New Opportunities for an Ancient Material

Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA.
Science (Impact Factor: 33.61). 07/2010; 329(5991):528-31. DOI: 10.1126/science.1188936
Source: PubMed


Spiders and silkworms generate silk protein fibers that embody strength and beauty. Orb webs are fascinating feats of bioengineering in nature, displaying magnificent architectures while providing essential survival utility for spiders. The unusual combination of high strength and extensibility is a characteristic unavailable to date in synthetic materials yet is attained in nature with a relatively simple protein processed from water. This biological template suggests new directions to emulate in the pursuit of new high-performance, multifunctional materials generated with a green chemistry and processing approach. These bio-inspired and high-technology materials can lead to multifunctional material platforms that integrate with living systems for medical materials and a host of other applications.

1 Follower
15 Reads
  • Source
    • "Silk fibroin (SF), the main constituent of the natural silk, is a natural biopolymer and a fibrous protein produced by silkworms or spiders. SF is the strongest and toughest natural fiber, with unusual high tensile strength and elasticity and proved to be both biocompatible and biodegradable [2] [3] [4] [5] [6] [7] [8] [9] [10]. It is subject to prolonged biological proteolytic degradation into easily absorbed aminoacids and is very slowly resorbed in vivo (around one year or more) [3]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Composite silk fibroin–poly(3-hydroxybutyric-acid-co-3-hydroxyvaleric-acid) (SF–PHBV) biodegradable coatings were grown by Matrix Assisted Pulsed Laser Evaporation on titanium substrates. Their physico-chemical properties and particularly the degradation behavior in simulated body fluid at 37 • C were studied as first step of applicability in local controlled release for tissue regeneration applications. SF and PHBV, natural biopolymers with excellent biocompatibility, but different biodegradability and tensile strength properties, were combined in a composite to improve their properties as coatings for biomedical uses. FTIR analyses showed the stoichiometric transfer from targets to coatings by the presence in the spectra of the main absorption maxima characteristic of both polymers. XRD investigations confirmed the FTIR results showing differences in crystallization behavior with respect to the SF and PHBV content. Contact angle values obtained through wettability measurements indicated the MAPLE deposited coatings were highly hydrophilic; surfaces turning hydrophobic with the increase of the PHBV component. Degradation assays proved that higher PHBV contents resulted in enhanced resistance and a slower degradation rate of composite coatings in SBF. Distinct drug-release schemes could be obtained by adjusting the SF:PHBV ratio to controllably tuning the coatings degradation rate, from rapid-release formulas, where SF predominates, to prolonged sustained ones, for larger PHBV content.
    Applied Surface Science 11/2015; 355:1123-1131. DOI:10.1016/j.apsusc.2015.07.120 · 2.71 Impact Factor
    • "B. mori is a highly studied organism in life sciences due to its remarkably high level of protein synthesis during specific stages of its lifecycle. The unique properties of silk e strength and biocompatibility, mean it has attracted great interest as a biomaterial for tissue engineering, drug delivery and high technology interfaces (Altman et al., 2003; Omenetto and Kaplan, 2010). Aside from the biological interest, "
    [Show abstract] [Hide abstract]
    ABSTRACT: Silk is a protein of interest to both biological and industrial sciences. The silkworm, Bombyx mori, forms this protein into strong threads starting from soluble silk proteins using a number of biochemical and physical cues to allow the transition from liquid to fibrous silk. A pH gradient has been measured along the gland, but the methodology employed was not able to precisely determine the pH at specific regions of interest in the silk gland. Furthermore, the physiological mechanisms responsible for the generation of this pH gradient are unknown. In this study, concentric ion selective microelectrodes were used to determine the luminal pH of Bombyx mori silk glands. A gradient from pH 8.2 to 7.2 was measured in the posterior silk gland, with a pH 7 throughout the middle silk gland, and a gradient from pH 6.8 to 6.2 in the beginning of the anterior silk gland where silk processing into fibers occurs. The small diameter of the most anterior region of the anterior silk gland prevented microelectrode access in this region. Using a histochemical method, the presence of active carbonic anhydrase was identified in the funnel and anterior silk gland of fifth instar larvae. The observed pH gradient collapsed upon addition of the carbonic anhydrase inhibitor methazolamide, confirming an essential role for this enzyme in pH regulation in the Bombyx mori silk gland. Plastic embedding of whole silk glands allowed clear visualization of the morphology, including the identification of four distinct epithelial cell types in the gland and allowed correlations between silk gland morphology and silk stages of assembly related to the pH gradient. Bombyx mori silk glands have four different epithelial cell types, one of which produces carbonic anhydrase. Carbonic anhydrase is necessary for the mechanism that generates an intraluminal pH gradient, which likely regulates the assembly of silk proteins and then the formation of fibers from soluble silk proteins. These new insights into native silk formation may lead to a more efficient production of artificial or regenerated silkworm silk fibers.
    Insect biochemistry and molecular biology 09/2015; DOI:10.1016/j.ibmb.2015.09.001 · 3.45 Impact Factor
    • "Commercially, SF has been used for surgical sutures for decades and has biomedical applications because of its permeability to oxygen and water and protease susceptibility (Yan et al., 2010). The US Food and Drug Administration (FDA) has approved the use of SF for a few medical devices, such as blood vessels, peripheral nerve regeneration, femur defects and bone tissue engineering (Omenetto and Kaplan, 2010; Wang et al., 2008; Garcia-Fuentes et al., 2009). Hydroxyapatite (HaP) is a major mineral component of calcified tissues (bones and teeth). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Advances in tissue engineering have enabled the development of bioactive composite materials to generate biomimetic nanofibrous scaffolds for bone replacement therapies. Polymeric biocomposite nanofibrous scaffolds architecturally mimic the native extracellular matrix (ECM), delivering tremendous regenerative potential for bone tissue engineering. In the present study, biocompatible poly(l-lactic acid)-co-poly(ε-caprolactone)–silk fibroin–hydroxyapatite–hyaluronic acid (PLACL–SF–HaP–HA) nanofibrous scaffolds were fabricated by electrospinning to mimic the native ECM. The developed nanofibrous scaffolds were characterized in terms of fibre morphology, functional group, hydrophilicity and mechanical strength, using SEM, FTIR, contact angle and tabletop tensile-tester, respectively. The nanofibrous scaffolds showed a higher level of pore size and increased porosity of up to 95% for the exchange of nutrients and metabolic wastes. The fibre diameters obtained were in the range of around 255 ± 13.4–789 ± 22.41 nm. Osteoblasts cultured on PLACL–SF–HaP–HA showed a significantly (p < 0.001) higher level of proliferation (53%) and increased osteogenic differentiation and mineralization (63%) for the inclusion of bioactive molecules SF–HA. Energy-dispersive X-ray analysis (EDX) data proved that the presence of calcium and phosphorous in PLACL–SF–HaP–HA nanofibrous scaffolds was greater than in the other nanofibrous scaffolds with cultured osteoblasts. The obtained results for functionalized PLACL–SF–HaP–HA nanofibrous scaffolds proved them to be a potential biocomposite for bone tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.
    Journal of Tissue Engineering and Regenerative Medicine 09/2015; DOI:10.1002/term.2083 · 5.20 Impact Factor
Show more

Similar Publications


15 Reads
Available from