Mechanical Properties of Hydrated Silk Fibroin/Bacterial Cellulose Composite Films

정리라,김예슬,진형준,Jung, Ri-Ra,Kim, Ye-Seul,Jin, Hyoung-Joon The Korean Fiber Society 2007 한국섬유공학회지 Vol.44 No.3

Composite films consisting of two biocompatible natural polymers were prepared by incorporating bacterial cellulose into silk fibroin. The high crystalline cellulose hydrogel was synthesized by bacteria, Acetobacter xylinum. Silk fibroin was finely blended with the bacterial cellulose fibrils by adding aqueous silk fibroin solution into the bacterial cellulose hydrogel. We observed individual bacterial cellulose fibrils within a silk fibroin matrix by field emission scanning electron microscopy. The silk fibroin well penetrated between the individual fibrils of the bacterial cellulose. The silk fibroin/bacterial cellulose composite film did not dissolve in water without further crystallization process, whereas a pure silk fibroin film easily dissolved in water without crystallization process. The crystallization phenomenon of silk fibroin in the composite film was verified by X-ray diffraction and Fourier transform-infrared spectroscopy. Furthermore, the mechanical properties of the silk fibroin/bacterial cellulose composite film markedly increased when the composite film was hydrated. The silk fibroin/bacterial cellulose composite films became more flexible and tougher when they were hydrated, while it was very brittle in the dehydrated state.

Wafer-Scale Multilayer Fabrication for Silk Fibroin-Based Microelectronics

Kook, Geon,Jeong, Sohyeon,Kim, So Hyun,Kim, Mi Kyung,Lee, Sungwoo,Cho, Il-Joo,Choi, Nakwon,Lee, Hyunjoo J. American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.1

<P>Silk fibroin is an excellent candidate for biomedical implantable devices because of its biocompatibility, controllable biodegradability, solution processability, flexibility, and transparency. Thus, fibroin has been widely explored in biomedical applications as biodegradable films as well as functional microstructures. Although there exists a large number of patterning methods for fibroin thin films, multilayer micropatterning of fibroin films interleaved with metal layers still remains a challenge. Herein, we report a new wafer-scale multilayer microfabrication process named aluminum hard mask on silk fibroin (AMoS), which is capable of micropatterning multiple layers composed of both fibroin and inorganic materials (e.g., metal and dielectrics) with high-precision microscale alignment. To the best of our knowledge, our AMoS process is the first demonstration of wafer-scale multilayer processing of both silk fibroin and metal micropatterns. In the AMoS process, aluminum deposited on fibroin is first micropatterned using conventional ultraviolet (UV) photolithography, and the patterned aluminum layer is then used as a mask to pattern fibroin underneath. We demonstrate the versatility of our fabrication process by fabricating fibroin microstructures with different dimensions, passive electronic components composed of both fibroin and metal layers, and functional fibroin microstructures for drug delivery. Furthermore, because one of the crucial advantages of fibroin is biocompatibility, we assess the biocompatibility of our fabrication process through the culture of highly susceptible primary neurons. Because the AMoS process utilizes conventional UV photolithography, the principal advantages of our process are multilayer fabrication with high-precision alignment, high resolution, wafer-scale large area processing, no requirement for chemical modification of the protein, and high throughput and thus low cost, all of which have not been feasible with silk fibroin. Therefore, the proposed fabrication method is a promising candidate for batch fabrication of functional fibroin microelectronics (e.g., memristors and organic thin film transistors) for next-generation implantable biomedical applications.</P> [FIG OMISSION]</BR>

Silk fibroin/collagen protein hybrid cell-encapsulating hydrogels with tunable gelation and improved physical and biological properties

Buitrago, Jennifer O.,Patel, Kapil D.,El-Fiqi, Ahmed,Lee, Jung-Hwan,Kundu, Banani,Lee, Hae-Hyoung,Kim, Hae-Won Elsevier 2018 ACTA BIOMATERIALIA Vol.69 No.-

