Liquid-phase exfoliation （LPE） is an attractive method for the scaling-up of exfoliated MoS2 sheets compared to chemical vapor deposition and mechanical cleavage. However, the MoS2 nanosheet yield from LPE is too sm...Liquid-phase exfoliation （LPE） is an attractive method for the scaling-up of exfoliated MoS2 sheets compared to chemical vapor deposition and mechanical cleavage. However, the MoS2 nanosheet yield from LPE is too small for practical applications. We report a facile method for the scaling-up of exfoliated MoS2 nanosheets using freeze-dried silk fibroin powders. Compared to MoS2 dispersion in the absence of silk fibroin powder, sonicated MoS2 dispersions with silk fibroin powder （MoSJSilk dispersion） show noticeably higher exfoliated MoS2 nanosheet yields, with suspended MoS2 concentrations in MoS2/Silk dispersions sonicated for 2 and 5 h of 1.03 and 1.39 mg.mL-1, respectively. The MoS2 concentration in the MoS2/Silk dispersion after centrifugation above 10,000 rpm is more than four times that without the silk fibroin. The size of the dispersed silk fibroin is controlled by the change of centrifugation rate, showing the removal of silk fibroin above tens of micrometers in size after centrifugation at 2,000 rpm. Size-controlled silk fibroin biomolecules combined with MoS2 nanosheets are expected to increase the practical use of such materials in fields related to tissue engineering, biosensors and electrochemical electrodes. Atomic force microscopy and Raman spectroscopy provide the height of the MoS2 nanosheets spin-cast from MoS2/Silk dispersions, showing thicknesses of 3--6 nm. X-ray photoelectron spectroscopy and X-ray diffraction indicate that the outermost surface layer of the hydrophobic MoS2 crystals interact with oxygen-containing functional groups that exist in the hydrophobic part of silk fibroins. The amphiphilic properties of silk fibroin combined with the MoS2 nanosheets stabilize dispersions by enhancing solvent-material interactions. The large quantities of exfoliated MoS2 nanosheets suspended in the as-synthesized dispersions can be utilized for the fabrication of vapor and electrochemical devices requiring high MoS2 nanosheets contents.展开更多
In this study, a novel polyurethane membrane, modified by superfine silk-fibroin powder, was prepared for small-diameter vascular grafting. Scanning electron microscopy, transmission electron microscopy, and histologi...In this study, a novel polyurethane membrane, modified by superfine silk-fibroin powder, was prepared for small-diameter vascular grafting. Scanning electron microscopy, transmission electron microscopy, and histological examination were applied to evaluate histocompatibility of this polyurethane membrane. The polyurethane membrane was compared with polytetrafluoroethylene material. A pseudomembrane and gap formed between polytetrafluoroethylene and the surrounding tissues, and no cells infiltrated or grew into the polytetrafluoroethylene material. On the contrary, superfine silk-fibroin powder/polyurethane blend membrane merged tightly with the surrounding tissues without gaps, and cells infiltrated and grew into the material. Moreover, the negative effects of superfine silk-fibroin powder/polyurethane blend membrane on cells were less than those of its polytetrafluoroethylene counterpart. Our findings indicated that the superfine silk-fibroin powder/polyurethane blend membrane has better histocompatibility than polytetrafluoroethylene membrane. It is concluded that the superfine silk-fibroin powder/polyurethane blend membrane is a promising biomaterial for small-diameter prosthesis.展开更多
文摘Liquid-phase exfoliation （LPE） is an attractive method for the scaling-up of exfoliated MoS2 sheets compared to chemical vapor deposition and mechanical cleavage. However, the MoS2 nanosheet yield from LPE is too small for practical applications. We report a facile method for the scaling-up of exfoliated MoS2 nanosheets using freeze-dried silk fibroin powders. Compared to MoS2 dispersion in the absence of silk fibroin powder, sonicated MoS2 dispersions with silk fibroin powder （MoSJSilk dispersion） show noticeably higher exfoliated MoS2 nanosheet yields, with suspended MoS2 concentrations in MoS2/Silk dispersions sonicated for 2 and 5 h of 1.03 and 1.39 mg.mL-1, respectively. The MoS2 concentration in the MoS2/Silk dispersion after centrifugation above 10,000 rpm is more than four times that without the silk fibroin. The size of the dispersed silk fibroin is controlled by the change of centrifugation rate, showing the removal of silk fibroin above tens of micrometers in size after centrifugation at 2,000 rpm. Size-controlled silk fibroin biomolecules combined with MoS2 nanosheets are expected to increase the practical use of such materials in fields related to tissue engineering, biosensors and electrochemical electrodes. Atomic force microscopy and Raman spectroscopy provide the height of the MoS2 nanosheets spin-cast from MoS2/Silk dispersions, showing thicknesses of 3--6 nm. X-ray photoelectron spectroscopy and X-ray diffraction indicate that the outermost surface layer of the hydrophobic MoS2 crystals interact with oxygen-containing functional groups that exist in the hydrophobic part of silk fibroins. The amphiphilic properties of silk fibroin combined with the MoS2 nanosheets stabilize dispersions by enhancing solvent-material interactions. The large quantities of exfoliated MoS2 nanosheets suspended in the as-synthesized dispersions can be utilized for the fabrication of vapor and electrochemical devices requiring high MoS2 nanosheets contents.
基金supported by a grant from the 973 Programof Ministry of Science and Technology of China(No.2009CB526400)
文摘In this study, a novel polyurethane membrane, modified by superfine silk-fibroin powder, was prepared for small-diameter vascular grafting. Scanning electron microscopy, transmission electron microscopy, and histological examination were applied to evaluate histocompatibility of this polyurethane membrane. The polyurethane membrane was compared with polytetrafluoroethylene material. A pseudomembrane and gap formed between polytetrafluoroethylene and the surrounding tissues, and no cells infiltrated or grew into the polytetrafluoroethylene material. On the contrary, superfine silk-fibroin powder/polyurethane blend membrane merged tightly with the surrounding tissues without gaps, and cells infiltrated and grew into the material. Moreover, the negative effects of superfine silk-fibroin powder/polyurethane blend membrane on cells were less than those of its polytetrafluoroethylene counterpart. Our findings indicated that the superfine silk-fibroin powder/polyurethane blend membrane has better histocompatibility than polytetrafluoroethylene membrane. It is concluded that the superfine silk-fibroin powder/polyurethane blend membrane is a promising biomaterial for small-diameter prosthesis.
