Silk Proteins for Biomedical Applications

A special issue of Journal of Functional Biomaterials (ISSN 2079-4983).

Deadline for manuscript submissions: closed (27 June 2017) | Viewed by 40375

Special Issue Editor

Special Issue Information

Dear Colleagues,

Silk proteins are one of the most important biological macromolecules that have been used as materials for centuries, due to their lustre, being light weight, their tear resistance, and great economic importance. Silk materials are environmentally friendly, renewable, and non-toxic, with excellent strength, elongation, toughness, and slow degradability. Synthesized by the larva of different insects (e.g., silkworms, spiders, bees, and ants), silk proteins can form different structures, including beta-pleated sheets, coiled coils, or twisted-hellices. Due to their distinctive properties, silk materials can be fabricated into films, fibers, sponges, gels, and particles, as well as thermal, optical, and electrical devices. Such material systems provide advantages in comparison with traditional polymers due to the their biodegradability, biocompatibility, and tenability in the body, and can be widely used in many biomedical fields, such as biosensors, nano medicine, tissue regeneration, and drug delivery.

The aim of this Special Issue is to discuss biomedical applications of silk-related materials, including their design, synthesis, characterization, and manufacturing or modeling, as well as their various physical and chemical applications in biological and medical fields. Research and review articles focusing on the above-mentioned fields are welcome.

Dr. Xiao Hu
Guest Editor

Manuscript Submission Information

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Keywords

  • silk
  • functional material (film, fiber, foam, gel, particle, sensor, device, composite)
  • tissue engineering and regenerative medicine
  • design, synthesis, characterization, manufacturing, modeling

Published Papers (4 papers)

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Research

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762 KiB  
Article
Characterization and Schwann Cell Seeding of up to 15.0 cm Long Spider Silk Nerve Conduits for Reconstruction of Peripheral Nerve Defects
by Tim Kornfeld, Peter M. Vogt, Vesna Bucan, Claas-Tido Peck, Kerstin Reimers and Christine Radtke
J. Funct. Biomater. 2016, 7(4), 30; https://doi.org/10.3390/jfb7040030 - 30 Nov 2016
Cited by 21 | Viewed by 9059
Abstract
Nerve reconstruction of extended nerve defect injuries still remains challenging with respect to therapeutic options. The gold standard in nerve surgery is the autologous nerve graft. Due to the limitation of adequate donor nerves, surgical alternatives are needed. Nerve grafts made out of [...] Read more.
Nerve reconstruction of extended nerve defect injuries still remains challenging with respect to therapeutic options. The gold standard in nerve surgery is the autologous nerve graft. Due to the limitation of adequate donor nerves, surgical alternatives are needed. Nerve grafts made out of either natural or artificial materials represent this alternative. Several biomaterials are being explored and preclinical and clinical applications are ongoing. Unfortunately, nerve conduits with successful enhancement of axonal regeneration for nerve defects measuring over 4.0 cm are sparse and no conduits are available for nerve defects extending to 10.0 cm. In this study, spider silk nerve conduits seeded with Schwann cells were investigated for in vitro regeneration on defects measuring 4.0 cm, 10.0 cm and 15.0 cm in length. Schwann cells (SCs) were isolated, cultured and purified. Cell purity was determined by immunofluorescence. Nerve grafts were constructed out of spider silk from Nephila edulis and decellularized ovine vessels. Finally, spider silk implants were seeded with purified Schwann cells. Cell attachment was observed within the first hour. After 7 and 21 days of culture, immunofluorescence for viability and determination of Schwann cell proliferation and migration throughout the conduits was performed. Analyses revealed that SCs maintained viable (>95%) throughout the conduits independent of construct length. SC proliferation on the spider silk was determined from day 7 to day 21 with a proliferation index of 49.42% arithmetically averaged over all conduits. This indicates that spider silk nerve conduits represent a favorable environment for SC attachment, proliferation and distribution over a distance of least 15.0 cm in vitro. Thus spider silk nerve implants are a highly adequate biomaterial for nerve reconstruction. Full article
(This article belongs to the Special Issue Silk Proteins for Biomedical Applications)
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3277 KiB  
Article
Consequences of Ultra-Violet Irradiation on the Mechanical Properties of Spider Silk
by Wee Loong Lai and Kheng Lim Goh
J. Funct. Biomater. 2015, 6(3), 901-916; https://doi.org/10.3390/jfb6030901 - 10 Sep 2015
Cited by 10 | Viewed by 7372
Abstract
The outstanding combination of high tensile strength and extensibility of spider silk is believed to contribute to the material’s toughness. Thus, there is great interest in engineering silk for biomedical products such as suture or implants. Additionally, over the years, many studies have [...] Read more.
The outstanding combination of high tensile strength and extensibility of spider silk is believed to contribute to the material’s toughness. Thus, there is great interest in engineering silk for biomedical products such as suture or implants. Additionally, over the years, many studies have also sought to enhance the mechanical properties of spider silk for wider applicability, e.g., by irradiating the material using ultra-violet radiation. However, the limitations surrounding the use of ultra-violet radiation for enhancing the mechanical properties of spider silk are not well-understood. Here, we have analyzed the mechanical properties of spider silk at short ultra-violet irradiation duration. Specimens of spider silk were subjected to ultra-violet irradiation (254-nm wavelength, i.e. UVC) for 10, 20, and 30 min, respectively, followed by tensile test to rupture to determine the strength (maximum stress), extensibility (rupture strain), and toughness (strain energy density to rupture). Controls, i.e., specimens that did not received UVC, were also subjected to tensile test to rupture to determine the respective mechanical properties. One-way analysis of variance reveals that these properties decrease significantly (p < 0.05) with increasing irradiation duration. Among the three mechanical parameters, the strength of the spider silk degrades most rapidly; the extensibility of the spider silk degrades the slowest. Overall, these changes correspond to the observed surface modifications as well as the bond rupture between the peptide chains of the treated silk. Altogether, this simple but comprehensive study provides some key insights into the dependence of the mechanical properties on ultra-violet irradiation duration. Full article
(This article belongs to the Special Issue Silk Proteins for Biomedical Applications)
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Review

