Co-reporter:Lijuan Xu, Shufang Wang, Xiang Sui, Yu Wang, Yinan Su, Li Huang, Yunwei Zhang, Zheng Chen, Qianqian Chen, Haitao Du, Yaopeng Zhang, and Li Yan
ACS Applied Materials & Interfaces May 3, 2017 Volume 9(Issue 17) pp:14716-14716
Publication Date(Web):April 14, 2017
DOI:10.1021/acsami.7b02805
The main limitation of liver transplantation as a treatment for end-stage liver disease or acute liver failure is the scarcity of liver organ donors. To develop an alternative therapy for acute liver failure, mesenchymal stem cell (MSC)-seeded regenerated silk fibroin (RSF) matrices were evaluated in vitro and in vivo. Adipose-derived mesenchymal stem cells (ADSCs) and bone marrow-derived mesenchymal stem cells (BMSCs) were planted and grown on RSF scaffolds to form a scaffold complex. The RSF–MSC scaffold complex (the experimental group) and neat RSF scaffolds (the control group) were then placed onto the liver surface of mice induced by CCl4 and detected after 5, 7, 14, 28, and 60 days. The growth and distribution of MSCs were tracked using fluorescence microscopy and live small animal fluorescence. Liver functions were tested using an automatic biochemistry analyzer. The histological kinetics of RSF complex and liver tissues were observed using hematoxylin & eosin staining. We found that MSCs exhibited good biocompatibility with RSF and differentiated to hepatocyte-like cells in vitro. Liver functions of the mice in the experimental group were significantly improved than that in the control group. Moreover, angiogenesis and hepatocyte-like cells were discovered in the RSF scaffolds in an animal model of acute liver failure on the fifth day and in the second month, respectively. The MSCs–RSF matrices show an obvious therapeutic ability for injured liver function of mice, which is more efficient than the neat RSF scaffolds.Keywords: acute liver failure; biocompatibility; mesenchymal stem cells (MSCs); regenerated silk fibroin matrices; transplantation;
Co-reporter:Yatao Liu, Lixin Yin, Huirong Zhao, Guangkun Song, Fangming Tang, Lili Wang, Huili Shao, Yaopeng Zhang
Polymer 2017 Volume 119(Volume 119) pp:
Publication Date(Web):16 June 2017
DOI:10.1016/j.polymer.2017.05.032
•In situ SAXS and WAXD are performed on PET fiber during drawing at 20 and 200 °C.•The evolutions in crystalline, lamellar and fibrillar structures are analyzed based on the stress-strain curves.•Destruction of lamellar structure resulted from crystal fragmentation is observed during cold drawing.•During hot drawing, lamellar structure always exists, and crystallization and extension of amorphous molecules occur.In situ synchrotron small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD) were carried out to study the lamellar and crystalline structural evolutions of poly(ethylene terephthalate) (PET) fiber during cold (20 °C) and hot (200 °C) drawing. The stress-strain curves were divided into two zones, i.e. linearly stress developing zone (zone I) and yield zone around fracture (zone II). In zone I during cold drawing, the two-dimensional (2-D) SAXS pattern transformed from a four-spot pattern to the coexistence of two- and four-spot patterns. The disappearance of lamellar peaks in zone II indicated the destruction of periodic lamellar structures, which was caused by the surface fragmentation of crystalline layers. In contrast, the 2-D SAXS patterns always existed during hot drawing, and the lamellar inclination decreased with strains. The lamellar and fibrillar structures were not destroyed, and crystallization occurred in the interlamellar amorphous layers. Fragmentation of crystalline surface mostly occurred at the end of zone II near fracture process. WAXD data suggested that the crystallinity and crystallite size perpendicular to (010) plane decreased, while the crystallite size perpendicular to (100) plane was rather stable during both cold and hot drawing.Download high-res image (363KB)Download full-size image
Co-reporter:Dan Jiang, Jianwen Huang, Huili Shao, Xuechao Hu, Lujie Song, Yaopeng Zhang
Materials Science and Engineering: C 2017 Volume 77(Volume 77) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.msec.2017.03.222
•Inherent growth factors are quantitatively confirmed to preserve well in BAM hydrogel.•Bioactive factors in BAM hydrogels remain a high release amount for at least 16 days.•BAM hydrogels support the adherence and growth of porcine iliac endothelial cells.Bladder acellular matrix (BAM) hydrogel may have great potential in tissue engineering due to outstanding biocompatibility and the presence of inherent bioactive factors in BAM. In this study, we prepared the BAM hydrogel by the method of enzymatic solubilization with pepsin and characterize the microrheological properties of the BAM precursor solution. The structures of the BAM hydrogel were characterized by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Furthermore, the growth factors including vascular endothelial growth factor (VEGF), platelet-derived growth factor B (PDGF-BB), keratinocyte growth factor (KGF) were quantified by ELISA. The biological performances of the hydrogels were evaluated by cultivating porcine iliac endothelial cells (PIECs) in vitro. Lyophilized BAM showed porous structure with pore diameter ranging from 50 to 100 μm. BAM 4-G hydrogel (4 mg/mL) with a short gelation time of 3.95 ± 0.07 min presents better thermal stability than BAM 6-G hydrogel (6 mg/mL). Growth factors in the BAM hydrogel maintain valuable biological activity even after digestion process. The BAM hydrogel supported the adhesion and growth of PIECs well and has great potential for further tissue engineering.
