In Vivo Biological Responses to Silk Proteins Functionalized with Bone Sialoprotein

Recombinant 6mer + BSP protein, combining six repeats of the consensus sequence for Nephila clavipes dragline (6mer) and bone sialoprotein sequence (BSP), shows good support for cell viability and induces the nucleation of hydroxyapatite and tricalcium phosphate during osteoblast in vitro culture. The present study is conducted to characterize this bioengineered protein‐based biomaterial further for in vivo behavior related to biocompatibility. 6mer + BSP protein films are implanted in subcutaneous pouches in the back of mice and responses are evaluated by flow cytometry and histology. The results show no major differences between the inflammatory responses induced by 6mer + BSP films and the responses observed for the controls. Thus, this new chimeric protein could represent an alternative for bone regeneration applications.

     

Comparative Study of Silk Fibroin-Based Hydrogels and Their Potential as Material for 3-Dimensional (3D) Printing

Three-dimensional (3D) printing is regarded as a critical technology in material engineering for biomedical applications. From a previous report, silk fibroin (SF) has been used as a biomaterial for tissue engineering due to its biocompatibility, biodegradability, non-toxicity and robust mechanical properties which provide a potential as material for 3D-printing. In this study, SF-based hydrogels with different formulations and SF concentrations (1–3%wt) were prepared by natural gelation (SF/self-gelled), sodium tetradecyl sulfate-induced (SF/STS) and dimyristoyl glycerophosphorylglycerol-induced (SF/DMPG). From the results, 2%wt SF-based (2SF) hydrogels showed suitable properties for extrusion, such as storage modulus, shear-thinning behavior and degree of structure recovery. The 4-layer box structure of all 2SF-based hydrogel formulations could be printed without structural collapse. In addition, the mechanical stability of printed structures after three-step post-treatment was investigated. The printed structure of 2SF/STS and 2SF/DMPG hydrogels exhibited high stability with high degree of structure recovery as 70.4% and 53.7%, respectively, compared to 2SF/self-gelled construct as 38.9%. The 2SF/STS and 2SF/DMPG hydrogels showed a great potential to use as material for 3D-printing due to its rheological properties, printability and structure stability.     

3D Printing of Silk Protein Structures by Aqueous Solvent‐Directed Molecular Assembly

Hierarchical molecular assembly is a fundamental strategy for manufacturing protein structures in nature. However, to translate this natural strategy into advanced digital manufacturing like three‐dimensional (3D) printing remains a technical challenge. This work presents a 3D printing technique with silk fibroin to address this challenge, by rationally designing an aqueous salt bath capable of directing the hierarchical assembly of the protein molecules. This technique, conducted under aqueous and ambient conditions, results in 3D proteinaceous architectures characterized by intrinsic biocompatibility/biodegradability and robust mechanical features. The versatility of this method is shown in a diversity of 3D shapes and a range of functional components integrated into the 3D prints. The manufacturing capability is exemplified by the single‐step construction of perfusable microfluidic chips which eliminates the use of supporting or sacrificial materials. The 3D shaping capability of the protein material can benefit a multitude of biomedical devices, from drug delivery to surgical implants to tissue scaffolds. This work also provides insights into the recapitulation of solvent‐directed hierarchical molecular assembly for artificial manufacturing.     

激光单丝衍射附加条纹的探讨

本文报道了激光单丝衍射的附加条纹现象，并对其形成机理进行了探讨，提出了两种模型。     

Metal Oxide Nanomaterials with Nitrogen‐Doped Graphene‐Silk Nanofiber Complexes as Templates

Fabricating electrode materials with superior electrochemical performance remains a challenge. Here, a simple but effective strategy for the formation of metal oxide nanomaterials with superior performance has been developed. Silk protein nanofibers adhered on reduced graphene oxide (rGO) sheets are used as templates to regulate the formation of nanostructured iron oxide composites, achieving porous nanorod structures that could not be attained in control experiments. These porous nanorods demonstrate superior electrochemical performance as electrodes with retention of a capacity of 1495 mAh g^?1 after 180 cycles at 0.2 C and a rate capability of 900 mAh g^?1 at 2 C discharge rate. These new rGO/silk composite templates provide a more controllable environment for Fe₂O₃ fabrication, resulting in improved nanostructures and superior electrical performance. The strategy developed here should also be more broadly applicable in the design of metal oxide nanomaterials with specialized structures and useful performance.     

Porous 3‐D scaffolds from regenerated Antheraea pernyi silk fibroin

In this study, porous three‐dimensional (3‐D) materials were prepared with the regenerated Antheraea pernyi (A. pernyi) silk fibroin by freeze‐drying from a lithium thiocyanate solution of its fibers. The relationship between preparation conditions and morphological structures of 3‐D materials was also studied. We concluded that with the decrease in A. pernyi silk fibroin solution concentration and the increase in the freezing temperature, the porosity and the average pore diameter of the 3‐D materials were increased while the pore density was decreased. By adjusting the freezing temperature and the silk fibroin solution concentration, the 3‐D materials having the average pore diameter of 75–260 µm and the porosity of 70–90% can efficiently be produced. As a kind of new material with excellent biocompatibility and bioactivity, the material is expected to be applied to tissue regeneration scaffolds. Copyright © 2007 John Wiley & Sons, Ltd.     

Thermal properties and phase transitions in blends of Nylon-6 with silk fibroin

The thermal and structural properties of binary blends of Nylon-6 (N6) and a chemically related biopolymer, Bombyx mori silk fibroin (SF), are reported in this work. Homopolymers and blends, in composition ratios of N6/SF ranging from 95/05 to 70/30, were investigated by thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and wide angle X-ray scattering (WAXS). Silk fibroin typically degrades at temperatures just above 210°C, which occurs within the melting endotherm of N6. In TG studies, the measured mass remaining was slightly greater than expected, indicating the blends had improved thermal stability. No beta sheet crystals of SF were detected by FTIR analysis of the Amide I region. Strong interaction between N6 and SF chains was observed, possibly as a result of formation of hydrogen bonds between N6 and SF chains. DSC analysis showed that the addition of SF to N6 caused a decrease in the crystallization temperature, the melting temperature of the lowest melting crystals and the crystallinity of N6. Furthermore, the α-crystallographic phase dominates and the γ-crystallographic phase was not observed in N6/SF blends, in contrast to the homopolymer N6, which contains both phases. We suggest that the addition of SF might result in changes of the chain extension of N6, which lead to the appearance of α-rather than γ-phase crystals.