1
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Wöltje M, Kölbel A, Aibibu D, Cherif C. A Fast and Reliable Process to Fabricate Regenerated Silk Fibroin Solution from Degummed Silk in 4 Hours. Int J Mol Sci 2021; 22:ijms221910565. [PMID: 34638905 PMCID: PMC8508919 DOI: 10.3390/ijms221910565] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 09/27/2021] [Accepted: 09/27/2021] [Indexed: 11/23/2022] Open
Abstract
Silk fibroin has a high potential for use in several approaches for technological and biomedical applications. However, industrial production has been difficult to date due to the lengthy manufacturing process. Thus, this work investigates a novel procedure for the isolation of non-degraded regenerated silk fibroin that significantly reduces the processing time from 52 h for the standard methods to only 4 h. The replacement of the standard degumming protocol by repeated short-term microwave treatments enabled the generation of non-degraded degummed silk fibroin. Subsequently, a ZnCl2 solution was used to completely solubilize the degummed fibroin at only 45 °C with an incubation time of only 1 h. Desalting was performed by gel filtration. Based on these modifications, it was possible to generate a cytocompatible aqueous silk fibroin solution from degummed silk within only 4 h, thus shortening the total process time by 48 h without degrading the quality of the isolated silk fibroin solution.
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2
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Pan L, Wang F, Cheng Y, Leow WR, Zhang YW, Wang M, Cai P, Ji B, Li D, Chen X. A supertough electro-tendon based on spider silk composites. Nat Commun 2020; 11:1332. [PMID: 32165612 PMCID: PMC7067870 DOI: 10.1038/s41467-020-14988-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 02/11/2020] [Indexed: 11/10/2022] Open
Abstract
Compared to transmission systems based on shafts and gears, tendon-driven systems offer a simpler and more dexterous way to transmit actuation force in robotic hands. However, current tendon fibers have low toughness and suffer from large friction, limiting the further development of tendon-driven robotic hands. Here, we report a super tough electro-tendon based on spider silk which has a toughness of 420 MJ/m3 and conductivity of 1,077 S/cm. The electro-tendon, mechanically toughened by single-wall carbon nanotubes (SWCNTs) and electrically enhanced by PEDOT:PSS, can withstand more than 40,000 bending-stretching cycles without changes in conductivity. Because the electro-tendon can simultaneously transmit signals and force from the sensing and actuating systems, we use it to replace the single functional tendon in humanoid robotic hand to perform grasping functions without additional wiring and circuit components. This material is expected to pave the way for the development of robots and various applications in advanced manufacturing and engineering.
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Affiliation(s)
- Liang Pan
- Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Fan Wang
- Biomechanics and Biomaterials Laboratory, Department of Applied Mechanics, Beijing Institute of Technology, Beijing, 100081, China
| | - Yuan Cheng
- Institute of High Performance Computing, Agency for Science Technology and Research (A*STAR), 1 Fusionopolis Way, Singapore, 138632, Singapore
| | - Wan Ru Leow
- Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Yong-Wei Zhang
- Institute of High Performance Computing, Agency for Science Technology and Research (A*STAR), 1 Fusionopolis Way, Singapore, 138632, Singapore
| | - Ming Wang
- Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Pingqiang Cai
- Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Baohua Ji
- Institute of Applied Mechanics, Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310027, China
| | - Dechang Li
- Institute of Applied Mechanics, Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310027, China.
| | - Xiaodong Chen
- Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
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3
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Abstract
Feeding Bombyx mori larvae with chemically-modified diets affects the structure and properties of the resulted silk. Herein, we provide a road map for the use of silkworms as a factory to produce semiconducting/metallic natural silk that can be used in many technological applications such as supercapacitor electrodes. The silkworms were fed with four different types of chemicals; carbon material (graphite), sulfide (MoS2), oxide (TiO2 nanotubes), and a mixture of reactive chemicals (KMnO4/MnCl2). All the fed materials were successfully integrated into the resulted silk. The capacitive performance of the resulted silk was evaluated as self-standing fabric electrodes as well as on glassy carbon substrates. The self-standing silk and the silk@glassy carbon substrate showed a great enhancement in the capacitive performance over that of the unmodified counterparts. The specific capacitance of the self-standing blank silk negative and positive electrodes was enhanced 4 and 5 folds at 10 mV/s, respectively upon the modification with KMnO4/MnCl2 compared to that of the plain silk electrodes.
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Affiliation(s)
- Basant A Ali
- Energy Materials Laboratory (EML), School of Sciences and Engineering, The American University in Cairo, New Cairo, 11835, Egypt
| | - Nageh K Allam
- Energy Materials Laboratory (EML), School of Sciences and Engineering, The American University in Cairo, New Cairo, 11835, Egypt.
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4
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Li G, Qin S, Zhang D, Liu X. Preparation of antibacterial degummed silk fiber/nano-hydroxyapatite/polylactic acid composite scaffold by degummed silk fiber loaded silver nanoparticles. Nanotechnology 2019; 30:295101. [PMID: 30917342 DOI: 10.1088/1361-6528/ab13df] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this study, an antibacterial degummed silk fiber (ADSF)/nano-hydroxyapatite/polylactic acid (ADSF/nHA/PLA) porous scaffold with antibacterial properties was prepared by using degummed silk fiber (DSF) loaded with silver nano-particles (Ag NPs) as a reinforcing material. In the experiment, ADSF and nHA were used as the main variables to investigate the effect of the change of the composition ratio on the performance of the composite scaffold, and a composite scaffold with excellent performance was obtained. Firstly, the DSFs were treated with dopamine (DA) and the silver ions were reduced to Ag NPs using the strong reducibility of polydopamine (PDA) to prepare ADSF loaded with Ag NPs. Finally, ADSF/nHA/PLA composite scaffolds with antibacterial properties were prepared using ADSF as a reinforcing material. In addition, samples were found to have good mineralization capacity in in vitro mineralization experiments. At the same time, in cell culture and antibacterial experiments, ADSF/nHA/PLA scaffolds were found to have good bioactivity, biocompatibility and antibacterial properties. All the results showed that the Ag NPs loaded DSF improved the performance of the nHA/PLA composite scaffold, while the ADSF/nHA/PLA had good bioactivity and antibacterial properties, making the antibacterial ADSF/nHA/PLA composite scaffold has a great potential for bone tissue engineering.
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Affiliation(s)
- Gang Li
- College of Materials Science and Metallurgy Engineering, Guizhou University, Guiyang 550025, People's Republic of China. National Engineering Research Center for Compounding and Modification of Polymeric Materials, Guiyang 550014, People's Republic of China
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5
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Gu J, Li Q, Chen B, Xu C, Zheng H, Zhou Y, Peng Z, Hu Z, Wang B. Species identification of Bombyx mori and Antheraea pernyi silk via immunology and proteomics. Sci Rep 2019; 9:9381. [PMID: 31253818 PMCID: PMC6599025 DOI: 10.1038/s41598-019-45698-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 05/29/2019] [Indexed: 11/20/2022] Open
Abstract
In recent years, increasing attention has been paid to the origin, transmission and communication of silk. However, this is still an unsolved mystery in archaeology. The identification of silk-producing species, especially silk produced by Bombyx mori (B. mori) and Antheraea pernyi (A. pernyi), is of key significance to address this challenge. In this study, two innovative methods, i.e. immunology and proteomics, were proposed and successfully established for the species identification of silks. ELISAs result demonstrated that the two prepared antibodies exhibited high sensitivity and specificity in distinguishing B. mori and A. pernyi silk. No cross-reactivity with each other was observed. Moreover, biomarkers were obtained for Bombyx and Antheraea through proteomic analysis. It was also confirmed that the biomarkers were suitable for identifying the species that produced a given silk sample. Compared with conventional methods for distinguishing silk species, immunological and proteomics techniques used in tandem can provide intact information and have the potential to provide accurate and reliable information for species identification.
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Affiliation(s)
- Jincui Gu
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Qingqing Li
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Boyi Chen
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Chengfeng Xu
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Hailing Zheng
- Key Scientific Research Base of Textile Conservation, State Administration for Cultural Heritage, China National Silk Museum, Hangzhou, 310002, China
| | - Yang Zhou
- Key Scientific Research Base of Textile Conservation, State Administration for Cultural Heritage, China National Silk Museum, Hangzhou, 310002, China.
| | - Zhiqin Peng
- Institute of Textile Conservation, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Zhiwen Hu
- Institute of Textile Conservation, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Bing Wang
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
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6
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Greco G, Pantano MF, Mazzolai B, Pugno NM. Imaging and mechanical characterization of different junctions in spider orb webs. Sci Rep 2019; 9:5776. [PMID: 30962468 PMCID: PMC6453893 DOI: 10.1038/s41598-019-42070-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 03/05/2019] [Indexed: 11/20/2022] Open
Abstract
Spider silk and spider orb webs are among the most studied biological materials and structures owing to their outstanding mechanical properties. A key feature that contributes significantly to the robustness and capability to absorb high kinetic energy of spider webs is the presence of junctions connecting different silk threads. Surprisingly, in spite of their fundamental function, the mechanics of spider web junctions have never been reported. Herein, through mechanical characterization and imaging, we show for the first time that spider orb webs host two different types of junction, produced by different silk glands, which have different morphology, and load bearing capability. These differences can be explained in view of the different roles they play in the web, i.e. allowing for a localized damage control or anchoring the whole structure to the surrounding environment.
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Affiliation(s)
- Gabriele Greco
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, 38123, Trento, Italy
- Center for Micro-BioRobotics@SSSA, Istituto Italiano di Tecnologia, Viale Rinaldo Piaggio 34, I-56025, Pontedera, Italy
| | - Maria F Pantano
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, 38123, Trento, Italy
| | - Barbara Mazzolai
- Center for Micro-BioRobotics@SSSA, Istituto Italiano di Tecnologia, Viale Rinaldo Piaggio 34, I-56025, Pontedera, Italy
| | - Nicola M Pugno
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, 38123, Trento, Italy.
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1 4NS, London, United Kingdom.
- Ket-Lab, Edoardo Amaldi Foundation, Via del Politecnico snc, 00133, Rome, Italy.