Co-reporter:Chao Zhang;Jie Luo;Jingru Shi;Huili Shao;Xuechao Hu
RSC Advances (2011-Present) 2017 vol. 7(Issue 6) pp:3108-3116
Publication Date(Web):2017/01/04
DOI:10.1039/C6RA22544F
Graphene oxide (GO) with outstanding mechanical properties is a satisfactory filler to reinforce artificial silk. To prepare tough regenerated silk fibroin/graphene oxide (RSF/GO) hybrid fibers, it is important to understand the structural evolution of the hybrid fibers with external deformation. The morphology and microstructural changes of the hybrid fibers at different tensile strains were investigated by SEM, Raman spectra and synchrotron radiation wide angle X-ray diffraction (SR-WAXD). Longer and deeper stripes were found on the surface of RSF/GO fibers with the increase of strain as revealed by SEM. SR-WAXD results revealed that the fraction and orientation of crystals and the mesophase had slight changes in the elastic deformation zone of the fiber. However, in the plastic deformation zone of the fiber with a strain from 5 to 18%, the fraction of crystals gradually increased while the fraction of the mesophase decreased. During this deformation, the orientation of crystals (fc) firstly increased significantly and then increased slightly, while the orientation of the mesophase (fm) increased steadily beyond the yield point. When the strain exceeded 18%, the fraction of crystals decreased while the fraction of mesophase increased. The fc had a rapid increase again at a strain above 18%. A model was proposed to explain how the tensile deformation affects the molecular orientation of the hybrid fibers.
Co-reporter:Jian Chen;Ao Zhuang;Huili Shao;Xuechao Hu
Journal of Materials Chemistry B 2017 vol. 5(Issue 20) pp:3640-3650
Publication Date(Web):2017/05/24
DOI:10.1039/C7TB00485K
A big challenge in bone regeneration is preparation of an appropriate bone extracellular matrix that mimics the robust mechanical properties of the lamellar structure of natural bones as well as the in vivo micro-environment of bone cells. In this work, silk fibroin (SF)/bacterial cellulose nanoribbon (BCNR) composite scaffolds were prepared using various BCNR contents via a multi-staged freeze-drying method. The scaffolds showed a radial lamellar pattern and gradient lamellae gap distance, the structure of which could transfer nutrient solution and metabolic waste through a capillary effect, and can guide cells from the outer to the inner area of the scaffolds. The gap distance and thickness of the lamellae increased with increasing BCNRs contents. Parts of BCNRs attached to the surfaces of lamellae while others penetrated into it. The intercalation structure led to an eight-fold enhancement in compression modulus and six-fold increase in compression strength. These robust three-dimensional composite scaffolds with improved in vitro bioactivity, bone-cell adhesion, and proliferation are highly promising for further applications in bone defect repairs.
