Tyrosine residues mediate supercontraction in biomimetic spider silk

Water and humidity severely affect the material properties of spider major ampullate silk, causing the fiber to become plasticized, contract, swell and undergo torsion. Several amino acid residue types have been proposed to be involved in this process, but the complex composition of the native fiber complicates detailed investigations. Here, we observe supercontraction in biomimetically produced artificial spider silk fibers composed of defined proteins. We found experimental evidence that proline is not the sole residue responsible for supercontraction and that tyrosine residues in the amorphous regions of the silk fiber play an important role. Furthermore, we show that the response of artificial silk fibers to humidity can be tuned, which is important for the development of materials for applications in wet environments, eg producing water resistant fibers with maximal strain at break and toughness modulus.

3D Silk Fiber Construct Embedded Dual-Layer PEG Hydrogel for Articular Cartilage Repair – In vitro Assessment

Since articular cartilage does not regenerate itself, researches are underway to heal damaged articular cartilage by applying biomaterials such as a hydrogel. In this study, we have constructed a dual-layer composite hydrogel mimicking the layered structure of articular cartilage. The top layer consists of a high-density PEG hydrogel prepared with 8-arm PEG and PEG diacrylate using thiol-norbornene photo-click chemistry. The compressive modulus of the top layer was 700.1 kPa. The bottom layer consists of a low-density PEG hydrogel reinforced with a 3D silk fiber construct. The low-density PEG hydrogel was prepared with 4-arm PEG using the same cross-linking chemistry, and the compressive modulus was 13.2 kPa. Silk fiber was chosen based on the strong interfacial bonding with the low-density PEG hydrogel. The 3D silk fiber construct was fabricated by moving the silk fiber around the piles using a pile frame, and the compressive modulus of the 3D silk fiber construct was 567 kPa. The two layers were joined through a covalent bond which endowed sufficient stability against repeated torsions. The final 3D silk fiber construct embedded dual-layer PEG hydrogel had a compressive modulus of 744 kPa. Chondrogenic markers confirmed the chondrogenic differentiation of human mesenchymal stem cells encapsulated in the bottom layer.

Application of Nano Sericin Finish on Polyester Fabric

Textiles of today are materials with applications in almost all our activities, Silk is a natural protein fiber used by mankind for more centuries. The silk fiber mainly contains two types of proteins they are fibroin and sericin. The sticky protein sericin is removed in the degumming process and discarded as wastewater in silk fiber production industry. In this study, the wastewater sericin is collected from the industry and recovered the sericin by various extraction methods. Then convert into nano sericin particles and the nanosericin is applied to the polyester fabric to improve the absorbency property of the fabric.