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7
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Yoshioka T, Tsubota T, Tashiro K, Jouraku A, Kameda T. A study of the extraordinarily strong and tough silk produced by bagworms. Nat Commun 2019; 10:1469. [PMID: 30931923 PMCID: PMC6443776 DOI: 10.1038/s41467-019-09350-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/27/2019] [Indexed: 01/03/2023] Open
Abstract
Global ecological damage has heightened the demand for silk as 'a structural material made from sustainable resources'. Scientists have earnestly searched for stronger and tougher silks. Bagworm silk might be a promising candidate considering its superior capacity to dangle a heavy weight, summed up by the weights of the larva and its house. However, detailed mechanical and structural studies on bagworm silks have been lacking. Herein, we show the superior potential of the silk produced by Japan's largest bagworm, Eumeta variegata. This bagworm silk is extraordinarily strong and tough, and its tensile deformation behaviour is quite elastic. The outstanding mechanical property is the result of a highly ordered hierarchical structure, which remains unchanged until fracture. Our findings demonstrate how the hierarchical structure of silk proteins plays an important role in the mechanical property of silk fibres.
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Affiliation(s)
- Taiyo Yoshioka
- Silk Materials Research Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Takuya Tsubota
- Transgenic Silkworm Research Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Kohji Tashiro
- Department of Future Industry-Oriented Basic Science and Materials, Graduate School of Engineering, Toyota Technological Institute, Tempaku, Nagoya, 468-8511, Japan
| | - Akiya Jouraku
- Insect Genome Research and Engineering Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Tsunenori Kameda
- Silk Materials Research Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan.
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8
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Xu L, Weatherbee-Martin N, Liu XQ, Rainey JK. Recombinant Silk Fiber Properties Correlate to Prefibrillar Self-Assembly. Small 2019; 15:e1805294. [PMID: 30756524 DOI: 10.1002/smll.201805294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/18/2019] [Indexed: 06/09/2023]
Abstract
Spider silks are desirable materials with mechanical properties superior to most synthetic materials coupled with biodegradability and biocompatibility. In order to replicate natural silk properties using recombinant spider silk proteins (spidroins) and wet-spinning methods, the focus to date has typically been on modifying protein sequence, protein size, and spinning conditions. Here, an alternative approach is demonstrated. Namely, using the same ≈57 kDa recombinant aciniform silk protein with a consistent wet-spinning protocol, fiber mechanical properties are shown to significantly differ as a function of the solvent used to dissolve the protein at high concentration (the "spinning dope" solution). A fluorinated acid/alcohol/water dope leads to drastic improvement in fibrillar extensibility and, correspondingly, toughness compared to fibers produced using a previously developed fluorinated alcohol/water dope. To understand the underlying cause for these mechanical differences, morphology and structure of the two classes of silk fiber are compared, with features tracing back to dope-state protein structuring and preassembly. Specifically, distinct classes of spidroin nanoparticles appear to form in each dope prior to fiber spinning and these preassembled states are, in turn, linked to fiber morphology, structure, and mechanical properties. Tailoring of dope-state spidroin nanoparticle assembly, thus, appears a promising strategy to modulate fibrillar silk properties.
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Affiliation(s)
- Lingling Xu
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Nathan Weatherbee-Martin
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Xiang-Qin Liu
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Jan K Rainey
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
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9
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Babczyńska A, Sułowicz S, Talik E, Hermyt M, Bednarek A, Sawadro M, Molenda A. Sterile Capsule-Egg Cocoon Covering Constitutes an Antibacterial Barrier for Spider Parasteatoda tepidariorum Embryos. Physiol Biochem Zool 2019; 92:115-124. [PMID: 30601104 DOI: 10.1086/701390] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Coexistence of organisms and pathogens has resulted in the evolution of efficient antimicrobial defense, especially at the embryonic stage. This investigation aimed to substantiate the hypothesis that the layers of silk in a spider cocoon play a role in the immunity of the embryos against microorganisms present in the external environment. A two-step interdisciplinary attempt has been made. First, the eggs and empty cocoons of the spider Parasteatoda tepidariorum were incubated on lysogeny broth agar media for 3 d. In the samples of eggs, no growth of bacteria was detected. This indicated that the eggs inside cocoons were sterile. Therefore, in the second step, the cocoons and egg surface were analyzed using SEM, TEM, and LM. The obtained images demonstrated that both inner and outer layers of the silk are built of threads of the same diameter, set in an irregular manner, and randomly clustered into groups. The threads in the outer layer were packed more densely than in the inner one. TEM analysis revealed threads of two types of fibrils and their arrangement. The resultant thread tangle of the cocoon, possibly correlated with the ultrastructure of the fibers, seems to be an example of a structure-function relationship playing a crucial ecoimmunological role in spider embryonic development.
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10
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You Z, Ye X, Ye L, Qian Q, Wu M, Song J, Che J, Zhong B. Extraordinary Mechanical Properties of Composite Silk Through Hereditable Transgenic Silkworm Expressing Recombinant Major Ampullate Spidroin. Sci Rep 2018; 8:15956. [PMID: 30374029 PMCID: PMC6206087 DOI: 10.1038/s41598-018-34150-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 07/02/2018] [Indexed: 12/30/2022] Open
Abstract
Spider dragline silk is a remarkable material that shows excellent mechanical properties, diverse applications, biocompatibility and biodegradability. Transgenic silkworm technology was used to obtain four types of chimeric silkworm/spider (termed composite) silk fibres, including different lengths of recombinant Major ampullate Spidroin1 (re-MaSp1) or recombinant Major ampullate Spidroin2 (re-MaSp2) from the black widow spider, Latrodectus hesperus. The results showed that the overall mechanical properties of composite silk fibres improved as the re-MaSp1 chain length increased, and there were significant linear relationships between the mechanical properties and the re-MaSp1 chain length (p < 0.01). Additionally, a stronger tensile strength was observed for the composite silk fibres that included re-MaSp1, which only contained one type of repetitive motif, (GA)n/An, to provide tensile strength, compared with the silk fibres that includedre-MaSp2, which has the same protein chain length as re-MaSp1 but contains multiple types of repetitive motifs, GPGXX and (GA)n/An. Therefore, the results indicated that the nature of various repetitive motifs in the primary structure played an important role in imparting excellent mechanical properties to the protein-based silk fibres. A silk protein with a single type of repetitive motif and sufficiently long chains was determined to be an additional indispensable factor. Thus, this study forms a foundation for designing and optimizing the structure of re-silk protein using a heterologous expression system.
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Affiliation(s)
- Zhengying You
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Xiaogang Ye
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Lupeng Ye
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Qiujie Qian
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Meiyu Wu
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Jia Song
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Jiaqian Che
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Boxiong Zhong
- College of Animal Science, Zhejiang University, Hangzhou, 310058, P. R. China.
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11
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Abstract
Silks are natural fibrous protein polymers that are spun by silkworms and spiders. Among silk variants, there has been increasing interest devoted to the silkworm silk of B. mori, due to its availability in large quantities along with its unique material properties. Silk fibroin can be extracted from the cocoons of the B. mori silkworm and combined synergistically with other biomaterials to form biopolymer composites. With the development of recombinant DNA technology, silks can also be rationally designed and synthesized via genetic control. Silk proteins can be processed in aqueous environments into various material formats including films, sponges, electrospun mats and hydrogels. The versatility and sustainability of silk-based materials provides an impressive toolbox for tailoring materials to meet specific applications via eco-friendly approaches. Historically, silkworm silk has been used by the textile industry for thousands of years due to its excellent physical properties, such as lightweight, high mechanical strength, flexibility, and luster. Recently, due to these properties, along with its biocompatibility, biodegradability and non-immunogenicity, silkworm silk has become a candidate for biomedical utility. Further, the FDA has approved silk medical devices for sutures and as a support structure during reconstructive surgery. With increasing needs for implantable and degradable devices, silkworm silk has attracted interest for electronics, photonics for implantable yet degradable medical devices, along with a broader range of utility in different device applications. This Tutorial review summarizes and highlights recent advances in the use of silk-based materials in bio-nanotechnology, with a focus on the fabrication and functionalization methods for in vitro and in vivo applications in the field of tissue engineering, degradable devices and controlled release systems.
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Affiliation(s)
- Wenwen Huang
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA.
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12
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Guo J, Li C, Ling S, Huang W, Chen Y, Kaplan DL. Multiscale design and synthesis of biomimetic gradient protein/biosilica composites for interfacial tissue engineering. Biomaterials 2017; 145:44-55. [PMID: 28843732 PMCID: PMC5610098 DOI: 10.1016/j.biomaterials.2017.08.025] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/16/2017] [Accepted: 08/14/2017] [Indexed: 01/13/2023]
Abstract
Continuous gradients present at tissue interfaces such as osteochondral systems, reflect complex tissue functions and involve changes in extracellular matrix compositions, cell types and mechanical properties. New and versatile biomaterial strategies are needed to create suitable biomimetic engineered grafts for interfacial tissue engineering. Silk protein-based composites, coupled with selective peptides with mineralization domains, were utilized to mimic the soft-to-hard transition in osteochondral interfaces. The gradient composites supported tunable mineralization and mechanical properties corresponding to the spatial concentration gradient of the mineralization domains (R5 peptide). The composite system exhibited continuous transitions in terms of composition, structure and mechanical properties, as well as cytocompatibility and biodegradability. The gradient silicified silk/R5 composites promoted and regulated osteogenic differentiation of human mesenchymal stem cells in an osteoinductive environment in vitro. The cells differentiated along the composites in a manner consistent with the R5-gradient profile. This novel biomimetic gradient biomaterial design offers a useful approach to meet a broad range of needs in regenerative medicine.
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Affiliation(s)
- Jin Guo
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA; Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Chunmei Li
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Shengjie Ling
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA; Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Wenwen Huang
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Ying Chen
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA.
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13
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Zhao B, Cohen Stuart MA, Hall CK. Navigating in foldonia: Using accelerated molecular dynamics to explore stability, unfolding and self-healing of the β-solenoid structure formed by a silk-like polypeptide. PLoS Comput Biol 2017; 13:e1005446. [PMID: 28329017 PMCID: PMC5388506 DOI: 10.1371/journal.pcbi.1005446] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 04/11/2017] [Accepted: 03/08/2017] [Indexed: 11/22/2022] Open
Abstract
The β roll molecules with sequence (GAGAGAGQ)10 stack via hydrogen bonding to form fibrils which have been themselves been used to make viral capsids of DNA strands, supramolecular nanotapes and pH-responsive gels. Accelerated molecular dynamics (aMD) simulations are used to investigate the unfolding of a stack of two β roll molecules, (GAGAGAGQ)10, to shed light on the folding mechanism by which silk-inspired polypeptides form fibrils and to identify the dominant forces that keep the silk-inspired polypeptide in a β roll configuration. Our study shows that a molecule in a stack of two β roll molecules unfolds in a step-wise fashion mainly from the C terminal. The bottom template is found to play an important role in stabilizing the β roll structure of the molecule on top by strengthening the hydrogen bonds in the layer that it contacts. Vertical hydrogen bonds within the β roll structure are considerably weaker than lateral hydrogen bonds, signifying the importance of lateral hydrogen bonds in stabilizing the β roll structure. Finally, an intermediate structure was found containing a β hairpin and an anti-parallel β sheet consisting of strands from the top and bottom molecules, revealing the self-healing ability of the β roll stack.