Co-reporter:Chao Zhang, Yaopeng Zhang, Huili Shao, and Xuechao Hu
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 5) pp:3349
Publication Date(Web):January 19, 2016
DOI:10.1021/acsami.5b11245
Regenerated silk fibroin (RSF)/graphene oxide (GO) hybrid silk fibers were dry-spun from a mixed dope of GO suspension and RSF aqueous solution. It was observed that the presence of GO greatly affect the viscosity of RSF solution. The RSF/GO hybrid fibers showed from FTIR result lower β-sheet content compared to that of pure RSF fibers. The result of synchrotron radiation wide-angle X-ray diffraction showed that the addition of GO confined the crystallization of silk fibroin (SF) leading to the decrease of crystallinity, smaller crystallite size, and new formation of interphase zones in the artificial silks. Synchrotron radiation small-angle X-ray scattering also proved that GO sheets in the hybrid silks and blended solutions were coated with a certain thickness of interphase zones due to the complex interaction between the two components. A low addition of GO, together with the mesophase zones formed between GO and RSF, enhanced the mechanical properties of hybrid fibers. The highest breaking stress of the hybrid fibers reached 435.5 ± 71.6 MPa, 23% improvement in comparison to that of degummed silk and 72% larger than that of pure RSF silk fiber. The hybrid RSF/GO materials with good biocompatibility and enhanced mechanical properties may have potential applications in tissue engineering, bioelectronic devices, or energy storage.Keywords: dry-spinning; graphene oxide; interphase; nanoconfined; regenerated silk fibroin; reinforced
Co-reporter:Jian-Wen Huang;Yue-Min Xu;Zhao-Bo Li;Sean V. Murphy;Weixin Zhao;Qiang-Qiang Liu;Wei-Dong Zhu;Qiang Fu;Yao-Peng Zhang;Lu-Jie Song
Journal of Biomedical Materials Research Part A 2016 Volume 104( Issue 1) pp:9-16
Publication Date(Web):
DOI:10.1002/jbm.a.35535
Abstract
The goal of this study was to investigate the tissue performance of bladder following stretched electrospun silk fibroin matrix (SESFM) implantation compared with bladder acellular matrix (BAM). We compared SESFM with BAM based on porosity and pore size. Scaffolds were separately transplanted into opposite walls of the bladder of 30 rabbits after stripping the bladder mucosa and smooth muscle (1.5 × 2.0 cm2). Gross anatomical observation, histological analysis and muscle contractility studies were performed at 2, 4, and 8 weeks post-op. SESFM has higher porosity and larger pore size compared with BAM (p < 0.05). At 2 weeks, the presence of vesical calculus was evident in 7/10 rabbits. Histological analysis showed that SESFM and BAM promoted similar degree of urothelium regeneration (p > 0.05). However, SESFM promoted a higher degree of smooth muscle and vessel regeneration compared to BAM (p < 0.05). In addition, muscle strips supported by SESFM displayed higher contractile responses to carbachol, KCl, and phenylephrine compared with BAM. At 8 weeks, both matrices elicited similar mild acute and chronic inflammatory reactions. Our results demonstrated that SESFM has greater ability to promote bladder tissue regeneration with structural and functional properties compared to BAM, and with similar biocompatibility. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 9–16, 2016.
Co-reporter:Qiangqiang Liu, Jianwen Huang, Huili Shao, Lujie Song and Yaopeng Zhang
RSC Advances 2016 vol. 6(Issue 9) pp:7683-7691
Publication Date(Web):11 Jan 2016
DOI:10.1039/C5RA22054H
To improve the therapeutic effect of a damaged peripheral nerve, aligned scaffolds based on regenerated silk fibroin (RSF) were fabricated by electrospinning, and were simultaneously loaded with dual factors of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). An ELISA assay measurement in vitro demonstrated that the release of dual factors from the scaffolds was well maintained up to 2 weeks. Schwann cell (SC) morphologies on the RSF scaffolds were obtained using scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM) after cell seeding. Cell viability and proliferation on the scaffolds were investigated using an MTT assay. Furthermore, the scaffolds were implanted in a mouse model to support nerve regeneration and angiogenesis in vivo, which was evaluated by histological and immunohistochemical (IHC) analyses at 4 and 8 weeks after implantation. In all retrieved scaffolds, de novo innervation and vascularization, indicated by a positive endothelial marker (von Willebrand factor, vWF) and an innervation marker (S-100 protein), were evident without chronic inflammatory responses. Compared to the control group, the dual-factor loaded scaffolds significantly promoted nerve regeneration and possessed great potential in peripheral nerve repair and regeneration, and for the repair of other tissues.
