Advanced Materials Research Vol. 796

Abstract: Spider silks have excellent mechanical properties, which can even compare with some high-performance synthetic materials. Although as reported, the impressive mechanical properties are closely related to the primary amino acid sequence, the conformation that molecular chains form is also an important determinant. In this paper, effects of solvent, pH value, temperature, centrifugation and concentrating on the secondary structure of regenerated Ornithoctonus huwenna spider dragline silk protein aqueous solution were investigated by circular dichroism. Spidroin solutions prepared from different LiBr solutions had a distinct combination of secondary structures. The increasing temperature and concentrating can promote the formation of β-sheet structure. While centrifugation was opposite, which elevate the content of β-turn structure. Circular dichroic spectra quantitatively verified an increased α-helix structure content but a decrease of random coil and β-turn structure content with the increasing of pH value.

Abstract: The preparation and properties of different proportion of D-mannose-fibroin membrane were studied in this paper. The change of crystal structure of silk fibroin (SF) in the process of becoming insoluble by adding D-mannose was studied. The blend silk fibroin films were casted by silk fibroin solutions mixing with D-mannose at a series of ratios at room temperature. The solubility, structure, and mechanical properties of the blend films were measured. The results show that with the content of D-mannose increasing, the solubility decreases. The blend films became insoluble when the mass ratios of D-mannose /SF are more than 1/10. The crystalline structure of SF is mostly changed into Silk I and there was almost no Silk II structure. Mechanical properties indicated that D-mannose could significantly improve the flexibility of silk films. With the good transmittance, D-mannose/SF blend membrane can be used in corneal tissue engineering.

Abstract: A new method was developed to prepare the Antheraea Pernyi silk fibroin (ASF) microspheres and rhodamine was as a model drug. The structure of ASF microsphere carried drug was β-sheet structure characterized by X-ray diffraction and FTIR. The morphology of microspheres was observed by scanning electron microscope. The diameter of the ASF particles was not changed before and after drug carried. It was in the range of 1 μm to 5μm with a narrow size distribution. The encapsulation rate, drug content, and the drug release were tested. The resulted showed that encapsulation rate was increased and drug content was decreased with the addition of rhodamine increasing. The drug released 70% after 12 days and there was no significant difference with different pH value.

Abstract: Silk fibroin (SF) / pearl powder (PP) blend films with glycerol as a crosslinker were prepared by adding PP into SF solution and casting the SF solution onto the polystyrene disks at room temperature. The effects of amount of PP on surface morphology, structure, mechanical properties and water-solubility of films were investigated in this study. The surface morphology was observed with scanning electron microscope. The structure of films was investigated by X-ray diffraction. The dissolution rates of SF in films were measured by ultraviolet spectroscopy and mass loss percentages of the films were examined by weighing method. The elongation at break and the tensile strength of the films were measured on a universal testing machine. The results showed that surface of films without PP was smooth, particles rose increasingly obviously on the surface of films with PP with the increase of amount of PP. The condensed structure of SF in the films without PP was mainly silk I crystals. When the addition of PP was more than 5%, it had obvious effects on the crystal formation of SF in the films. Apart from silk I crystals, silk II crystals formed in the condensed structure of SF containing PP. The mass loss rate of films decreased with the increase of PP and the corresponding dissolution rate of SF was between 0.29% and 0.48% when the proportion of PP was in the range of 0% to 15%. The elongation at break was significantly affected by the addition of PP, but there were no significant effects on the tensile strength. When the proportion of PP was more than 5%, the elongation at break of the films dropped significantly.

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%.

Abstract: pH-sensitivity nanofibers composited of poly (vinyl alcohol) (PVA) and sodium carboxymethylcellulose (Na-CMC) were prepared by electrospining. The structure, properties, and morphology of the nanofibers were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray differential (XRD), scanning electron microscopy (SEM) and pH-sensitivity testing. It was found that the reswelling of the nanofibers was pH-responsive and relied on the content of Na-CMC. FTIR spectroscopy of the nanofibers confirmed that hydrogen bonds were formed between PVA and Na-CMC which may cause the stable increase of pH-sensitivity. XRD peaks gradually weakened and broadened with the increase of Na-CMC content, indicating the decrease of crystallinity_. Besides, the morphology of the PVA/ Na-CMC nanofibers was affected by the content of Na-CMC.

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: The magnetic flux density on the surface of magnetic fabric sample was measured by use the special instrument of high-precision Tesla measurement, and the distribution of the magnetic flux density on the surface of magnetic fabric was presented by the methods of information virtualization. The results of the measurement have showed that the values of the magnetic flux density on the surface of magnetic fabric sample, allowing negative value as well as positive value. The magnetic flux density on the surface of magnetic fabric has regional and inhomogeneity of the distribution. The experiment has been conducted on washing and chafing to research the varying characteristics of the magnetic flux density on the surface of magnetic fabric sample. The results of the experiments shows that the magnetic flux density on the surface of magnetic fabric trends to increase firstly in the beginning of washing experiment and then decrease after three times of washing. Generally, fabric loses magnetic after washing 15 times or so. One of the key factors influencing the durability of the magnetic flux density on the surface of magnetic fabric is the content of magnetic fiber in magnetic fabric.

Abstract: The content of magnetic fiber is the determinate element of both the surface magnetic field intensity and the economic cost of the magnetic fabric. It probably has certain influence on fabric wearability. In this study, experimental method has been adopted to investigate the wearability of knitted magnetic fabric which is woven of magnetic fiber and non-magnetic fiber in different proportions. The mechanical property, pilling resistance, moisture permeability and other properties of magnetic fiber have been tested. The results of study shows that as magnetic fiber content in the magnetic fabric increases, the breaking strength, bursting strength and pilling resistance of the fabric decrease and the moisture permeability variation. But the bending property, drapability and dimension stability of the fabric nearly have no evident relation with the content of magnetic fiber. This study can provide references for the further research of the magnetic health-care garment and will make the magnetic fabric better uses on garment.

Abstract: The researchers of liquid detergent are most focused on detergency in the past, and the research on antibacterial activity of liquid detergent is rare. This research choose famous and common brands liquid laundry detergent in the market and studied their antimicrobial properties, test their antibacterial properties on the surface of the natural fiber fabric about Staphylococcus aureus (positive) and Escherichia coli (negative), analysis the antibacterial effect of the various brands, and the consumers have more reliable basis for purchase such goods. The antibacterial rate of liquid detergent against Galanz negative bacteria (E. coli) is generally higher, but the antibacterial rate against Galanz positive bacteria (S.aureus) is not good. The brand of Lan Yue Liang has excellent performance in this experiment, the antibacterial rate against E. coli and S.aureus reached to 96.25% and 95%.