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Affiliation(s)
- Binwu Zhao
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States
| | - Martien A. Cohen Stuart
- Laboratory of Physical Chemistry & Colloid Science, Wageningen University, NL, Wageningen, The Netherlands
| | - Carol K. Hall
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States
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14
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Rodriguez MJ, Brown J, Giordano J, Lin SJ, Omenetto FG, Kaplan DL. Silk based bioinks for soft tissue reconstruction using 3-dimensional (3D) printing with in vitro and in vivo assessments. Biomaterials 2017; 117:105-115. [PMID: 27940389 PMCID: PMC5180454 DOI: 10.1016/j.biomaterials.2016.11.046] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Revised: 11/15/2016] [Accepted: 11/24/2016] [Indexed: 02/07/2023]
Abstract
In the field of soft tissue reconstruction, custom implants could address the need for materials that can fill complex geometries. Our aim was to develop a material system with optimal rheology for material extrusion, that can be processed in physiological and non-toxic conditions and provide structural support for soft tissue reconstruction. To meet this need we developed silk based bioinks using gelatin as a bulking agent and glycerol as a non-toxic additive to induce physical crosslinking. We developed these inks optimizing printing efficacy and resolution for patient-specific geometries that can be used for soft tissue reconstruction. We demonstrated in vitro that the material was stable under physiological conditions and could be tuned to match soft tissue mechanical properties. We demonstrated in vivo that the material was biocompatible and could be tuned to maintain shape and volume up to three months while promoting cellular infiltration and tissue integration.
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Affiliation(s)
- María J Rodriguez
- Department of Biomedical Engineering, Tufts University, Medford, MA, USA
| | - Joseph Brown
- Department of Biomedical Engineering, Tufts University, Medford, MA, USA
| | - Jodie Giordano
- Department of Biomedical Engineering, Tufts University, Medford, MA, USA
| | - Samuel J Lin
- Division of Plastic and Reconstructive Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | | | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA, USA.
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15
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Randrianandrasana M, Wu WY, Carney DA, Wagoner Johnson AJ, Berenbaum MR. Structural and Mechanical Properties of Cocoons of Antherina suraka (Saturniidae, Lepidoptera), an Endemic Species Used for Silk Production in Madagascar. J Insect Sci 2017; 17:iew112. [PMID: 28130459 PMCID: PMC5270396 DOI: 10.1093/jisesa/iew112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Indexed: 06/06/2023]
Abstract
Antherina suraka Boisduval (Saturniidae, Lepidoptera) produces a silken cocoon that has been the focus of efforts to create a commercial wild silk industry in Madagascar. In this study, structural and mechanical properties of the cocoon of A. suraka from two sites were measured and compared to the cocoon of Bombyx mori L. (Bombycidae, Lepidoptera) the world's most common source for silk. Results of environmental scanning electron microscopy and mechanical testing showed that the silk sheet of A. suraka cocoon is less compact, with greater thickness and lower tensile strength and stiffness than that of B. mori Confirming these results, stiffness and cell and thread density were found to be negatively correlated with thickness, and the cell and thread volumes were positively correlated with thickness. Antherina suraka showed no major differences between silk sheets from Kirindy and Isalo sites in either structural or mechanical properties, except for mean cell volume, which was greater in cocoons from Kirindy. Comparison between the two layers forming the cocoon showed that the inner layer has greater elastic modulus, denser silk distribution and lower porosity. Cocoons from both Kirindy and Isalo are suitable for sericulture. Although the inner layer of cocoon silk is of higher quality than the outer layer, the fact that both layers are of great but lower tensile strength than B. mori silk suggests that the current practice of sewing the two layers together for making one single layer fabric should be continued in efforts to produce a commercially viable product.
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Affiliation(s)
- Maminirina Randrianandrasana
- Department of Entomology, University of Illinois at Urbana-Champaign, 320 Morrill Hall, 505 S. Goodwin Ave, Urbana, IL 61801
| | - Wen-Yen Wu
- Department of Entomology, University of Illinois at Urbana-Champaign, 320 Morrill Hall, 505 S. Goodwin Ave, Urbana, IL 61801
| | - David A Carney
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801
| | - Amy J Wagoner Johnson
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801
| | - May R Berenbaum
- Department of Entomology, University of Illinois at Urbana-Champaign, 320 Morrill Hall, 505 S. Goodwin Ave, Urbana, IL 61801
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16
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Vu T, Xue Y, Vuong T, Erbe M, Bennet C, Palazzo B, Popielski L, Rodriguez N, Hu X. Comparative Study of Ultrasonication-Induced and Naturally Self-Assembled Silk Fibroin-Wool Keratin Hydrogel Biomaterials. Int J Mol Sci 2016; 17:E1497. [PMID: 27618011 PMCID: PMC5037774 DOI: 10.3390/ijms17091497] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 08/24/2016] [Accepted: 08/30/2016] [Indexed: 11/30/2022] Open
Abstract
This study reports the formation of biocompatible hydrogels using protein polymers from natural silk cocoon fibroins and sheep wool keratins. Silk fibroin protein contains β-sheet secondary structures, allowing for the formation of physical cross-linkers in the hydrogels. Comparative studies were performed on two groups of samples. In the first group, ultrasonication was used to induce a quick gelation of a protein aqueous solution, enhancing the ability of Bombyx mori silk fibroin chains to quickly entrap the wool keratin protein molecules homogenously. In the second group, silk/keratin mixtures were left at room temperature for days, resulting in naturally-assembled gelled solutions. It was found that silk/wool blended solutions can form hydrogels at different mixing ratios, with perfectly interconnected gel structure when the wool content was less than 30 weight percent (wt %) for the first group (ultrasonication), and 10 wt % for the second group (natural gel). Differential scanning calorimetry (DSC) and temperature modulated DSC (TMDSC) were used to confirm that the fibroin/keratin hydrogel system was well-blended without phase separation. Fourier transform infrared spectroscopy (FTIR) was used to investigate the secondary structures of blended protein gels. It was found that intermolecular β-sheet contents significantly increase as the system contains more silk for both groups of samples, resulting in stable crystalline cross-linkers in the blended hydrogel structures. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the samples' characteristic morphology on both micro- and nanoscales, which showed that ultrasonic waves can significantly enhance the cross-linker formation and avoid phase separation between silk and keratin molecules in the blended systems. With the ability to form cross-linkages non-chemically, these silk/wool hydrogels may be economically useful for various biomedical applications, thanks to the good biocompatibility of protein molecules and the various characteristics of hydrogel systems.
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Affiliation(s)
- Trang Vu
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA.
- Department of Chemical Engineering, Rowan University, Glassboro, NJ 08028, USA.
| | - Ye Xue
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA.
| | - Trinh Vuong
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
| | - Matthew Erbe
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
| | - Christopher Bennet
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
| | - Ben Palazzo
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
| | - Lucas Popielski
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
| | - Nelson Rodriguez
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
| | - Xiao Hu
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA.
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA.
- Department of Biomedical and Translational Sciences, Rowan University, Glassboro, NJ 08028, USA.
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17
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Reboleira ASPS, Enghoff H. Mud and silk in the dark: A new type of millipede moulting chamber and first observations on the maturation moult in the order Callipodida. Arthropod Struct Dev 2016; 45:301-306. [PMID: 27108528 DOI: 10.1016/j.asd.2016.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/04/2016] [Accepted: 04/08/2016] [Indexed: 06/05/2023]
Abstract
The postembryonic development of millipedes includes a series of stadia separated by moults, a process known as anamorphosis. The moulting process and especially the moulting into maturity, i.e., with fully developed copulatory organs, remains unknown for most millipede species. We have kept specimens of Lusitanipus alternans (Verhoeff, 1893) in the laboratory for one year and studied its moulting process, including the first study of the maturation moult in the order Callipodida. Unlike the typical silk cocoon reported for other callipodidans, this species builds a new type of solid moulting chamber, using the available substrate reinforced by a silken web. We present the detailed ultrastructure of the moulting chamber and silk. It takes five days to build the moulting chamber and between 29 (female) and 35 (male) days to shed the exuviae. The male maturation moult is preceded by an evagination of a gonopodal sac between the 6th and 7th body rings, in which the gonopods are developed. Females evaginated completely their vulval sacs, retracting them after shedding the exuviae. Vulval sac size seems to increase with the progressive reduction of the second pair of legs.
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Affiliation(s)
- Ana Sofia P S Reboleira
- Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, DK-2100 København Ø, Denmark.
| | - Henrik Enghoff
- Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, DK-2100 København Ø, Denmark
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18
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Chen F, Yang H, Liu X, Chen D, Xiao X, Liu K, Li J, Cheng F, Dong B, Zhou Y, Guo Z, Qin Y, Wang S, Xu W. Facile Fabrication of Multifunctional Hybrid Silk Fabrics with Controllable Surface Wettability and Laundering Durability. ACS Appl Mater Interfaces 2016; 8:5653-5660. [PMID: 26835541 DOI: 10.1021/acsami.5b11420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
To obtain a hydrophobic surface, TiO2 coatings are deposited on the surface of silk fabric using atomic layer deposition (ALD) to realize a hierarchical roughness structure. The surface morphology and topography, structure, and wettability properties of bare silk fabric and TiO2-coated silk fabrics thus prepared are evaluated using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), scanning probe microscope (SPM), X-ray diffraction (XRD), static water contact angles (WCAs), and roll-off angles, respectively. The surfaces of the silk fabrics with the TiO2 coatings exhibit higher surface roughnesses compared with those of the bare silk fabric. Importantly, the hydrophobic and laundering durability properties of the TiO2-coated silk fabrics are largely improved by increasing the thickness of the ALD TiO2 coating. Meanwhile, the ALD process has a litter effect on the service performance of silk fabric. Overall, TiO2 coating using an ALD process is recognized as a promising approach to produce hydrophobic surfaces for elastic materials.
