SF/HA hydrogels, confirming by elements analysis. Investigation on fibroblast vitality and morphology showed that these SF/HA hydrogels can support cell adhesion, differentiation, and proliferation in vitro and present a better biocompatibility in comparison to pure SF hydrogel. Thus, it is believed that this work provides a facile way to fabricate protein-polysaccharide biomaterials and tissue engineering scaffolds.

この博士論文は、次の学術雑誌論文を一部に使用しています。 / JAPANESE JOURNAL OF APPLIED PHYSICS. 51(1):01AK03 (2012); doi:10.1143/JJAP.51.01AK03. © 2012 The Japan Society of Applied Physics. / POLYMER COMPOSITES. 34(6):953-958 (2013); doi:10.1002/pc.22501. / ADVANCED MATERIALS RESEARCH. 796:301-305 (2013); doi:10.4028/www.scientific.net/AMR.796.301. © 2013 Trans Tech Publications, Switzerland. / REINFORCED PLASTICS. 59:6-9 (2013), Thesis, XU ANCHANG. On the molding method and the mechanical properties of advanced composite materials （先進複合材料の成形とその力学特性）. 信州大学, 2014, 博士論文. 博士（工学）, 甲第597号, 平成26年3月20日授与.