Papers by Keyword: Silk Fibroin

Abstract: This study was focused on the preparation of electrospunnanofibres from silk fibroin (SF)/gelatin (GP) blends solution using a roller electro spinning method. The effects of mixing ratio in SF/GP blend solution on properties of spinning solution (e.g., viscosity, conductivity and surface tension) and morphology of electrospunfibres were studied. The SF/GP blends solution containing up to the gelatin content of 30% could be electro spun into the continuous fibrous structure. Average diameter of SF/GP electrospunfibres were increased by increasing the amount of gelatin in spinning solution. The SF/GP electrospunfibres showed bigger diameter and broader diameter distribution than pure silk fibroin electrospunfibres. The SF/GP nanofibres had diameters ranging from 400 to 1300 nm.

Abstract: In this study, bilayered silk and silk/nanoCaP scaffolds were developed for osteochondral tissue engineering. Aqueous silk solution (16 wt.%) was used for preparation of the cartilage-like layer and, for generation of the silk/nanoCaP suspension and the bottom layer (CaP/Silk: 16 wt.%). The scaffolds were formed by using salt-leaching/lyophilization approach. The scanning electron microscopy revealed that the both layers presented porous structure and integrated well. Micro-computed tomography images confirmed that the CaP phase was only retained in the silk/nanoCaP layer. The hydration degree and mechanical properties of the bilayered scaffold were comparable to the ones of each single layer. The apatite crystal formation was limited to the silk/nanoCaP layer, when soaking the scaffold in a simulated body fluid solution, which is a must for the application of the developed scaffolds in OC tissue engineering.

Abstract: Hydroxyapatite (HA) has been widely utilized in the biomedical applications due to its chemical and structural features that are similar to the natural bones. The addition of organic components enhances the flexibility of the HA-based composites which result in increasing its molding ability into any desirable shapes. In this article, preparation of hydroxyapaptite/silk fibroin (HA/SF) composite using sol-gel method is reported. The optimal condition for preparing the HA/SF composites was determined by judging from their crystallite size, crystallinity and particle size distribution, morphology and calcium/phosphorus (Ca/P) ratio investigated with X-ray diffraction analysis, particle size analyzer, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. The HA/SF composite was successfully prepared in the binary solvent of ethanol and water at the optimal volume ratio of 4:1. At this solvent condition, the composites had a uniform rod-liked shape, ranging from 30-70 nanometers. The Ca/P ratios of all composites are close to the theoretical value of about 1.67.

Abstract: Silk fibroin (SF) and rice starch (RS) are both biopolymers being non-toxic, biocompatible and biodegradable which can be utilized as hydrogels. The aim of this study was to prepare the SF–RS hydrogels modified with trisodium trimetaphosphate (STMP) and determine its crosslinking density for providing a guideline for preparing better quality absorbable hydrogels. The SF–RS hydrogels modified with various percentages of STMP were prepared by solution casting at pH 12 then neutralized to pH 7. The functional groups and molecular linkages of the hydrogels were investigated by Fourier transform infrared spectrometry (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectrometry, respectively. Finally, the crosslinking density of the hydrogels was determined by UV/Vis spectrophotometry via the measurement of the relative amount of methylene blue (RMB) bound to the hydrogels. Results from the FTIR and ¹H NMR spectra revealed that linkages within the hydrogels occurred mainly between the O–H groups of RS and the triphosphate groups of STMP. From the MB adsorption study, the crosslinking density of the SF–RS hydrogel with 1.0 %w/w STMP at the 60 min saturation time was approximately 63 %.

Abstract: Eco-friendly films have been prepared using various biopolymers and their properties have been improved in order to meet the requirements for appropriate applications. However, the frequently encountered weakness of the properties of most biopolymer film is its water solubility. In this study, the polyvinyl alcohol/rice starch/silk fibroin (PVA/RS/SF) films were modified by the addition of glycerol aiming to increase the hydrophobicity of the films. Some properties of the modified films including water contact angle, degree of swelling and water solubility were compared with the unmodified PVA/RS/SF film. Results from the contact angle measurement showed that the films with glycerol could be transformed to be hydrophobic after soaking in ethanol medium. The increase in soaking time tends to increase the hydrophobicity of the films. However, at about 60 min soaking, the water contact angles on the films were quite constant with the values of about 107.9±5.2º comparing with 65.3±2.4º of the ethanol-untreated PVA/RS/SF films. In addition, the ethanol-treated glycerol-modified films also show higher degree of swelling with constant solubility and better mechanical properties.