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Affiliation(s)
- Fengxiang Chen
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University , Wuhan 430062, PR China
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
| | - Huiyu Yang
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
| | - Xin Liu
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
| | - Dongzhi Chen
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
| | - Xingfang Xiao
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
| | - Keshuai Liu
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
| | - Jing Li
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University , Wuhan 430062, PR China
| | - Fan Cheng
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University , Wuhan 430062, PR China
| | - Binhai Dong
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University , Wuhan 430062, PR China
| | - Yingshan Zhou
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
| | - Zhiguang Guo
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University , Wuhan 430062, PR China
| | - Yong Qin
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences , Taiyuan 030001, PR China
| | - Shimin Wang
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University , Wuhan 430062, PR China
| | - Weilin Xu
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University , Wuhan 430200, PR China
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19
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Joel AC, Kappel P, Adamova H, Baumgartner W, Scholz I. Cribellate thread production in spiders: Complex processing of nano-fibres into a functional capture thread. Arthropod Struct Dev 2015; 44:568-573. [PMID: 26248293 DOI: 10.1016/j.asd.2015.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/16/2015] [Accepted: 07/16/2015] [Indexed: 06/04/2023]
Abstract
Spider silk production has been studied intensively in the last years. However, capture threads of cribellate spiders employ an until now often unnoticed alternative of thread production. This thread in general is highly interesting, as it not only involves a controlled arrangement of three types of threads with one being nano-scale fibres (cribellate fibres), but also a special comb-like structure on the metatarsus of the fourth leg (calamistrum) for its production. We found the cribellate fibres organized as a mat, enclosing two parallel larger fibres (axial fibres) and forming the typical puffy structure of cribellate threads. Mat and axial fibres are punctiform connected to each other between two puffs, presumably by the action of the median spinnerets. However, this connection alone does not lead to the typical puffy shape of a cribellate thread. Removing the calamistrum, we found a functional capture thread still being produced, but the puffy shape of the thread was lost. Therefore, the calamistrum is not necessary for the extraction or combination of fibres, but for further processing of the nano-scale cribellate fibres. Using data from Uloborus plumipes we were able to develop a model of the cribellate thread production, probably universally valid for cribellate spiders.
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Affiliation(s)
- Anna-Christin Joel
- RWTH Aachen University, Institute of Biology II, Worringerweg 3, Germany.
| | - Peter Kappel
- RWTH Aachen University, Institute of Biology II, Worringerweg 3, Germany
| | - Hana Adamova
- RWTH Aachen University, Institute of Biology II, Worringerweg 3, Germany
| | - Werner Baumgartner
- JKU Linz, Institute of Biomedical Mechatronics, Altenberger Straße 69, Austria
| | - Ingo Scholz
- RWTH Aachen University, Institute of Biology II, Worringerweg 3, Germany
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20
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Xu D, Shi X, Thompson F, Weber WS, Mou Q, Yarger JL. Protein secondary structure of Green Lynx spider dragline silk investigated by solid-state NMR and X-ray diffraction. Int J Biol Macromol 2015; 81:171-9. [PMID: 26226457 PMCID: PMC4874476 DOI: 10.1016/j.ijbiomac.2015.07.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/23/2015] [Accepted: 07/24/2015] [Indexed: 01/22/2023]
Abstract
In this study, the secondary structure of the major ampullate silk from Peucetia viridans (Green Lynx) spiders is characterized by X-ray diffraction and solid-state NMR spectroscopy. From X-ray diffraction measurement, β-sheet nanocrystallites were observed and found to be highly oriented along the fiber axis, with an orientational order, fc≈0.98. The size of the nanocrystallites was determined to be on average 2.5nm×3.3nm×3.8nm. Besides a prominent nanocrystalline region, a partially oriented amorphous region was also observed with an fa≈0.89. Two-dimensional (13)C-(13)C through-space and through-bond solid-state NMR experiments were employed to elucidate structure details of P. viridans silk proteins. It reveals that β-sheet nanocrystallites constitutes 40.0±1.2% of the protein and are dominated by alanine-rich repetitive motifs. Furthermore, based upon the NMR data, 18±1% of alanine, 60±2% glycine and 54±2% serine are incorporated into helical conformations.
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Affiliation(s)
- Dian Xu
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Xiangyan Shi
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Forrest Thompson
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Warner S Weber
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Qiushi Mou
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Jeffery L Yarger
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States.
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21
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Xiao X, Liu X, Chen F, Fang D, Zhang C, Xia L, Xu W. Highly Anti-UV Properties of Silk Fiber with Uniform and Conformal Nanoscale TiO2 Coatings via Atomic Layer Deposition. ACS Appl Mater Interfaces 2015; 7:21326-21333. [PMID: 26389713 DOI: 10.1021/acsami.5b05868] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this study, silk fiber was successfully modified via the application of a nanoscale titania coating using atomic layer deposition (ALD), with titanium tetraisopropoxide (TIP) and water as precursors at 100 °C. Scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscope, and field emission scanning electron microscope results demonstrated that uniform and conformal titania coatings were deposited onto the silk fiber. The thermal and mechanical properties of the TiO2 silk fiber were then investigated. The results showed that the thermal stability and mechanical properties of this material were superior to those of the uncoated substance. Furthermore, the titania ALD process provided the silk fiber with excellent protection against UV radiation. Specifically, the TiO2-coated silk fibers exhibited significant increases in UV absorbance, considerably less yellowing, and greatly enhanced mechanical properties compared with the uncoated silk fiber after UV exposure.
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Affiliation(s)
- Xingfang Xiao
- Key Laboratory of Green Processing and Functional Textiles of New Textile Materials, Ministry of Science and Technology, Wuhan Textile University , Wuhan 430073, P. R. China
- College of Material Science and Engineering, Wuhan Institute of Technology , Wuhan 430073, P. R. China
| | - Xin Liu
- Key Laboratory of Green Processing and Functional Textiles of New Textile Materials, Ministry of Science and Technology, Wuhan Textile University , Wuhan 430073, P. R. China
| | - Fengxiang Chen
- Key Laboratory of Green Processing and Functional Textiles of New Textile Materials, Ministry of Science and Technology, Wuhan Textile University , Wuhan 430073, P. R. China
- Faculty of Materials Science and Engineering, Hubei University , Wuhan 430062, P. R. China
| | - Dong Fang
- Key Laboratory of Green Processing and Functional Textiles of New Textile Materials, Ministry of Science and Technology, Wuhan Textile University , Wuhan 430073, P. R. China
| | - Chunhua Zhang
- Key Laboratory of Green Processing and Functional Textiles of New Textile Materials, Ministry of Science and Technology, Wuhan Textile University , Wuhan 430073, P. R. China
| | - Liangjun Xia
- Key Laboratory of Green Processing and Functional Textiles of New Textile Materials, Ministry of Science and Technology, Wuhan Textile University , Wuhan 430073, P. R. China
| | - Weilin Xu
- Key Laboratory of Green Processing and Functional Textiles of New Textile Materials, Ministry of Science and Technology, Wuhan Textile University , Wuhan 430073, P. R. China
- College of Material Science and Engineering, Wuhan Institute of Technology , Wuhan 430073, P. R. China
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22
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Lin S, Ryu S, Tokareva O, Gronau G, Jacobsen MM, Huang W, Rizzo DJ, Li D, Staii C, Pugno NM, Wong JY, Kaplan DL, Buehler MJ. Predictive modelling-based design and experiments for synthesis and spinning of bioinspired silk fibres. Nat Commun 2015; 6:6892. [PMID: 26017575 PMCID: PMC4996357 DOI: 10.1038/ncomms7892] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Accepted: 03/10/2015] [Indexed: 11/08/2022] Open
Abstract
Scalable computational modelling tools are required to guide the rational design of complex hierarchical materials with predictable functions. Here, we utilize mesoscopic modelling, integrated with genetic block copolymer synthesis and bioinspired spinning process, to demonstrate de novo materials design that incorporates chemistry, processing and material characterization. We find that intermediate hydrophobic/hydrophilic block ratios observed in natural spider silks and longer chain lengths lead to outstanding silk fibre formation. This design by nature is based on the optimal combination of protein solubility, self-assembled aggregate size and polymer network topology. The original homogeneous network structure becomes heterogeneous after spinning, enhancing the anisotropic network connectivity along the shear flow direction. Extending beyond the classical polymer theory, with insights from the percolation network model, we illustrate the direct proportionality between network conductance and fibre Young's modulus. This integrated approach provides a general path towards de novo functional network materials with enhanced mechanical properties and beyond (optical, electrical or thermal) as we have experimentally verified.
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Affiliation(s)
- Shangchao Lin
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Mechanical Engineering, Materials Science and Engineering Program, Florida State University, Tallahassee, Florida 32310, USA
| | - Seunghwa Ryu
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-338, Korea
| | - Olena Tokareva
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Greta Gronau
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Institute for Particle Technology, Technische Universitat Braunschweig, Braunschweig 38104, Germany
| | - Matthew M Jacobsen
- Department of Biomedical Engineering and Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Wenwen Huang
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Daniel J Rizzo
- Department of Physics and Astronomy, Center for Nanoscopic Physics, Tufts University, Medford, Massachusetts 02155, USA
| | - David Li
- Department of Biomedical Engineering and Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Cristian Staii
- Department of Physics and Astronomy, Center for Nanoscopic Physics, Tufts University, Medford, Massachusetts 02155, USA
| | - Nicola M Pugno
- Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, I-38123 Trento, Italy
- Centre for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, I-38123 Trento, Italy
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Joyce Y Wong
- Department of Biomedical Engineering and Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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23
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Zhou S, Huang W, Belton DJ, Simmons LO, Perry CC, Wang X, Kaplan DL. Control of silicification by genetically engineered fusion proteins: silk-silica binding peptides. Acta Biomater 2015; 15:173-80. [PMID: 25462851 DOI: 10.1016/j.actbio.2014.10.040] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 10/26/2014] [Accepted: 10/29/2014] [Indexed: 11/18/2022]
Abstract
In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk-silica composite in two different bioinspired silicification systems: solution-solution and solution-solid. Condensed silica nanoscale particles (600-800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras, revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution-solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer-silica composites for biomaterial related needs.
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Affiliation(s)
- Shun Zhou
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, PR China; Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Wenwen Huang
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - David J Belton
- Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
| | - Leo O Simmons
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Carole C Perry
- Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
| | - Xiaoqin Wang
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, PR China; Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - David L Kaplan
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, PR China; Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA.
