Designing hydrogels with high mechanical properties without sacrificing their self-healing efficiencies remains great challenges. We have fabricated cationic polyacrylamide/graphene oxide (GO) hydrogels by free-radical polymerization of acrylamide (AM) and 2-(dimethylamino)ethylacrylatemethochloride (DAC) in the presence of GO. The mechanical properties and self-healing ability can be tuned by the GO content and the mass ratio of AM and DAC. The ionic bonds between DAC and GO and the hydrogen bonds between AM and GO can efficiently dissipate energy and rebuild the networks. The resulting composite hydrogels possess high stiffness (Young's modulus: ∼1.1 MPa), high toughness (∼9.3 MJ m-3), and high fatigue resistance, as well as high self-healing efficiency (>92% of tensile strength, >99% of tensile strain and >93% of toughness). In addition, the completely dried hydrogels can recover their original mechanical values by spraying water and still possess outstanding self-healing efficiency. Our design can provide better fundamental understanding of physical properties of hydrogels and should enable the development of tough, self-healing hydrogels for practical applications.
The goal of this study was to fabricate Antheraea pernyi silk fibroin (ASF) microparticles using electrospinning under mild processing conditions. To improve processability of the ASF solution, poly(ethylene oxide) (PEO) was used to regulate viscosity of ASF solution for electrospinning. It was found that the blend of ASF with PEO could form a bead-on-string structure with well spherical particles. Furthermore, aqueous ethanol and ultrasonic treatments could disrupt the nanofibrillar string structure between particles and ultimately produced water-insoluble ASF particles with submicron scale. Cell viability studies indicated that the ASF microparticles were nontoxic to EA926 cells. Moreover, fluorescent images based on FITC labeling showed that the ASF microparticles were easily uptaken by the cells. Aqueous-based electrospinning provides a potentially useful option for the fabrication of ASF microparticles based on this unique fibrous protein.
The circadian clock plays a critical role in the regulation of host immune defense. However, the mechanistic basis for this regulation is largely unknown. Herein, the core clock gene cryptochrome1 (cry1) knockout line in Bombyx mori, an invertebrate animal model, was constructed to obtain the silkworm with dysfunctional molecular clock, and the dynamic regulation of the circadian clock on the immune responsiveness within 24 h of Staphylococcus aureus infection was analyzed. We found that deletion of cry1 decreased viability of silkworms and significantly reduced resistance of larvae to S. aureus. Time series RNA-seq analysis identified thousands of rhythmically expressed genes, including immune response genes, in the larval immune tissue, fat bodies. Uninfected cry1 knockout silkworms exhibited expression patterns of rhythmically expressed genes similar to wild-type (WT) silkworms infected with S. aureus. However, cry1 knockout silkworms exhibited a seriously weakened response to S. aureus infection. The immune response peaked at 6 and 24 h after infection, during which "transcription storms" occurred, and the expression levels of the immune response genes, PGRP and antimicrobial peptides (AMPs), were significantly upregulated in WT. In contrast, cry1 knockout did not effectively activate Toll, Imd, or NF-κB signaling pathways during the immune adjustment period from 12 to 18 h after infection, resulting in failure to initiate the immune responsiveness peak at 24 h after infection. This may be related to inhibited silkworm fat body energy metabolism. These results demonstrated the dynamic regulation of circadian clock on silkworm immune response to bacterial infection and provided important insights into host antimicrobial defense mechanisms.
Complete amino acid sequences of the four major proteins (Vssilk 1−4) of silk (hornet silk) obtained from yellow hornet (Vespa simillima, Vespinae, Vespidae) cocoons have been determined. The native structure of the hornet silk (HS), in which Vssilk 1−4 have an α-helix domain with coiled-coil α-helices and a β-sheet domain, is restored when hornet silk gel films (HSGFs) are formed by pressing and drying HS hydrogel. Necking occurs when dry HSGFs are drawn; however, wet HSGFs can be uniaxially drawn with a draw ratio (DR) of 2. Drawing helps obtain high-performance films with a maximum tensile strength and tensile modulus of 170 MPa and 5.5 GPa, respectively. Drawing-induced changes in the orientation and conformation of the coiled-coil structure are investigated.
The inclusion complex formation of irisquinone with hydroxypropyl-beta-cyclodextrin(HP-beta-CD) and the physico- chemical properties were studied. Complex of host molecules with irisquinoe was studied by x-ray diffraction (XRD) and differential scanning calorimetry(DSC). The quantitative analysis with uv-vis indicated that HP-beta-CD could increase the solubility of irisquinone, where the best results was given with HP-beta-CD :irisquinone 2:1 molar ratio. The binding constants of inclusion complex formulation were obtained with relative Higuchi Principle and thermodynamics equation.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)