Abstract: Three-dimensional (3D) mesoporous bioactive glass (MBG) scaffolds were obtained by using the demineralized bone matrix (DBM) and P123 as co-templates through a dip-coating method followed by evaporation induced self-assembly (EISA) process. 3D mesoporous bioactive glass-silk fibroin (MBG/SF) composite scaffolds were prepared by immersing MBG scaffolds into SF solutions with different concentration. Transmission electron microscopy (TEM), field mission scanning electron microscope (FESEM), fourier transform infrared spectroscopy (FT-IR) and wide angle X-ray diffraction (WA-XRD) were used to analyze the inner pore structures, pore sizes, morphologies and composition of the scaffolds. The in vitro bioactivity of the scaffolds was evaluated by soaking in simulated body fluid (SBF). The results showed that the MBG and MBG/SF composite scaffolds with the interconnected macroporous network and mesoporous walls could be obtained by this method. In addition, both the MBG scaffolds and the MBG/SF composite scaffolds have excellent apatite-forming bioactivity. Therefore, this method provides a simple way to prepare scaffolds for bone tissue engineering.

Abstract: Objective: To explore the effects of the biodegradability of biomaterial scaffolds on skin tissue regeneration and its neovascularization by the animal experiments. Methods: A piece of porous silk fibroin film (SF) of easy biodegradation and a piece of porous polyvinyl alcohol film (PVA) of hard biodegradation were implanted into a same skin wound of adult rat, and the differences in the regenerative blood vessel and tissue at 5, 10, 16, 41 days after surgery were observed by histological methods. Results: (1) at 10 days after surgery, the SF started to degrade, the closed areas without cell infiltration were opened up and the entire material was filled with the regenerative tissue, and there were still the closed areas in the PVA, (2) the new vascular network remodeling in the SF and PVA appeared at 10 days and 41 days after surgery, respectively, and (3) at 16 days after surgery, most of the SF material had degraded and substantially been replaced with the regenerative tissue, and the visible degradation of the PVA appeared at 41 days after surgery. Conclusion: The good biodegradability of the SF was helpful both to all vascularization of the material and to the regenerative blood vessels remodeling, and the regenerative tissue was closer to the normal dermal tissue than in the PVA.

Abstract: Silk fibroin (SF) has good biocompatibility and has been used to construct small caliber artificial blood vessels. As a vascular graft, the antithrombogenicity is the first important performance. The aim of this study was to evaluate the anticoagulant property of polyethylene glycol diglycidyl ether (PEG-DE) crosslinked and ethanol treated SF materials by investigating the platelet adhesion. Dacron and PTFE were parallel studied as the controls. Results showed that: the platelet adhesion ratios on the ethanol treated SF films were significantly lower than that on the Dacron and PTFE; the platelet adhesion ratios on the PEG-DE crosslinked SF films were higher than that on the ethanol treated SF films and slightly increased with increasing the proportion of the PEG-DE. But the platelet adhesion ratios on all of the PEG-DE crosslinked SF films were significantly lower than that on the controls.

Abstract: A block combination genes (gx16-f) was designed and cloned for encoding GX16-F, which was derived from the crystalline domain (X: A, S, V or Y, GA: GAGAGA, GS: GAGAGS, GV: GAGAGV and GY: GAGAGY) and the amorphous domain (F=SGFGPVANGGSGEASSESDFGSSGFGPVANASSGEASSESDFAG) of Bombyx mori silk fibroin heavy chain. The combination genes were then cloned into a GST-tagged prokaryotic expression vector for expression of protein. Agarose gel electrophoresis analysis and DNA sequencing demonstrated that the combination gene encoding GX16-F was accurately cloned, and inserted into the expression vector successfully. The study would provide a technology to produce different structural polypeptides for studying the structurefunction relationships of silk fibroin.

Abstract: In the present study, glycerol was used as plasticizer to prepare silk fibroin (SF)/pearl powder (PP) blend films. The effects of amount of glycerol on structure and properties of the films were investigated. The surface morphology was observed with scanning electron microscopy. The structure of films was investigated by X-ray diffraction and thermal analysis. The mechanical properties of the films were measured on a universal testing machine, and the dissolution rate of SF was examined by ultraviolet spectroscopy. The results showed that surface of pure SF films was smooth, but the surface of films containingPP was uneven, particles of PP dispersed in the films. The structure of the film without glycerol was mainly amorphous structure. The structure of the SF in the film was mainly silk I and silk II when the proportion of glycerol added was in the range of 10%- 20%, while the main structure of the SF in the films was silk I when the proportion of glycerol was more than 20%. The dissolution rate of SF in films without glycerol is rather great, while the dissolution rate had a significant decrease by adding glycerol. There was no significant difference in dissolution rates of SF which were all below 1.3% when the proportion of glycerol is 10-40%. The films without glycerol had very small elongation at break. The elongation at break of SF films increased with the increased amount of glycerol. Compared to films without glycerol, there was a significant difference when the proportion of glycerol was greater than 10%. The tensile strength of the films dropped significantly with the increase of glycerol, but there was no significant difference when the proportion of glycerol was greater than 30%. Therefore, the advisable addition percentage of glycerol is 20%.