Co-reporter:Yaopeng Zhang, Jianwen Huang, Li Huang, Qiangqiang Liu, Huili Shao, Xuechao Hu, and Lujie Song
ACS Biomaterials Science & Engineering 2016 Volume 2(Issue 11) pp:2018
Publication Date(Web):September 6, 2016
DOI:10.1021/acsbiomaterials.6b00436
To investigate the synergistic effect of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) on cavernous nerve regeneration, two different aligned scaffolds consisting of coaxial electrospun silk fibers were prepared by switching the position of the two factors in either core or shell domain. The order and release rate of the dual factors delivery were relatively different because of the distinct location of two factors in coaxial fibers. An in vitro assay showed that the inner-VEGF/outer-BDNF scaffolds could more obviously accelerate Schwann cells growth, proliferation and spreading owing to the rapid release of BDNF. However, in vivo scaffold implantation demonstrated that the inner-BDNF/outer-VEGF scaffolds significantly facilitated more angiogenesis, and promoted more nerve regeneration based on great benefit of angiogenesis. Results showed that the reasonable dual-delivery order of VEGF and BDNF from scaffolds could enhance synergistic effect of the factors and promote cavernous nerve regeneration.Keywords: cavernous nerve regeneration; coaxial electrospinning; dual-delivery order; silk fibroin scaffolds
Co-reporter:Yatao Liu, Lixin Yin, Huirong Zhao, Guangkun Song, Fangming Tang, Lili Wang, Huili Shao, Yaopeng Zhang
Polymer 2016 Volume 105() pp:157-166
Publication Date(Web):22 November 2016
DOI:10.1016/j.polymer.2016.10.031
•Synchrotron radiation SAXS was mainly performed on two types of PET industrial fiber.•The evolution in lamellar and fibrillar structures of PET fibers in thermal annealing is presented.•Structure-property-process relationship of PET fibers is investigated.•Annealing significantly improves the structures of PET fiber with small and defective crystals.The evolutions in lamellar and fibrillar structures of poly(ethylene terephthalate) (PET) industrial fiber during taut-ends thermal annealing were investigated mainly using synchrotron radiation small-angle X-ray scattering (SAXS). Wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) results indicated that high modulus and low shrinkage PET fiber (HMLS) had high crystallinity and perfect crystals, whereas high modulus and low elongation fiber (HMLE) possessed relatively low crystallinity and defective crystals. As annealing temperature raised, the original four-spot SAXS pattern gradually turned into the coexistence of two- and four-spot pattern, together with the enhanced scattering intensity. The analysis of the lamellar peaks showed that the annealing process had a significant influence on the thickness of crystalline and amorphous region, as well as the long period at 125, 200 and 240 °C. At the same time, the lateral size of the lamellae raised, whereas the lamellar surface inclination declined. In addition, the streak scattering across the beam stop was attributed to the fibrils. Results suggested that fibrils subjected to thermal effect tended to grow in longitudinal direction and became more oriented along the fiber axis. This study might help to predict structure and property changes at high temperatures for PET fiber and any other well oriented fiber that has a lamellar and fibrillar structure.
Co-reporter:Lingyue Cai, Huili Shao, Xuechao Hu, and Yaopeng Zhang
ACS Sustainable Chemistry & Engineering 2015 Volume 3(Issue 10) pp:2551
Publication Date(Web):September 7, 2015
DOI:10.1021/acssuschemeng.5b00749
As the perfect combination of strength and luster, silkworm silks have been widely used in many fields but still need improvements. This paper demonstrates an in vivo uptake of titanium dioxide (TiO2) nanoparticles by silkworms, leading to the direct production of intrinsically modified silk. The nanoparticles can be easily incorporated into the silk gland of silkworm by using this method due to the interactions between TiO2 and silk fibroin molecules. Infrared spectra indicate that TiO2 nanoparticles confine the conformation transition of silk fibroin from random coil/α-helix to β-sheet. Results of synchrotron radiation wide-angle X-ray diffraction and small-angle X-ray scattering suggest that modified silks have lower crystallinity, higher mesophase content, and higher Herman’s orientation functions of crystalline region and mesophase region than control group. The breaking strength and elongation at break of the modified silk can be improved up to 548 ± 33 MPa and 16.7 ± 0.8%, respectively, by adding 1% nanoanatase into the artificial diet. Moreover, the TiO2-1% modified silk shows well-improved ultraviolet resistant property as the breaking strength only decreased 15.9% after exposure to ultraviolet light for 3 h. The in vivo modification method for silkworm silk is a green, sustainable, and promising route for commercial production in the future.Keywords: Artificial diet; Feeding method; Modification; Silkworm silk; TiO2;
Co-reporter:Zhaobo Li, Lujie Song, Xiangyu Huang, Hongsheng Wang, Huili Shao, Minkai Xie, Yuemin Xu and Yaopeng Zhang
RSC Advances 2015 vol. 5(Issue 22) pp:16748-16758
Publication Date(Web):29 Jan 2015
DOI:10.1039/C4RA16146G