<P><B>Abstract</B></P> <P>Cell encapsulating hydrogels with tunable mechanical and biological properties are of special importance for cell delivery and tissue engineering. Silk fibroin and collagen, two typical important biological proteins, are considered potential as cell culture hydrogels. However, both have been used individually, with limited properties (<I>e.g.,</I> collagen has poor mechanical properties and cell-mediated shrinkage, and silk fibroin from <I>Bombyx mori (mulberry)</I> lacks cell adhesion motifs). Therefore, the combination of them is considered to achieve improved mechanical and biological properties with respect to individual hydrogels. Here, we show that the cell-encapsulating hydrogels of mulberry silk fibroin / collagen are implementable over a wide range of compositions, enabled simply by combining the different gelation mechanisms. Not only the gelation reaction but also the structural characteristics, consequently, the mechanical properties and cellular behaviors are accelerated significantly by the silk fibroin / collagen hybrid hydrogel approach. Of note, the mechanical and biological properties are tunable to represent the combined merits of individual proteins. The shear storage modulus is tailored to range from 0.1 to 20 kPa along the iso-compositional line, which is considered to cover the matrix stiffness of soft-to-hard tissues. In particular, the silk fibroin / collagen hydrogels are highly elastic, exhibiting excellent resistance to permanent deformation under different modes of stress; without being collapsed or water-squeezed out (<I>vs.</I> not possible in individual proteins) – which results from the mechanical synergism of interpenetrating networks of both proteins. Furthermore, the role of collagen protein component in the hybrid hydrogels provides adhesive sites to cells, stimulating anchorage and spreading significantly with respect to mulberry silk fibroin gel, which lacks cell adhesion motifs. The silk fibroin / collagen hydrogels can encapsulate cells while preserving the viability and growth over a long 3D culture period. Our findings demonstrate that the silk / collagen hydrogels possess physical and biological properties tunable and significantly improved (<I>vs.</I> the individual protein gels), implying their potential uses for cell delivery and tissue engineering.</P> <P><B>Statement of Significance</B></P> <P>Development of cell encapsulating hydrogels with excellent physical and biological properties is important for the cell delivery and cell-based tissue engineering. Here we communicate for the first time the novel protein composite hydrogels comprised of ‘Silk’ and ‘Collagen’ and report their outstanding physical, mechanical and biological properties that are not readily achievable with individual protein hydrogels. The properties include i) gelation accelerated over a wide range of compositions, ii) stiffness levels covering 0.1 kPa to 20 kPa that mimic those of soft-to-hard tissues, iii) excellent elastic behaviors under various stress modes (bending, twisting, stretching, and compression), iv) high resistance to cell-mediated gel contraction, v) rapid anchorage and spreading of cells, and vi) cell encapsulation ability with a long-term survivability. These results come from the synergism of individual proteins of alpha-helix and beta-sheet structured networks. We consider the current elastic cell-encapsulating hydrogels of silk-collagen can be potentially useful for the cell delivery and tissue engineering in a wide spectrum of soft-to-hard tissues.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

키토산과 견사 단백질 복합체의 특성

김희숙,원용돈,류병호 한국식품영양학회 1996 韓國食品營養學會誌 Vol.9 No.4

기능성 다이어트 식품을 개발을 목적으로, 키토산과 견 피브로인의 복합체를 만들고 성질을 조사하였다. 키토산은 대동새우로부터 추출하였고, 견사 피브로인 섬유는 누에로부터 추출하였다. 견사의 특성을 알아보기 위하여 용해도를 조사한 결과, 용해도는 8M LiBr이상의 농도와 40℃ 이상에서 가장 높았다. 견사 피브로인의 아미노산 조성은 천연견사 및 용해시킨 피브로인과 같았다. 키토산, 견사 피브로인 복합체의 아미노산 조성은 glycine, alanine, serine, tyrosine, threonine 및 glutamic acid 순서를 많았다. 또한 IR 스펙트럼 결과, 키토산·견사 피브로인 복합체는 배합비율에 따른 스텍트럼상의 차이는 거의 없었다. In order to develop the functional diet food, characteristics of chitosan and silk fibroin composite was designed. Chitosan extracted from a prawn and silk fibroin was prepared from silkworm. The silk fibroin was dissolved rapidly in the 8M LiBr at a temperatrue of more than 40℃. Amino acid composition of fibroin composite revealed the same pattern that of native silk fibroin and regenerated silk fibroin. Predominant amino acid of chitosan-fibroin composite contained glycine, alanine, serine, tyrosine, threonine, and glutamic acid in order. According to the basis on the infrared spectrum, chitosan-silk fibroin composite is not distinguished differents composite ratio of chitosan and silk fibroin.