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24
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Zhang F, You X, Dou H, Liu Z, Zuo B, Zhang X. Facile fabrication of robust silk nanofibril films via direct dissolution of silk in CaCl2-formic acid solution. ACS Appl Mater Interfaces 2015; 7:3352-61. [PMID: 25603225 DOI: 10.1021/am508319h] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this study, we report for the first time a novel silk fibroin (SF) nanofibrous films with robust mechanical properties that was fabricated by directly dissolving silk in CaCl2-formic acid solution. CaCl2-FA dissolved silk rapidly at room temperature, and more importantly, it disintegrated silk into nanofibrils instead of separate molecules. The morphology of nanofibrils crucially depended on CaCl2 concentrations, which resulted in different aggregation nanostructure in SF films. The SF film after drawing had maximum elastic modulus, ultimate tensile strength, and strain at break reaching 4 GPa, 106 MPa, and 29%, respectively, in dry state and 206 MPa, 28 MPa, and 188%, respectively, in wet state. Moreover, multiple yielding phenomena and substantially strain-hardening behavior was also observed in the stretched films, indicating the important role played by preparation method in regulating the mechanical properties of SF films. These exceptional and unique mechanical properties were suggested to be caused by preserving silk nanofibril during dissolution and stretching to align these nanofibrils. Furthermore, the SF films exhibit excellent biocompatibility, supporting marrow stromal cells adhesion and proliferation. The film preparation was facile, and the resulting SF films manifested enhanced mechanical properties, unique nanofibrous structures, and good biocompability.
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Affiliation(s)
- Feng Zhang
- Medical College of Soochow University, Jiangsu Province Key Laboratory of Stem Cell Research, Soochow University , Suzhou 215123, China
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25
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Abstract
Top-down approaches based on etching techniques have almost reached their limits in terms of dimension. Therefore, novel assembly strategies and types of nanomaterials are required to allow technological advances. Self-assembly processes independent of external energy sources and unlimited in dimensional scaling have become a very promising approach. Here,we highlight recent developments in self-assembled DNA-polymer, silk-polymer and silk-DNA hybrids as promising materials with biotic and abiotic moieties for constructing complex hierarchical materials in ‘bottom-up’ approaches. DNA block copolymers assemble into nanostructures typically exposing a DNA corona which allows functionalization, labeling and higher levels of organization due to its specific addressable recognition properties. In contrast, self-assembly of natural silk proteins as well as their recombinant variants yields mechanically stable β-sheet rich nanostructures. The combination of silk with abiotic polymers gains hybrid materials with new functionalities. Together, the precision of DNA hybridization and robustness of silk fibrillar structures combine in novel conjugates enable processing of higher-order structures with nanoscale architecture and programmable functions.
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26
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Jiang P, Marí-Buyé N, Madurga R, Arroyo-Hernández M, Solanas C, Gañán A, Daza R, Plaza GR, Guinea GV, Elices M, Cenis JL, Pérez-Rigueiro J. Spider silk gut: development and characterization of a novel strong spider silk fiber. Sci Rep 2014; 4:7326. [PMID: 25475975 PMCID: PMC4256644 DOI: 10.1038/srep07326] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/19/2014] [Indexed: 11/09/2022] Open
Abstract
Spider silk fibers were produced through an alternative processing route that differs widely from natural spinning. The process follows a procedure traditionally used to obtain fibers directly from the glands of silkworms and requires exposure to an acid environment and subsequent stretching. The microstructure and mechanical behavior of the so-called spider silk gut fibers can be tailored to concur with those observed in naturally spun spider silk, except for effects related with the much larger cross-sectional area of the former. In particular spider silk gut has a proper ground state to which the material can revert independently from its previous loading history by supercontraction. A larger cross-sectional area implies that spider silk gut outperforms the natural material in terms of the loads that the fiber can sustain. This property suggests that it could substitute conventional spider silk fibers in some intended uses, such as sutures and scaffolds in tissue engineering.
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Affiliation(s)
- Ping Jiang
- College of Life Sciences, Jinggangshan University, Jiangxi Province, Ji'an. 343009, China
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
| | - Núria Marí-Buyé
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Rodrigo Madurga
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - María Arroyo-Hernández
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Concepción Solanas
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Alfonso Gañán
- Escuela Técnica Superior de Ingenieros. Universidad de Sevilla. 41092. Sevilla. Spain
| | - Rafael Daza
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Gustavo R. Plaza
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Gustavo V. Guinea
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Manuel Elices
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - José Luis Cenis
- Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario. 30150 La Alberca (Murcia). Spain
| | - José Pérez-Rigueiro
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain
- Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
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27
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Mortimer B, Gordon SD, Holland C, Siviour CR, Vollrath F, Windmill JFC. The speed of sound in silk: linking material performance to biological function. Adv Mater 2014; 26:5179-83. [PMID: 24902950 PMCID: PMC4140601 DOI: 10.1002/adma.201401027] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/25/2014] [Indexed: 05/31/2023]
Abstract
Sonic properties of spider silks are measured independent of the web using laser vibrometry and ballistic impact providing insights into Nature's design of functionalized high-performance materials. Through comparison to cocoon silk and other industrial fibers, we find that major ampullate silk has the largest wavespeed range of any known material.
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Affiliation(s)
- Beth Mortimer
- University of Oxford, Department of Zoology, Oxford, OX1 3PS, UK
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28
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Andersson M, Chen G, Otikovs M, Landreh M, Nordling K, Kronqvist N, Westermark P, Jörnvall H, Knight S, Ridderstråle Y, Holm L, Meng Q, Jaudzems K, Chesler M, Johansson J, Rising A. Carbonic anhydrase generates CO2 and H+ that drive spider silk formation via opposite effects on the terminal domains. PLoS Biol 2014; 12:e1001921. [PMID: 25093327 PMCID: PMC4122339 DOI: 10.1371/journal.pbio.1001921] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 06/26/2014] [Indexed: 11/18/2022] Open
Abstract
Spider silk fibers are produced from soluble proteins (spidroins) under ambient conditions in a complex but poorly understood process. Spidroins are highly repetitive in sequence but capped by nonrepetitive N- and C-terminal domains (NT and CT) that are suggested to regulate fiber conversion in similar manners. By using ion selective microelectrodes we found that the pH gradient in the silk gland is much broader than previously known. Surprisingly, the terminal domains respond in opposite ways when pH is decreased from 7 to 5: Urea denaturation and temperature stability assays show that NT dimers get significantly stabilized and then lock the spidroins into multimers, whereas CT on the other hand is destabilized and unfolds into ThT-positive β-sheet amyloid fibrils, which can trigger fiber formation. There is a high carbon dioxide pressure (pCO2) in distal parts of the gland, and a CO2 analogue interacts with buried regions in CT as determined by nuclear magnetic resonance (NMR) spectroscopy. Activity staining of histological sections and inhibition experiments reveal that the pH gradient is created by carbonic anhydrase. Carbonic anhydrase activity emerges in the same region of the gland as the opposite effects on NT and CT stability occur. These synchronous events suggest a novel CO2 and proton-dependent lock and trigger mechanism of spider silk formation.
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Affiliation(s)
- Marlene Andersson
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Gefei Chen
- Institute of Biological Sciences and Biotechnology, Donghua University, Shanghai, People's Republic of China
| | - Martins Otikovs
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Michael Landreh
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Kerstin Nordling
- Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet, Stockholm, Sweden
| | - Nina Kronqvist
- Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet, Stockholm, Sweden
| | - Per Westermark
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Hans Jörnvall
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Stefan Knight
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Yvonne Ridderstråle
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Lena Holm
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Qing Meng
- Institute of Biological Sciences and Biotechnology, Donghua University, Shanghai, People's Republic of China
- * E-mail: (J.J.); (Q.M.); (A.R.)
| | - Kristaps Jaudzems
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Mitchell Chesler
- Departments of Neurosurgery, Physiology and Neuroscience, New York University School of Medicine, New York, New York, United States of America
| | - Jan Johansson
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet, Stockholm, Sweden
- Institute of Mathematics and Natural Sciences, Tallinn University, Tallinn, Estonia
- * E-mail: (J.J.); (Q.M.); (A.R.)
| | - Anna Rising
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet, Stockholm, Sweden
- * E-mail: (J.J.); (Q.M.); (A.R.)
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29
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Humenik M, Drechsler M, Scheibel T. Controlled hierarchical assembly of spider silk-DNA chimeras into ribbons and raft-like morphologies. Nano Lett 2014; 14:3999-4004. [PMID: 24924514 DOI: 10.1021/nl501412k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Spider silk-DNA conjugates comprising the recombinant spider silk protein eADF4(C16) and short oligonucleotides were arranged in a linear antiparallel and parallel as well as in a branched manner via designed complementarity of the DNA moieties. After cross-β fibril self-assembly, temperature-induced annealing of the DNA moieties triggered fibril association into ribbons, composed of aligned nanofibrils, and rafts composed of ribbons ordered into sharply bordered, squared fibrous microstructures. The formation of the superstructures was clearly dependent on the individual silk-DNA conjugate. A combination of 5'-conjugated silk moieties via complementary nucleic acids enhanced fibril association, whereas mixing complementary 5'- and 3'-silk conjugates inhibited the formation of higher-order structures.
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Affiliation(s)
- Martin Humenik
- Biomaterials, Faculty of Engineering Science, ‡Bayreuth Institute of Macromolecular Research (BIMF) - Soft Matter Electron Microscopy, and §Bayreuth Center for Colloids and Interfaces (BZKG), Research Center Bio-Macromolecules (BIOmac), Bayreuth Center for Molecular Biosciences (BZMB), and Bayreuth Center for Material Science (BayMAT), University of Bayreuth , D-95440 Bayreuth, Germany
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30
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Tulachan B, Meena SK, Rai RK, Mallick C, Kusurkar TS, Teotia AK, Sethy NK, Bhargava K, Bhattacharya S, Kumar A, Sharma RK, Sinha N, Singh SK, Das M. Electricity from the silk cocoon membrane. Sci Rep 2014; 4:5434. [PMID: 24961354 PMCID: PMC4069722 DOI: 10.1038/srep05434] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 06/05/2014] [Indexed: 11/16/2022] Open
Abstract
Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management.