Regenerated silk fibroin (RSF) scaffolds electrospun from aqueous solutions have great potential for tissue engineering. However, the traditional RSF mats are weak and limit the applications. A bladder acellular matrix graft (BAMG), a tough natural material, was used as an electrospinning substrate to toughen the RSF scaffolds. Compared with bare RSF scaffolds, the composite scaffolds with breaking energies ranging from 458 to 970 J kg−1 show significantly improved tensile properties and suture retention strength, which may satisfy the requirements for implantation. Vascular endothelial growth factor (VEGF) was encapsulated in the RSF/BAMG composite scaffolds by means of blend and coaxially electrospinning to promote the ability of vasculogenesis and angiogenesis. Transmission electron microscope (TEM) images show that the coaxially electrospun fibers had a core–sheath structure. An ELISA assay measurement indicates that VEGF can be released for more than 16 days. The samples annealed in water vapor exhibit higher release profiles than those immersed in ethanol. An in vitro assay indicates that VEGF loaded scaffolds evidently induced the attachment and proliferation of porcine iliac endothelial cells (PIECs) compared with those without VEGF. Moreover, the VEGF remained bioactive for up to 7 days. Thus the VEGF loaded composite scaffolds could be a promising candidate for tissue engineering applications.
Co-reporter:Yatao Liu;Lixin Yin;Huirong Zhao;Guangkun Song;Fangming Tang;Lili Wang;Huili Shao
Journal of Applied Polymer Science 2015 Volume 132( Issue 36) pp:
Publication Date(Web):
DOI:10.1002/app.42512
ABSTRACT
Synchrotron radiation wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) were performed to study the structures of four typical types of poly(ethylene terephthalate) (PET) industrial yarns. Three-dimensional structural models of the yarns and comprehensive insights into the process–structure–property relationships were gained. High spinning speed, low draw ratio, and high heat-setting temperatures lead to HMLS yarns with high crystallinity, high amorphous orientation, densely packed lamellar stacks, and a small tilting angle of crystalline lamellae. High draw ratio tends to result in PET industrial yarns with large long period and a large tilting angle of lamellae. Heat-setting process has a significant influence on the amorphous orientation and crystalline structures, such as crystallinity, crystallite size, as well as crystal grain number. Compared with other structure characteristics, amorphous orientation plays a more important role in determining the tenacity, initial modulus, part load elongation, ultimate elongation, as well as shrinkage of PET industrial yarns. The crystal grain number seems to have an effect on the initial modulus, while the long period influences the elongation of the yarns to some extent. In addition, the small tilting angle of crystalline lamellae may relate to the dimensional stability of PET yarns. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42512.
Co-reporter:Zhaobo Li, Qiangqiang Liu, Hongsheng Wang, Lujie Song, Huili Shao, Minkai Xie, Yuemin Xu, and Yaopeng Zhang
ACS Biomaterials Science & Engineering 2015 Volume 1(Issue 4) pp:238
Publication Date(Web):March 10, 2015
DOI:10.1021/ab5001436
Bombyx mori silk is of great interest to people for its outstanding mechanical and biological properties. However, the traditional electrospun regenerated silk fibroin (RSF) scaffolds from aqueous solution were weak and had limited applications. This study was to fabricate reinforced scaffolds with well-aligned RSF fibers electrospun on a layer of native extracellular matrix, bladder acellular matrix graft (BAMG). The silk fibroin fibers were well-aligned as a grill in multiple layers. Both the BAMG and the grill structure significantly improved the tensile properties and suture retention of the composite scaffolds, which can be sutured well with tissue during implantation. In vitro assay indicates that the scaffolds had a good biocompatibility. Porcine iliac endothelial cells (PIECs) attached and proliferated well on the vascular endothelial growth factor (VEGF) loaded scaffolds compared with those without VEGF. Moreover, the grill-like structure guides PIECs well along the aligned fiber.Keywords: BAMG; electrospinning; PIECs; VEGF; well-aligned RSF fibers
Co-reporter:Qingfa Peng, Huili Shao, Xuechao Hu, Yaopeng Zhang
Progress in Natural Science: Materials International 2015 Volume 25(Issue 5) pp:430-436
Publication Date(Web):October 2015
DOI:10.1016/j.pnsc.2015.09.006
Silk fiber was processed from highly concentrated spinning dope to solid fibers along with water removal. To understand the mechanism of water removal during silk fiber spinning process, a microfluidic chip was designed and applied to investigate the structures and mechanical properties of two kinds of regenerated silk fibroin fibers dry-spun at different relative humidity. The experimental results showed that the diameters of the fibers spun at 40% RH are always larger than the fibers spun at 50% RH due to different removal rates of water. The fibers spun at low humidity contain more β-sheet structure and lower degree of chain orientation and crystalline orientation. These results indicate that the fast phase transition of silk fibroin from sol–gel to silk fiber undergoes with rapid water removal and higher fiber orientation relates to more residue water and drawing force.