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Review
Processing Techniques and Applications of Silk Hydrogels in Bioengineering
by Michael Floren, Claudio Migliaresi and Antonella Motta
J. Funct. Biomater. 2016, 7(3), 26; https://doi.org/10.3390/jfb7030026 - 14 Sep 2016
Cited by 84 | Viewed by 12156
Abstract
Hydrogels are an attractive class of tunable material platforms that, combined with their structural and functional likeness to biological environments, have a diversity of applications in bioengineering. Several polymers, natural and synthetic, can be used, the material selection being based on the required [...] Read more.
Hydrogels are an attractive class of tunable material platforms that, combined with their structural and functional likeness to biological environments, have a diversity of applications in bioengineering. Several polymers, natural and synthetic, can be used, the material selection being based on the required functional characteristics of the prepared hydrogels. Silk fibroin (SF) is an attractive natural polymer for its excellent processability, biocompatibility, controlled degradation, mechanical properties and tunable formats and a good candidate for the fabrication of hydrogels. Tremendous effort has been made to control the structural and functional characteristic of silk hydrogels, integrating novel biological features with advanced processing techniques, to develop the next generation of functional SF hydrogels. Here, we review the several processing methods developed to prepare advanced SF hydrogel formats, emphasizing a bottom-up approach beginning with critical structural characteristics of silk proteins and their behavior under specific gelation environments. Additionally, the preparation of SF hydrogel blends and other advanced formats will also be discussed. We conclude with a brief description of the attractive utility of SF hydrogels in relevant bioengineering applications. Full article
(This article belongs to the Special Issue Silk Proteins for Biomedical Applications)
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2117 KiB  
Review
Tissue Regeneration: A Silk Road
by Dave Jao, Xiaoyang Mou and Xiao Hu
J. Funct. Biomater. 2016, 7(3), 22; https://doi.org/10.3390/jfb7030022 - 05 Aug 2016
Cited by 81 | Viewed by 11108
Abstract
Silk proteins are natural biopolymers that have extensive structural possibilities for chemical and mechanical modifications to facilitate novel properties, functions, and applications in the biomedical field. The versatile processability of silk fibroins (SF) into different forms such as gels, films, foams, membranes, scaffolds, [...] Read more.
Silk proteins are natural biopolymers that have extensive structural possibilities for chemical and mechanical modifications to facilitate novel properties, functions, and applications in the biomedical field. The versatile processability of silk fibroins (SF) into different forms such as gels, films, foams, membranes, scaffolds, and nanofibers makes it appealing in a variety of applications that require mechanically superior, biocompatible, biodegradable, and functionalizable biomaterials. There is no doubt that nature is the world’s best biological engineer, with simple, exquisite but powerful designs that have inspired novel technologies. By understanding the surface interaction of silk materials with living cells, unique characteristics can be implemented through structural modifications, such as controllable wettability, high-strength adhesiveness, and reflectivity properties, suggesting its potential suitability for surgical, optical, and other biomedical applications. All of the interesting features of SF, such as tunable biodegradation, anti-bacterial properties, and mechanical properties combined with potential self-healing modifications, make it ideal for future tissue engineering applications. In this review, we first demonstrate the current understanding of the structures and mechanical properties of SF and the various functionalizations of SF matrices through chemical and physical manipulations. Then the diverse applications of SF architectures and scaffolds for different regenerative medicine will be discussed in detail, including their current applications in bone, eye, nerve, skin, tendon, ligament, and cartilage regeneration. Full article
(This article belongs to the Special Issue Silk Proteins for Biomedical Applications)
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