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Affiliation(s)
- Brindan Tulachan
- Bioelectricity, Green Energy, Physiology & Sensor Group, Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
- These authors contributed equally to this work
| | - Sunil Kumar Meena
- Electrical Engineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
- These authors contributed equally to this work
| | - Ratan Kumar Rai
- Center for Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow, UP, 226014, India
| | - Chandrakant Mallick
- Bioelectricity, Green Energy, Physiology & Sensor Group, Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
| | - Tejas Sanjeev Kusurkar
- Bioelectricity, Green Energy, Physiology & Sensor Group, Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
| | - Arun Kumar Teotia
- Department of Biological Sciences and Bioengineering & Center for Environmental Sciences and Engineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
| | - Niroj Kumar Sethy
- Peptide and Proteomics Unit, Defense Institute Physiology and Allied Sciences, Defense Research Development Organization, Delhi, 110054, India
| | - Kalpana Bhargava
- Peptide and Proteomics Unit, Defense Institute Physiology and Allied Sciences, Defense Research Development Organization, Delhi, 110054, India
| | - Shantanu Bhattacharya
- Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
| | - Ashok Kumar
- Department of Biological Sciences and Bioengineering & Center for Environmental Sciences and Engineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
| | | | - Neeraj Sinha
- Center for Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow, UP, 226014, India
| | - Sushil Kumar Singh
- Functional Materials Group, Solid State Physics Laboratory, Defense Research Development Organization, Delhi, 110054, India
| | - Mainak Das
- Bioelectricity, Green Energy, Physiology & Sensor Group, Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
- Design Program, Indian Institute of Technology Kanpur, Kanpur, UP, 208016, India
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31
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Han F, Liu S, Liu X, Pei Y, Bai S, Zhao H, Lu Q, Ma F, Kaplan DL, Zhu H. Woven silk fabric-reinforced silk nanofibrous scaffolds for regenerating load-bearing soft tissues. Acta Biomater 2014; 10:921-30. [PMID: 24090985 DOI: 10.1016/j.actbio.2013.09.026] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 09/03/2013] [Accepted: 09/23/2013] [Indexed: 11/19/2022]
Abstract
Although three-dimensional (3-D) porous regenerated silk scaffolds with outstanding biocompatibility, biodegradability and low inflammatory reactions have promising application in different tissue regeneration, the mechanical properties of regenerated scaffolds, especially suture retention strength, must be further improved to satisfy the requirements of clinical applications. This study presents woven silk fabric-reinforced silk nanofibrous scaffolds aimed at dermal tissue engineering. To improve the mechanical properties, silk scaffolds prepared by lyophilization were reinforced with degummed woven silk fabrics. The ultimate tensile strength, elongation at break and suture retention strength of the scaffolds were significantly improved, providing suitable mechanical properties strong enough for clinical applications. The stiffness and degradation behaviors were then further regulated by different after-treatment processes, making the scaffolds more suitable for dermal tissue regeneration. The in vitro cell culture results indicated that these scaffolds maintained their excellent biocompatibility after being reinforced with woven silk fabrics. Without sacrifice of porous structure and biocompatibility, the fabric-reinforced scaffolds with better mechanical properties could facilitate future clinical applications of silk as matrices in skin repair.
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Affiliation(s)
- F Han
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China; Key Lab of Rubber-Plastics (QUST), Ministry of Education, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - S Liu
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China
| | - X Liu
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China
| | - Y Pei
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China
| | - S Bai
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China
| | - H Zhao
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China
| | - Q Lu
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China.
| | - F Ma
- Key Lab of Rubber-Plastics (QUST), Ministry of Education, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
| | - D L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - H Zhu
- Research Center of Materials Science, Beijing Institute of Technology, Beijing 100081, China
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32
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Abstract
We propose a biocompatible hybrid photonic platform incorporating a 3D silk inverse opal (SIO) crystal and a 2D plasmonic crystal formed on the top surface of the SIO. This hybrid photonic-plasmonic crystal (HPPC) structure simultaneously exhibits both an extraordinary transmission and a pseudo-photonic band-gap in its transmission spectrum. We demonstrate the use of the HPPC as a refractive index (RI) sensor. By performing a multispectral analysis to analyze the RI value, a sensitivity of 200,000 nm·Δ%T/RIU (refractive index unit) is achieved.
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Affiliation(s)
- Sunghwan Kim
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
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33
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Rodbumrer P, Arthan D, Uyen U, Yuvaniyama J, Svasti J, Wongsaengchantra PY. Functional expression of a Bombyx mori cocoonase: potential application for silk degumming. Acta Biochim Biophys Sin (Shanghai) 2012; 44:974-83. [PMID: 23169343 DOI: 10.1093/abbs/gms090] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cocoon, a shelter for larva development to silk moth, contains the fibrous protein fibroin, which is coated by the globular protein sericin. Emergence of the silk moth requires the action of cocoonase, a protease secreted by the pupa. The full-length prococoonase cDNA, with 780 bp open reading frame encoding 260 amino acids, was cloned by reverse transcription from total RNA of the head of 6-day-old Thai-silk Bombyx mori pupa. Only the gene fragment lacking the propeptide encoding sequence was successfully expressed in Pichia pastoris, yielding an extracellularly active cocoonase. The recombinant cocoonase was purified to homogeneity by 80% ammonium-sulfate fractionation and CM-Sepharose chromatography, and its internal peptide sequences were analyzed by nano liquid chromatography-mass spectrometry/mass spectrometry. This monomeric protein has native molecular weight of 26 kDa by gel exclusion analysis and 25 kDa subunit size by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The enzyme hydrolyses sericin but does not hydrolyse fibroin, as shown by radial diffusion on thin-layer enzyme assay (RD-TEA). Scanning electron microscopy showed that purified recombinant cocoonase could remove sericin from natural silk completely in 24 h, without damaging fibroin, using only 1 immobilized sericin unit (ISU) of enzyme as determined by RD-TEA. Natural cocoonase isolated from B. mori pupa could also digest sericin effectively, but required more enzymes (2 ISU) and longer time (48 h). In comparison, a commercial enzyme, alcalase, with the same activity not only showed less complete digestion of sericin but also caused damage of fibroin. These results suggest that recombinant B. mori cocoonase is potentially useful for silk degumming.
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Affiliation(s)
- Prangprapai Rodbumrer
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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34
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Lin D, Tao H, Trevino J, Mondia JP, Kaplan DL, Omenetto FG, Dal Negro L. Direct transfer of subwavelength plasmonic nanostructures on bioactive silk films. Adv Mater 2012; 24:6088-6093. [PMID: 22941856 DOI: 10.1002/adma.201201888] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/11/2012] [Indexed: 06/01/2023]
Abstract
By a reusable transfer fabrication technique, we demonstrate high-fidelity fabrication of metal nanoparticles, optical nanoantennas, and nanohole arrays directly on a functional silk biopolymer. The ability to reproducibly pattern silk biopolymers with arbitrarily complex plasmonic arrays is of importance for a variety of applications in optical biosensing, tissue engineering, cell biology, and the development of novel bio-optoelectronic medical devices.
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Affiliation(s)
- Dianmin Lin
- Department of Electrical and Computer Engineering & Photonic Center, Boston University, Boston, MA 02215, USA
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35
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Abstract
3D silk/HA microperiodic scaffolds for bone tissue engineering and angiogenesis are fabricated by direct-write assembly. This approach can be used to control filament and spacing size in the scaffold to allow investigation of the effect of scaffold architecture on osteogenesis and vessel-like structure formation from stem cells and endothelial cells.
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Affiliation(s)
- Lin Sun
- Department of Chemical and Biological Engineering and Biomedical Engineering, Tufts University, Medford, MA 02155, USA
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36
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Lawrence BD, Pan Z, Liu A, Kaplan DL, Rosenblatt MI. Human corneal limbal epithelial cell response to varying silk film geometric topography in vitro. Acta Biomater 2012; 8:3732-43. [PMID: 22705042 DOI: 10.1016/j.actbio.2012.06.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 04/26/2012] [Accepted: 06/07/2012] [Indexed: 12/15/2022]
Abstract
Silk fibroin films are a promising class of biomaterials that have a number of advantages for use in ophthalmic applications due to their transparent nature, mechanical properties and minimal inflammatory response upon implantation. Freestanding silk films with parallel line and concentric ring topographies were generated for in vitro characterization of human corneal limbal epithelial (HCLE) cell response upon differing geometric patterned surfaces. Results indicated that silk film topography significantly affected initial HCLE culture substrate attachment, cellular alignment, cell-to-cell contact formation, actin cytoskeleton alignment and focal adhesion (FA) localization. Most notably, parallel line patterned surfaces displayed a 36-54% increase on average in initial cell attachment, which corresponded to a more than 2-fold increase in FA localization when compared to other silk film surfaces and controls. In addition, distinct localization of FA formation was observed along the edges for all patterned silk film topographies. In conclusion, silk film feature topography appears to help direct corneal epithelial cell response and cytoskeleton development, especially with regard to FA distribution, in vitro.
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Affiliation(s)
- Brian D Lawrence
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA
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37
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Abstract
Nanofibrous Bacterial cellulose nanocrystals (BCNs)-embedded silk fibroin were successfully fabricated using electrospinning. The morphology, structure and mechanical properties of the silk fibroin nanofibers were investigated at various BCNs concentrations from 0 to 7 wt%. SEM, TEM and XRD analyses were conducted to confirm the incorporation of the BCNs in the electrospun silk fibroin nanofibers. The average diameter of the silk fibroin/BCNs nanofibers increased from 230 to 430 nm according to the increasing of the BCNs ratio due to the rising solute content. The FT-IR spectra confirmed the conformational transition of the silk fibroin, from a random coil to a beta-sheet structure, which shows the enhanced mechanical properties of silk fibroin based nanofibers even with small amounts of the BCNs. Moreover, it was observed that the Young's modulus of the silk fibroin/BCNs nanofibers unexpectedly increased with the formation of BCNs with a percolation structure at a concentration between 3 and 5 wt%.