Co-reporter:Hui Pan, Yaopeng Zhang, Huili Shao, Xuechao Hu, Xiuhong Li, Feng Tian and Jie Wang
Journal of Materials Chemistry A 2014 vol. 2(Issue 10) pp:1408-1414
Publication Date(Web):06 Dec 2013
DOI:10.1039/C3TB21148G
Spider dragline silk is of great interest to people for its outstanding mechanical properties including high toughness. Biomimetic spinning of spider silk has attracted people's attention for decades. This paper reports a simple and cheap method to greatly toughen artificial silk by compositing with nanoanatase. The toughness of the artificial silk (breaking energy 93.1 ± 27.1 MJ m−3) exceeded that of silkworm silks. The hydrophilic nanomineral TiO2 with large specific surface area interacted severely with the fibroin matrix through coordination complexes (Ti–protein) and hydrogen bonds (O–H). Due to the interfacial interactions, regenerated silk fibroin (RSF)–TiO2 fibers showed higher α-helix/random coil content, lower β-sheet content, smaller crystallites and lower crystallinity than pure RSF fibers. A nanoconfined crystallite toughening mechanism was proposed to discuss the structure–property relationship of the hybrid fibers.
Co-reporter:Nannan Jiang, Xiangyu Huang, Zhaobo Li, Lujie Song, Hongsheng Wang, Yuemin Xu, Huili Shao and Yaopeng Zhang
RSC Advances 2014 vol. 4(Issue 88) pp:47570-47575
Publication Date(Web):10 Sep 2014
DOI:10.1039/C4RA05918B
Silk-based materials have great potentials in medical applications because of the proper mechanical properties and outstanding biocompatibility. This paper reports a novel method to prepare multi-layered silk fibroin (SF) tissue engineering scaffolds with well-aligned fibers oriented in different angles by an electrospinning process. The resulted aligned fibers construct the scaffolds with a grill-like structure, large area and improved mechanical properties, which have been demonstrated by scanning electron microscopy and tensile test. Biocompatibility analysis proves that the grill-like structure well guides the adhesion, proliferation and differentiation of porcine iliac endothelial cells along the aligned SF fibers in different directions.
Co-reporter:Mengjie Sun, Yaopeng Zhang, Yingmei Zhao, Huili Shao and Xuechao Hu
Journal of Materials Chemistry A 2012 vol. 22(Issue 35) pp:18372-18379
Publication Date(Web):03 Aug 2012
DOI:10.1039/C2JM32576D
Regenerated silk fibroin (RSF) fibers were dry-spun from RSF aqueous solution and then post-treated in ethanol aqueous solution. In order to prepare artificial silk which are tougher and stronger than their natural counterpart, the structure–property relationships of the RSF fibers and natural silkworm silks were investigated by using synchrotron radiation X-ray microdiffraction technology, birefringence measurements and Raman spectroscopy. The as-spun RSF fibers with poor mechanical properties exhibited a strong diffraction peak of the [021] lattice plane and a weak diffraction peak of the [020]/[200] lattice plane. However, both the natural silk and the post-treated RSF fibers with exceptional mechanical properties showed weak diffraction peaks of the [021] lattice plane and strong diffraction peaks of the [020]/[200] lattice plane. Nevertheless, the two crystalline peaks are attributed to the silk II structure of silk fibroin. By deconvoluting the one-dimensional wide-angle X-ray microdiffraction pattern, the crystallinity and the degree of crystalline orientation were obtained. The as-spun fibers showed low crystallinity and low crystalline orientation, but the microstructure of the RSF fibers could be improved greatly and even become similar to that of degummed cocoon silk by post-treatment. When the as-spun RSF fibers were first drawn 3 to 4 times with a draw rate of 0.9 mm s−1 in ethanol aqueous solution and then immersed in the same solution for another hour, the breaking strain and breaking energy of the post-treated fibers were significantly greater than those of degummed cocoon silk.