Effects of silk fibroin hydrolysate on bone metabolism in ovariectomized rats

( Hae Yong Kweon ),( Sun Hee Shin ),( Jeong Woo Chon ),( Kwang Gill Lee ),( You Young Jo ),( Ji Young Yoon ),( Yoo Kyoung Park ),( Jong Young Jeon ),( Jong Ho Kim ),( Bong Seob Shin ) 한국잠사학회 2015 International Journal of Industrial Entomology Vol.30 No.1

This study aimed to investigate the effects of silk fibroin on bone metabolism in ovariectomized rats. A total of 30 Sprague-Dawley rats were randomized into sham-operated (SHAM), ovariectomized control (OVX), alendronate (OVX+ALEN, 10 mg/kg body weight/d), low silk fibroin (OVX+SF100, 100 mg/kg body weight/d), and high silk fibroin (OVX+SF300, 300 mg/kg body weight/d) groups. All the rats were fed by gavage for 12 wk. At the end of 12 wk, blood and urine were collected for analysis of bone turnover markers, and bone mineral density (BMD) was measured by micro-computed tomography. The results show that the OVX group (p < 0.05) displayed the highest mean body weight gain. Among the five groups, serum levels of bone alkaline phosphatase (ALP) and urine levels of deoxypyridinoline (DPD) were highest in the OVX group (p < 0.05). Bone ALP levels in the ALEN group were significantly lower than that of the silk-treated groups. On the other hand, DPD levels were not significantly different between the ALEN and silk-fibroin-treated groups (p < 0.05). The trabecular BMD was significantly higher in the ALEN and silk-treated groups compared to the OVX group (p < 0.05). In conclusion, this study showed that silk fibroin has similar effects as alendronate, which is used in osteoporosis medication. Therefore silk fibroin might be a new candidate for the prevention and treatment of osteoporosis in patients.

혼합 실크 피브로인막의 투명도

조유영 ( You Young Jo ),권해용 ( Hae Yong Kweon ),여주홍 ( Joo Hong Yeo ),이광길 ( Kwang Gill Lee ) 한국잠사학회 2013 한국잠사곤충학회지 Vol.51 No.2

Silk fibroin is a natural biomaterial that has the biocompatibility and other many advantages. But as a silk fibroin membrane thickness increases, the transparency becomes more opaque. Because the transparency of membranes tissue such as the cornea and dura mater are necessary, transparent membrane is required to replace these transparent membranes. In this study, we fabricated blending silk fibroin membranes that made by mixing the various inorganic salts or polymer in an aqueous solution of silk fibroin. The transparency of the membranes were analyzed. the transparency of these membranes is very different, depending on the mixed materials. Inorganic salts mixed silk membrane was more transparent than the polymer mixed one. Especially, the silk fibroin membrane with calcium chloride was very transparent. We showed the possibility of blending silk fibroin membrane, which can be used in perfect transparent membrane such as the cornea. In the future, we expect that the transparent blending silk fibroin membrane can be used in various medical applications.

실크 피브로인 지지체와 Substance P를 이용한 골 이식재

박기유,최교희,박영주,송지영,김성곤,조유영,권해용,강석우,Park, Ki-Yu,Choi, Kyo-Hee,Park, Young-Ju,Song, Ji-Young,Kim, Seong-Gon,Jo, You-Young,Kweon, Hae-Yong,Kang, Seok-Woo 대한악안면성형재건외과학회 2011 Maxillofacial Plastic Reconstructive Surgery Vol.33 No.4