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Affiliation(s)
- Doo Jin Park
- Department of Polymer Science and Engineering, Inha University, Incheon 402-751, Korea
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Oliveira AL, Sun L, Kim HJ, Hu X, Rice W, Kluge J, Reis RL, Kaplan DL. Aligned silk-based 3-D architectures for contact guidance in tissue engineering. Acta Biomater 2012; 8:1530-42. [PMID: 22202909 DOI: 10.1016/j.actbio.2011.12.015] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/24/2011] [Accepted: 12/09/2011] [Indexed: 01/15/2023]
Abstract
An important challenge in the biomaterials field is to mimic the structure of functional tissues via cell and extracellular matrix (ECM) alignment and anisotropy. Toward this goal, silk-based scaffolds resembling bone lamellar structure were developed using a freeze-drying technique. The structure could be controlled directly by solute concentration and freezing parameters, resulting in lamellar scaffolds with regular morphology. Different post-treatments, such as methanol, water annealing and steam sterilization, were investigated to induce water stability. The resulting structures exhibited significant differences in terms of morphological integrity, structure and mechanical properties. The lamellar thicknesses were ∼2.6 μm for the methanol-treated scaffolds and ∼5.8 μm for water-annealed. These values are in the range of those reported for human lamellar bone. Human bone marrow-derived mesenchymal stem cells (hMSC) were seeded on these silk fibroin lamellar scaffolds and grown under osteogenic conditions to assess the effect of the microstructure on cell behavior. Collagen in the newly deposited ECM was found aligned along the lamellar architectures. In the case of methanol-treated lamellar structures, the hMSC were able to migrate into the interior of the scaffolds, producing a multilamellar hybrid construct. The present morphology constitutes a useful pattern onto which hMSC cells attach and proliferate for guided formation of a highly oriented extracellular matrix.
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Affiliation(s)
- A L Oliveira
- 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimarães, Portugal.
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Lepore E, Marchioro A, Isaia M, Buehler MJ, Pugno NM. Evidence of the most stretchable egg sac silk stalk, of the European spider of the year Meta menardi. PLoS One 2012; 7:e30500. [PMID: 22347380 PMCID: PMC3275603 DOI: 10.1371/journal.pone.0030500] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 12/16/2011] [Indexed: 11/29/2022] Open
Abstract
Spider silks display generally strong mechanical properties, even if differences between species and within the same species can be observed. While many different types of silks have been tested, the mechanical properties of stalks of silk taken from the egg sac of the cave spider Meta menardi have not yet been analyzed. Meta menardi has recently been chosen as the "European spider of the year 2012", from the European Society of Arachnology. Here we report a study where silk stalks were collected directly from several caves in the north-west of Italy. Field emission scanning electron microscope (FESEM) images showed that stalks are made up of a large number of threads, each of them with diameter of 6.03 ± 0.58 µm. The stalks were strained at the constant rate of 2 mm/min, using a tensile testing machine. The observed maximum stress, strain and toughness modulus, defined as the area under the stress-strain curve, are 0.64 GPa, 751% and 130.7 MJ/m(3), respectively. To the best of our knowledge, such an observed huge elongation has never been reported for egg sac silk stalks and suggests a huge unrolling microscopic mechanism of the macroscopic stalk that, as a continuation of the protective egg sac, is expected to be composed by fibres very densely and randomly packed. The Weibull statistics was used to analyze the results from mechanical testing, and an average value of Weibull modulus (m) is deduced to be in the range of 1.5-1.8 with a Weibull scale parameter (σ(0)) in the range of 0.33-0.41 GPa, showing a high coefficient of correlation (R(2) = 0.97).
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Affiliation(s)
- Emiliano Lepore
- Laboratory of Bio-inspired Nanomechanics “Giuseppe Maria Pugno”, Department of Structural Engineering, Politecnico di Torino, Torino, Italy
| | - Andrea Marchioro
- Laboratory of Bio-inspired Nanomechanics “Giuseppe Maria Pugno”, Department of Structural Engineering, Politecnico di Torino, Torino, Italy
| | - Marco Isaia
- Laboratory of Ecology and Terrestrial Ecosystems, Department of Human and Animal Biology, University of Torino, Torino, Italy
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Center for Materials Science and Engineering, and Center for Computational Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Nicola M. Pugno
- Laboratory of Bio-inspired Nanomechanics “Giuseppe Maria Pugno”, Department of Structural Engineering, Politecnico di Torino, Torino, Italy
- National Institute of Nuclear Physics, National Laboratories of Frascati, Frascati, Italy
- National Institute of Metrological Research, Torino, Italy
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Beun LH, Beaudoux XJ, Kleijn JM, de Wolf FA, Stuart MAC. Self-assembly of silk-collagen-like triblock copolymers resembles a supramolecular living polymerization. ACS Nano 2012; 6:133-140. [PMID: 22168567 DOI: 10.1021/nn203092u] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We produced several pH-responsive silk-collagen-like triblocks, one acidic and two alkaline. At pH values where the silk-like block is uncharged the triblocks self-assemble into filaments. The pH-induced self-assembly was examined by atomic force microscopy, light scattering, and circular dichroism. The populations of filaments were found to be very monodisperse, indicating that the filaments start to grow from already present nuclei in the sample. The growth then follows pseudo-first-order kinetics for all examined triblocks. When normalized to the initial concentration, the growth curves of each type of triblock overlap, showing that the self-assembly is a generic process for silk-collagen-silk triblocks, regardless of the nature of their chargeable groups. The elongation speed of the filaments is slow, due to the presence of repulsive collagen-like blocks and the limited number of possibilities for an approaching triblock to successfully attach to a growing end. The formation of filaments is fully reversible. Already present filaments can start growing again by addition of new triblocks. The structure of all filaments is very rich in β-turns, leading to β-rolls. The triblocks attain this structure only when attaching to a growing filament.
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Affiliation(s)
- Lennart H Beun
- Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB, Wageningen, The Netherlands.
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41
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Giesa T, Arslan M, Pugno NM, Buehler MJ. Nanoconfinement of spider silk fibrils begets superior strength, extensibility, and toughness. Nano Lett 2011; 11:5038-5046. [PMID: 21967633 DOI: 10.1021/nl203108t] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Silk is an exceptionally strong, extensible, and tough material made from simple protein building blocks. The molecular structure of dragline spider silk repeat units consists of semiamorphous and nanocrystalline β-sheet protein domains. Here we show by a series of computational experiments how the nanoscale properties of silk repeat units are scaled up to create macroscopic silk fibers with outstanding mechanical properties despite the presence of cavities, tears, and cracks. We demonstrate that the geometric confinement of silk fibrils to diameters of 50 ± 30 nm is critical to facilitate a powerful mechanism by which hundreds of thousands of protein domains synergistically resist deformation and failure to provide enhanced strength, extensibility, and toughness at the macroscale, closely matching experimentally measured mechanical properties. Through this mechanism silk fibers exploit the full potential of the nanoscale building blocks, regardless of the details of microscopic loading conditions and despite the presence of large defects. Experimental results confirm that silk fibers are composed of silk fibril bundles with diameters in the range of 20-150 nm, in agreement with our predicted length scale. Our study reveals a general mechanism to map nanoscale properties to the macroscale and provides a potent design strategy toward novel fiber and bulk nanomaterials through hierarchical structures.
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Affiliation(s)
- Tristan Giesa
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-235A&B, Cambridge, Massachusetts 02139, United States
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42
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Wu C, Zhang Y, Zhou Y, Fan W, Xiao Y. A comparative study of mesoporous glass/silk and non-mesoporous glass/silk scaffolds: physiochemistry and in vivo osteogenesis. Acta Biomater 2011; 7:2229-36. [PMID: 21185954 DOI: 10.1016/j.actbio.2010.12.019] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 12/14/2010] [Accepted: 12/20/2010] [Indexed: 12/24/2022]
Abstract
Mesoporous bioactive glass (MBG) is a new class of biomaterials with a well-ordered nanochannel structure, whose in vitro bioactivity is far superior than that of non-mesoporous bioactive glass (BG); the material's in vivo osteogenic properties are, however, yet to be assessed. Porous silk scaffolds have been used for bone tissue engineering, but this material's osteoconductivity is far from optimal. The aims of this study were to incorporate MBG into silk scaffolds in order to improve their osteoconductivity and then to compare the effect of MBG and BG on the in vivo osteogenesis of silk scaffolds. MBG/silk and BG/silk scaffolds with a highly porous structure were prepared by a freeze-drying method. The mechanical strength, in vitro apatite mineralization, silicon ion release and pH stability of the composite scaffolds were assessed. The scaffolds were implanted into calvarial defects in SCID mice and the degree of in vivo osteogenesis was evaluated by microcomputed tomography (μCT), hematoxylin and eosin (H&E) and immunohistochemistry (type I collagen) analyses. The results showed that MBG/silk scaffolds have better physiochemical properties (mechanical strength, in vitro apatite mineralization, Si ion release and pH stability) compared to BG/silk scaffolds. MBG and BG both improved the in vivo osteogenesis of silk scaffolds. μCT and H&E analyses showed that MBG/silk scaffolds induced a slightly higher rate of new bone formation in the defects than did BG/silk scaffolds and immunohistochemical analysis showed greater synthesis of type I collagen in MBG/silk scaffolds compared to BG/silk scaffolds.
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Affiliation(s)
- Chengtie Wu
- Institute of Health & Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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43
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Brown CP, Rosei F, Traversa E, Licoccia S. Spider silk as a load bearing biomaterial: tailoring mechanical properties via structural modifications. Nanoscale 2011; 3:870-876. [PMID: 21212901 DOI: 10.1039/c0nr00752h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Spider silk shows great potential as a biomaterial: in addition to biocompatibility and biodegradability, its strength and toughness are greater than native biological fibres (e.g. collagen), with toughness exceeding that of synthetic fibres (e.g. nylon). Although the ultimate tensile strength and toughness at failure are unlikely to be limiting factors, its yield strain of 2% is insufficient, particularly for biomedical application because of the inability to mimic the complex ultrastructure of natural tissues with current tissue engineering approaches. To harness the full potential of spider silk as a biomaterial, it is therefore necessary to increase its yield strain. In this paper, we discuss the means by which the mechanical properties of spider silk, particularly the yield strain, can be optimized through structural modifications.
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Affiliation(s)
- Cameron P Brown
- Centro NAST, Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, via Della Ricerca Scientifica, 000133, Roma, Italy.