Co-reporter:Hui Pan, Yaopeng Zhang, Yichun Hang, Huili Shao, Xuechao Hu, Yuemin Xu, and Chao Feng
Biomacromolecules 2012 Volume 13(Issue 9) pp:
Publication Date(Web):August 10, 2012
DOI:10.1021/bm300877d
Microcomposite fibers of regenerated silk fibroin (RSF) and multiwalled carbon nanotubes (MWNTs) were successfully prepared by an electrospinning process from aqueous solutions. A quiescent blended solution and a three-dimensional Raman image of the composite fibers showed that functionalized MWNTs (F-MWNTs) were well dispersed in the solutions and the RSF fibers, respectively. Raman spectra and wide-angle X-ray diffraction (WAXD) patterns of RSF/F-MWNT electrospun fibers indicated that the composite fibers had higher β-sheet content and crystallinity than the pure RSF electrospun fibers, respectively. The mechanical properties of the RSF electrospun fibers were improved drastically by incorporating F-MWNTs. Compared with the pure RSF electrospun fibers, the composite fibers with 1.0 wt % F-MWNTs exhibited a 2.8-fold increase in breaking strength, a 4.4-fold increase in Young’s modulus, and a 2.1-fold increase in breaking energy. Cytotoxicity test preliminarily demonstrated that the electrospun fiber mats have good biocompatibility for tissue engineering scaffolds.
Co-reporter:Jie Luo, Yaopeng Zhang, Yan Huang, Huili Shao, Xuechao Hu
Sensors and Actuators B: Chemical 2012 Volume 162(Issue 1) pp:435-440
Publication Date(Web):20 February 2012
DOI:10.1016/j.snb.2011.12.093
In this article, microfluidic channels (500 μm in width, 65–85 μm in depth) in micro-chips were fabricated in poly-(dimethylsiloxane) (PDMS) on a mold of SU-8 photoresist based on photolithography process. By biomimicking the silk glands and the spinning duct of silkworms, the chips were designed and used for the concentration of regenerated silk fibroin (RSF) aqueous solution. The microfluidic devices based on regenerated cellulose membrane involve a flow of RSF aqueous solution on a donor side and a flow of polyethyleneglycol (PEG) aqueous solution on an acceptor side. The enrichment factor was characterized by varying the flow rates of the RSF solution and the PEG solution, and the concentrations of PEG and RSF solutions at inlets. The results showed that the enrichment efficiency varied as the flow factors changed. The RSF concentration of the solution was enriched up to 31.2 wt% from 12 wt% by using the microfluidic chip. The experiments facilitated the enrichment of RSF solution in a microfluidic channel as silkworm did. It might be further applied for the microfluidic spinning of RSF fiber.
Co-reporter:Wei Wei, Yaopeng Zhang, Yingmei Zhao, Jie Luo, Huili Shao, Xuechao Hu
Materials Science and Engineering: C 2011 Volume 31(Issue 7) pp:1602-1608
Publication Date(Web):10 October 2011
DOI:10.1016/j.msec.2011.07.013
To biomimic the spinning process of silkworm or spider, a capillary spinning equipment was applied to spin regenerated silk fibroin (RSF) fibers from RSF aqueous solutions in air. This equipment exhibits a wide processing window for various RSF aqueous solutions. The effects of pH, metal ions, RSF concentration and spinning parameters on the spinnability of the spinning dope and the mechanical properties of the obtained fibers were investigated. As a result, spinning dopes with a pH from 5.2 to 6.9 have good spinnability, especially for the dope with a pH of 6.0 and a Ca2+ concentration of 0.3 M. The RSF concentration of this dope ranges from 44% to 48%. Under optimized conditions of our dry spinning experiments (L/D, 133; take-up speed, 30 mm/s), the obtained as-spun fiber has a breaking strength of 46 MPa, which can be improved up to 359 MPa after a preliminary post-drawing in 80 vol.% ethanol aqueous solution.Highlights► Regenerated silk fibroin fibers were prepared by using a dry spinning method. ► Dope compositions affect dope spinnability. ► Spinning parameters affect dope spinnability and fiber properties. ► The breaking stress of the post-treated fiber was up to 359 MPa.