Purpose: Substance P is a well known neurotransmitter and has been known to mediate pain. Recently, it has been unveiled that substance P is involved in the recruitment of mesenchymal stem cells to wound sites. The purpose of this study was to exam bone formation when a combination of substance P and silk fibroin was used in a bone defect model. Methods: Twenty rabbits were used and 40 calvarial defects were formed. They were divided as 4 groups (unfilled control, silk only, silk+$10{\mu}g$/ml substance P; Sub10, and silk+$100{\mu}g$/ml substance P; Sub100). All animals were humanely sacrificed 4 or 8 weeks after grafting. The specimens were analyzed by micro-computerized tomography and histological analysis. Results: When compared to the unfilled control to silk only group, there was significant difference in bone mineral density (BMD) and the attenuation coefficient (AC) at 4 weeks ($p$=0.037 and 0.038, respectively). When compared Sub10 group to Sub100 group, there was significant difference in BMD and AC at 8 weeks ($p$=0.004 for all). Residual graft amounts were $52.1{\pm}15.8$%, $15.2{\pm}9.2$% and $9.0{\pm}3.3$% for silk only, Sub10, and Sub100 groups, respectively. When comparing the residual graft amount of silk only to sub10 or sub100, the differences were statistically significant ($p$ <0.001). Conclusion: The silk fibroin scaffold showed higher BMD and AC than the unfilled control. The combination graft with substance P and silk fibroin scaffold showed a faster graft degradation than with a silk fibroin scaffold only.

Effects of silk fibroin hydrolysate on bone metabolism in ovariectomized rats

Kweon, HaeYong,Shin, Sun Hee,Chon, Jeong-Woo,Lee, Kwang-Gill,Jo, You-Young,Yoon, Ji Young,Park, Yoo-Kyoung,Jeon, Jong-Young,Kim, Jong-Ho,Shin, Bong-Seob Korean Society of Sericultural Science 2015 International Journal of Industrial Entomology Vol.30 No.1

This study aimed to investigate the effects of silk fibroin on bone metabolism in ovariectomized rats. A total of 30 Sprague-Dawley rats were randomized into sham-operated (SHAM), ovariectomized control (OVX), alendronate (OVX+ALEN, 10 mg/kg body weight/d), low silk fibroin (OVX+SF100, 100 mg/kg body weight/d), and high silk fibroin (OVX+SF300, 300 mg/kg body weight/d) groups. All the rats were fed by gavage for 12 wk. At the end of 12 wk, blood and urine were collected for analysis of bone turnover markers, and bone mineral density (BMD) was measured by micro-computed tomography. The results show that the OVX group (p < 0.05) displayed the highest mean body weight gain. Among the five groups, serum levels of bone alkaline phosphatase (ALP) and urine levels of deoxypyridinoline (DPD) were highest in the OVX group (p < 0.05). Bone ALP levels in the ALEN group were significantly lower than that of the silk-treated groups. On the other hand, DPD levels were not significantly different between the ALEN and silk-fibroin-treated groups (p < 0.05). The trabecular BMD was significantly higher in the ALEN and silk-treated groups compared to the OVX group (p < 0.05). In conclusion, this study showed that silk fibroin has similar effects as alendronate, which is used in osteoporosis medication. Therefore silk fibroin might be a new candidate for the prevention and treatment of osteoporosis in patients.