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44
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Keten S, Buehler MJ. Nanostructure and molecular mechanics of spider dragline silk protein assemblies. J R Soc Interface 2010; 7:1709-21. [PMID: 20519206 PMCID: PMC2988266 DOI: 10.1098/rsif.2010.0149] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2010] [Accepted: 05/12/2010] [Indexed: 11/12/2022] Open
Abstract
Spider silk is a self-assembling biopolymer that outperforms most known materials in terms of its mechanical performance, despite its underlying weak chemical bonding based on H-bonds. While experimental studies have shown that the molecular structure of silk proteins has a direct influence on the stiffness, toughness and failure strength of silk, no molecular-level analysis of the nanostructure and associated mechanical properties of silk assemblies have been reported. Here, we report atomic-level structures of MaSp1 and MaSp2 proteins from the Nephila clavipes spider dragline silk sequence, obtained using replica exchange molecular dynamics, and subject these structures to mechanical loading for a detailed nanomechanical analysis. The structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly beta-sheet crystal domains, while disorderly regions are formed by glycine-rich repeats that consist of 3₁-helix type structures and beta-turns. Our structural predictions are validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots, alpha-carbon atomic distances, as well as secondary structure content. Mechanical shearing simulations on selected structures illustrate that the nanoscale behaviour of silk protein assemblies is controlled by the distinctly different secondary structure content and hydrogen bonding in the crystalline and semi-amorphous regions. Both structural and mechanical characterization results show excellent agreement with available experimental evidence. Our findings set the stage for extensive atomistic investigations of silk, which may contribute towards an improved understanding of the source of the strength and toughness of this biological superfibre.
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Affiliation(s)
- Sinan Keten
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave. Room 1-235A&B, Cambridge, MA, USA
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave. Room 1-235A&B, Cambridge, MA, USA
- Center for Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
- Center for Computational Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
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45
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Khan MR, Tsukada M, Gotoh Y, Morikawa H, Freddi G, Shiozaki H. Physical properties and dyeability of silk fibers degummed with citric acid. Bioresour Technol 2010; 101:8439-8445. [PMID: 20598526 DOI: 10.1016/j.biortech.2010.05.100] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 04/29/2010] [Accepted: 05/31/2010] [Indexed: 05/29/2023]
Abstract
Silk fibers from Bombyx mori silkworm was degummed with different concentration of citric acid, and the physical properties and fine structure were investigated to elucidate the effects of citric acid treatment. The silk sericin removal percentage was almost 100% after degumming with 30% citric acid which resulted in a total weight loss of 25.4% in the silk fibers. The surface morphology of silk fiber degummed with citric acid was very smooth and fine, showed perfect degumming like traditional soap-alkali method. The tensile strength of silk fiber was increased after degumming with citric acid (507MPa), where as the traditional soap-alkali method causes to decrease the strength about half of the control silk fiber (250MPa). The molecular conformation estimated by Fourier transform infrared spectroscopy and the crystalline structure evaluated from X-ray diffraction curve stayed unchanged regardless of the degumming with citric acid and soap. The dye uptake percentage of silk fiber degummed with citric acid decreased slightly, about 4.2%. On the other hand, the dye uptake percentage of silk degummed with soap was higher which indicates the disordering of the molecular orientation of the laterally ordered structure, accompanied with the partial hydrolysis of silk fibroin molecules by the alkali action of soap. The thermal properties were greatly enhanced by soap and citric acid degumming agents. Dynamic mechanical thermal analysis showed silk degummed with citric acid is more stable in higher temperature than that of soap. With heating at above 300 degrees C, the silk degummed with citric acid shows an increase in storage modulus and an onset of tan delta peaks at 325 degrees C and the melt flow of the sample was inhibited. The degumming of silk fibers with citric acid is safe and the results obtained are quite promising as a basis for possible future industrial application.
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Affiliation(s)
- Majibur Rahman Khan
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, Manitoba, Canada R3T 5V6
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46
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Abstract
Much spider silk research to date has focused on its mechanical properties. However, the webs of many orb-web spiders have evolved for over 136 million years to evade visual detection by insect prey. It is therefore a photonic device in addition to being a mechanical device. Herein we use optical surface profiling of capture silks from the webs of adult female St Andrews cross spiders (Argiope keyserlingi) to successfully measure the geometry of adhesive silk droplets and to show a bowing in the aqueous layer on the spider capture silk between adhesive droplets. Optical surface profiling shows geometric features of the capture silk that have not been previously measured and contributes to understanding the links between the physical form and biological function. The research also demonstrates non-standard use of an optical surface profiler to measure the maximum width of a transparent micro-sized droplet (microlens).
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Affiliation(s)
- D M Kane
- Department of Physics, Macquarie University, Sydney, NSW, Australia.
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47
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Lu Q, Hu X, Wang X, Kluge JA, Lu S, Cebe P, Kaplan DL. Water-insoluble silk films with silk I structure. Acta Biomater 2010; 6:1380-7. [PMID: 19874919 PMCID: PMC2830340 DOI: 10.1016/j.actbio.2009.10.041] [Citation(s) in RCA: 372] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 10/17/2009] [Accepted: 10/22/2009] [Indexed: 01/26/2023]
Abstract
Water-insoluble regenerated silk materials are normally produced by increasing the beta-sheet content (silk II). In the present study water-insoluble silk films were prepared by controlling the very slow drying of Bombyx mori silk solutions, resulting in the formation of stable films with a predominant silk I instead of silk II structure. Wide angle X-ray scattering indicated that the silk films stabilized by slow drying were mainly composed of silk I rather than silk II, while water- and methanol-annealed silk films had a higher silk II content. The silk films prepared by slow drying had a globule-like structure at the core surrounded by nano-filaments. The core region was composed of silk I and silk II, surrounded by hydrophilic nano-filaments containing random turns and alpha-helix secondary structures. The insoluble silk films prepared by slow drying had unique thermal, mechanical and degradative properties. Differential scanning calorimetry results revealed that silk I crystals had stable thermal properties up to 250 degrees C, without crystallization above the T(g), but degraded at lower temperatures than silk II structure. Compared with water- and methanol-annealed films the films prepared by slow drying had better mechanical ductility and were more rapidly enzymatically degraded, reflecting the differences in secondary structure achieved via differences in post processing of the cast silk films. Importantly, the silk I structure, a key intermediate secondary structure for the formation of mechanically robust natural silk fibers, was successfully generated by the present approach of very slow drying, mimicking the natural process. The results also point to a new mode of generating new types of silk biomaterials with enhanced mechanical properties and increased degradation rates, while maintaining water insolubility, along with a low beta-sheet content.
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Affiliation(s)
- Qiang Lu
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Xiao Hu
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Xiaoqin Wang
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Jonathan A. Kluge
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Shenzhou Lu
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou, 215021, P.R. China
| | - Peggy Cebe
- Department of Physics and Astronomy, Tufts University, Medford, MA 02155
| | - David L. Kaplan
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou, 215021, P.R. China
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48
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Meinel AJ, Kubow KE, Klotzsch E, Garcia-Fuentes M, Smith ML, Vogel V, Merkle HP, Meinel L. Optimization strategies for electrospun silk fibroin tissue engineering scaffolds. Biomaterials 2009; 30:3058-67. [PMID: 19233463 PMCID: PMC3792584 DOI: 10.1016/j.biomaterials.2009.01.054] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 01/29/2009] [Indexed: 12/30/2022]
Abstract
As a contribution to the functionality of scaffolds in tissue engineering, here we report on advanced scaffold design through introduction and evaluation of topographical, mechanical and chemical cues. For scaffolding, we used silk fibroin (SF), a well-established biomaterial. Biomimetic alignment of fibers was achieved as a function of the rotational speed of the cylindrical target during electrospinning of a SF solution blended with polyethylene oxide. Seeding fibrous SF scaffolds with human mesenchymal stem cells (hMSCs) demonstrated that fiber alignment could guide hMSC morphology and orientation demonstrating the impact of scaffold topography on the engineering of oriented tissues. Beyond currently established methodologies to measure bulk properties, we assessed the mechanical properties of the fibers by conducting extension at breakage experiments on the level of single fibers. Chemical modification of the scaffolds was tested using donor/acceptor fluorophore labeled fibronectin. Fluorescence resonance energy transfer imaging allowed to assess the conformation of fibronectin when adsorbed on the SF scaffolds, and demonstrated an intermediate extension level of its subunits. Biological assays based on hMSCs showed enhanced cellular adhesion and spreading as a result of fibronectin adsorbed on the scaffolds. Our studies demonstrate the versatility of SF as a biomaterial to engineer modified fibrous scaffolds and underscore the use of biofunctionally relevant analytical assays to optimize fibrous biomaterial scaffolds.
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Affiliation(s)
- Anne J Meinel
- Institute of Pharmaceutical Sciences, ETH Zurich, Department for Chemistry and Applied Biosciences, HCI J 390.1, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland.
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49
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Tomczak MM, Gupta MK, Drummy LF, Rozenzhak SM, Naik RR. Morphological control and assembly of zinc oxide using a biotemplate. Acta Biomater 2009; 5:876-82. [PMID: 19117819 DOI: 10.1016/j.actbio.2008.11.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 10/20/2008] [Accepted: 11/13/2008] [Indexed: 11/28/2022]
Abstract
Zinc oxide is a wide band gap material that has significant applications in photovoltaics, piezoelectrics and optoelectronics. Traditionally, ZnO has been synthesized using high temperatures and harsh reaction conditions. Recently, benign reaction conditions have been used to synthesize ZnO using amine and citrate additives. In this study, peptide phage display was performed to identify a peptide, termed Z1, that binds to and directs the growth of ZnO hexagonal nanocrystals. By altering the concentration of Z1 peptide, the ZnO nanocrystal morphology can be tailored. Additionally, Z1 peptide was used to direct the growth of ZnO structures on free-standing silk films. The results presented here demonstrate the utility of peptides in controlling the structure and deposition of ZnO.
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Affiliation(s)
- Melanie M Tomczak
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
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50
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Jeong L, Yeo IS, Kim HN, Yoon YI, Jang DH, Jung SY, Min BM, Park WH. Plasma-treated silk fibroin nanofibers for skin regeneration. Int J Biol Macromol 2008; 44:222-8. [PMID: 19150367 DOI: 10.1016/j.ijbiomac.2008.12.008] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 12/12/2008] [Accepted: 12/12/2008] [Indexed: 11/30/2022]
Abstract
Silk fibroin (SF) nanofibers were prepared by electrospinning and treated with plasma in the presence of oxygen or methane gas to modify their surface characteristics. The surface characteristics of the SF nanofibers after plasma treatment were examined using contact angle measurements and XPS analysis. The hydrophilicity of the electrospun SF nanofibers decreased slightly by the CH(4) plasma treatment. On the other hand, the hydrophilicity of the SF nanofibers increased greatly by an O(2) plasma treatment. The O(2)-treated SF nanofibers showed higher cellular activities for both normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF) than the untreated ones.
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Affiliation(s)
- Lim Jeong
- Department of Advanced Organic Materials and Textile System Engineering, Chungnam National University, Daejeon, Republic of Korea
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