Co-reporter:Mengjie Sun, Yaopeng Zhang, Yingmei Zhao, Huili Shao and Xuechao Hu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 35) pp:NaN18379-18379
Publication Date(Web):2012/08/03
DOI:10.1039/C2JM32576D
Regenerated silk fibroin (RSF) fibers were dry-spun from RSF aqueous solution and then post-treated in ethanol aqueous solution. In order to prepare artificial silk which are tougher and stronger than their natural counterpart, the structure–property relationships of the RSF fibers and natural silkworm silks were investigated by using synchrotron radiation X-ray microdiffraction technology, birefringence measurements and Raman spectroscopy. The as-spun RSF fibers with poor mechanical properties exhibited a strong diffraction peak of the [021] lattice plane and a weak diffraction peak of the [020]/[200] lattice plane. However, both the natural silk and the post-treated RSF fibers with exceptional mechanical properties showed weak diffraction peaks of the [021] lattice plane and strong diffraction peaks of the [020]/[200] lattice plane. Nevertheless, the two crystalline peaks are attributed to the silk II structure of silk fibroin. By deconvoluting the one-dimensional wide-angle X-ray microdiffraction pattern, the crystallinity and the degree of crystalline orientation were obtained. The as-spun fibers showed low crystallinity and low crystalline orientation, but the microstructure of the RSF fibers could be improved greatly and even become similar to that of degummed cocoon silk by post-treatment. When the as-spun RSF fibers were first drawn 3 to 4 times with a draw rate of 0.9 mm s−1 in ethanol aqueous solution and then immersed in the same solution for another hour, the breaking strain and breaking energy of the post-treated fibers were significantly greater than those of degummed cocoon silk.
Co-reporter:Hui Pan, Yaopeng Zhang, Huili Shao, Xuechao Hu, Xiuhong Li, Feng Tian and Jie Wang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 10) pp:NaN1414-1414
Publication Date(Web):2013/12/06
DOI:10.1039/C3TB21148G
Spider dragline silk is of great interest to people for its outstanding mechanical properties including high toughness. Biomimetic spinning of spider silk has attracted people's attention for decades. This paper reports a simple and cheap method to greatly toughen artificial silk by compositing with nanoanatase. The toughness of the artificial silk (breaking energy 93.1 ± 27.1 MJ m−3) exceeded that of silkworm silks. The hydrophilic nanomineral TiO2 with large specific surface area interacted severely with the fibroin matrix through coordination complexes (Ti–protein) and hydrogen bonds (O–H). Due to the interfacial interactions, regenerated silk fibroin (RSF)–TiO2 fibers showed higher α-helix/random coil content, lower β-sheet content, smaller crystallites and lower crystallinity than pure RSF fibers. A nanoconfined crystallite toughening mechanism was proposed to discuss the structure–property relationship of the hybrid fibers.
Co-reporter:Jian Chen, Ao Zhuang, Huili Shao, Xuechao Hu and Yaopeng Zhang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 20) pp:NaN3650-3650
Publication Date(Web):2017/04/20
DOI:10.1039/C7TB00485K
A big challenge in bone regeneration is preparation of an appropriate bone extracellular matrix that mimics the robust mechanical properties of the lamellar structure of natural bones as well as the in vivo micro-environment of bone cells. In this work, silk fibroin (SF)/bacterial cellulose nanoribbon (BCNR) composite scaffolds were prepared using various BCNR contents via a multi-staged freeze-drying method. The scaffolds showed a radial lamellar pattern and gradient lamellae gap distance, the structure of which could transfer nutrient solution and metabolic waste through a capillary effect, and can guide cells from the outer to the inner area of the scaffolds. The gap distance and thickness of the lamellae increased with increasing BCNRs contents. Parts of BCNRs attached to the surfaces of lamellae while others penetrated into it. The intercalation structure led to an eight-fold enhancement in compression modulus and six-fold increase in compression strength. These robust three-dimensional composite scaffolds with improved in vitro bioactivity, bone-cell adhesion, and proliferation are highly promising for further applications in bone defect repairs.