Bacillus licheniformis 단백질 분해 효소에 의한 정연 견사의 특성 I. 정연 견사의 이화학적 특성

김영대,남중희 한국잠사학회 1992 한국잠사곤충학회지 Vol.34 No.2

견사의 정연 방법으로는 알카리 용액에서 열을 이용하는 방법과 단백질 분해 효소를 이용하는 방법으로 크게 나눌 수 있는데 본 실험은 Bacillus licheniformis 단백질 분해 효소로 정연한 견사의 이화학적 특성과 열 처리 영향 및 효소 정연 견 피브로인 수용액의 특성을 비누 정연 견사와 비교하여 실험한 결과 다음과 같은 결과를 얻었다. 1. 정연 견사의 표면을 주사 전자현미경으로 관찰한 결과 정연 방법에 따른 뚜렷한 차이가 없었으며 정연 견사의 아미노산 조성을 분석한 결과에서도 정연 방법에 따른 큰 차이가 없었다. 2. 효소 정연 견사는 비누 정연 견사에 비하여 강력과 신도가 약간 저하되었고 점도도 비누 정연 견사의 0.59에 비하여 효소 정연 견사는 0.56으로서 저하된 반면 ($\alpha$+$\varepsilon$) amino group content는 비누 정연견사의 49.5$\mu$mo1/g보다 효소 정연 견사는 53.6 $\mu$mol/g로서 증가되었으므로 효소 정연 견사는 비누 정연 견사보다 degradation이 더 일어난 것으로 추측된다. 3. 효소 정연 견사는 비누 정연 견사에 비하여 복굴절도가 높았으며 DSC thermogram에서 열 분해 온도도 약 1$0^{\circ}C$ 높았다. 또 효소 정연 견사의 IR 및 X-ray crystallinity도 각각 0.70과 0.53으로서 비누정연 견사의 0.67과 0.50에 비하여 약간 높았으므로 효소 정연 견사의 경우 결정성 및 배향성이 비누 정연 견사보다 높은 것으로 판단된다. In this thesis, both soap and enzymatic degumming method were adopted and the optimum degumming conditions were obtained. Difference between the two degumming methods in silk fiber state was investigated and analyzed on the basis of the results of physical testings, polarizing microscopy, scanning electron microscopy, viscosity measurement, (${\alpha}$+$\varepsilon$) amino group contents measurement, birefringence measurement, amino acid analysis, thermal analysis, infrared spectroscopy and x-ray diffraction analysis. The results obtained were summarized as follows; Physical test results of the degummed silk fiber showed that the tenacity and the elongation of enzymatic degummed silk fiber were lower than those of soap degummed fiber. But SEM observation and amino acid analysis showed almost the same tendency in the two degumming methods. The viscosity of enzymatic degummed silk fiber was lower than that of soap degummed fiber, but (${\alpha}$+$\varepsilon$) amino group contents was higher in the enzymatic degummed fiber. It can be suggested that the enzymatic degummed silk fibroin was more degraded than the soap degummed fibroin. The birefringence, endothermic temperature of DSC spectrum, IR crystallinity and X-ray lateral order factor of enzymatic degummed silk fiber were higher than those of soap degummed fiber. It seems that the enzymatic degummed silk fiber has the higher crystallinity than that of soap degummed one according to the above results. However, it can be inferred that these differences between soap and enzymatic degummed fiber would be lessened if pretreatment and aftertreatment were included in the enzymatic degumming process.

NF-κB signaling is key in the wound healing processes of silk fibroin

Park, Ye Ri,Sultan, Md. Tipu,Park, Hyun Jung,Lee, Jung Min,Ju, Hyung Woo,Lee, Ok Joo,Lee, Dong Jin,Kaplan, David L.,Park, Chan Hum Elsevier Science B.V. Amsterdam 2018 ACTA BIOMATERIALIA Vol. No.

<P><B>Abstract</B></P> <P>Silk fibroin (SF) is a well-studied biomaterial for tissue engineering applications including wound healing. However, the signaling mechanisms underlying the impact of SF on this phenomenon have not been determined. In this study, through microarray analysis, regulatory genes of NF-ĸB signaling were activated in SF-treated NIH3T3 cells along with other genes. Immunoblot analysis confirmed the activation of the NF-ĸB signaling pathway as SF induced protein expression levels of IKKα, IKKβ, p65, and the degradation of IκBα. The treatment of NIH3T3 cells with SF also increased the expression of cyclin D1, vimentin, fibronectin, and vascular endothelial growth factor (VEGF). The expression of these factors by SF treatment was abrogated when NF-ĸB was inhibited by a pharmacological inhibitor Bay 11-7082. Knockdown of NF-ĸB using siRNA of IKKα and IKKβ also inhibited the SF-induced wound healing response of the NIH3T3 cells in a wound scratch assay. Collectively, these results indicated that SF-induced wound healing through the canonical NF-κB signaling pathway via regulation of the expression of cyclin D1, vimentin, fibronectin, and VEGF by NIH3T3 cells. Using an <I>in vivo</I> study with a partial-thickness excision wound in rats we demonstrated that SF-induced wound healing via NF-κB regulated proteins including cyclin D1, fibronectin, and VEGF. The <I>in vitro</I> and <I>in vivo</I> data suggested that SF induced wound healing via modulation of NF-ĸB signaling regulated proteins.</P> <P><B>Statement of Significance</B></P> <P>Silk fibroin has been effectively used as a dressing for wound treatment for more than a century. However, mechanistic insight into the basis for wound healing via silk fibroin has not been elucidated. Here we report a key mechanism involved in silk fibroin induced wound healing both <I>in vitro</I> and <I>in vivo.</I> Using genetic- and protein-level analyses, NF-κB signaling was found to regulate silk fibroin-induced wound healing by modulating target proteins. Thus, the NF-κB signaling pathway may be utilized as a therapeutic target during the formulation of silk fibroin-based biomaterials for wound healing and tissue engineering.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>