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Graphene (Gr) has been made of various forms used for repairing peripheral nerve injury with favorable electroactivity, however, graphene-based scaffolds in peripheral nerve regeneration are still rarely reported due to the difficulty of realizing uniform dispersion of graphene and electroactive materials at nanoscale as well as lacking biocompatibility. In this paper, graphene-silk fibroin (SF) composite nanofiber membranes with different mass ratios were prepared via electrospinning. Microscopic observation revealed that electrospun Gr/SF membranes had a nanofibrous structure. Electrochemical analysis provided electroactivity characterization of the Gr/SF membranes. The physiochemical results showed that the physiochemical properties of electrospun Gr/SF membranes could be changed by varying Gr concentration. Swelling ratio and contact angle measurements confirmed that electrospun Gr/SF membranes possessed large absorption capacity and hydrophilic surface, and the mechanical property was improved with increasing Gr concentration. Additionally, in-vitro cytotoxicity with L929 revealed that all the electrospun Gr/SF membranes are biocompatible. Moreover, the morphology and quantity showed that the membranes supported the survival and growth of the cultured Schwann cells. Collectively, all of the results suggest that the electrospun Gr/SF membranes combine the excellent electrically conductivity and mechanical strength of the graphene with biocompatibility property of silk to mimic the natural neural cell micro-environment for nerve development.

Various hydrogels made from natural or synthetic polymers have been widely used in biologic tissues, drug delivery, and artificial implants due to their good biocompatibility, indicating a promising perspective in regenerative medicine. In the present study, a composite hydrogel named polyacrylamide/graphene oxide/gelatin/sodium alginate (PAM/GO/Gel/SA) for accelerating peripheral nerve regeneration was fabricated through in situ free radical polymerization for the first time. A series of physicochemical properties including morphology, porosity, swelling behaviors, component, mechanical properties, and in vitro degradation behavior of the prepared composite hydrogel were characterized. The effects of the composite hydrogel on Schwann cells growth were evaluated and the related molecular mechanism was further penetrated. The results showed that the prepared PAM/GO/Gel/SA composite hydrogels displayed different color appearance as the function of component variations. The surface morphology, components, swelling ratio, mechanical properties, and porosity were all changed with the concentration alteration of each ingredient, while no obvious degradation behavior was observed, indicating a controllable physicochemical property. The culture of cells exhibited that the composite hydrogels could well support the attachment and proliferation of Schwann cells. The gene expression levels of Sox10, GAP43, and myelin basic protein (MBP) in PGG SYR1 and PGG SYR0.5 were higher than those of NC. This study may provide important theoretical and experimental basis for the design and development of hydrogel scaffolds for nerve tissue engineering application. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1951-1964, 2018.

Bioprinting has exhibited remarkable promises for the fabrication of functional skin substitutes. However, there are some significant challenges for the treatment of full-thickness skin defects in clinical practice. It is necessary to determine bioinks with suitable mechanical properties and desirable biocompatibilities. Additionally, the key for printing skin is to design the skin structure optimally, enabling the function of the skin. In this study, the full-thickness skin scaffolds were prepared with a gradient pore structure constructing the dense layer, epidermis, and dermis by different ratios of bioinks. We hypothesized that the dense layer protects the wound surface and maintains a moist environment on the wound surface. By developing a suitable hydrogel bioink formulation (sodium alginate/gelatin/collagen), to simulate the physiological structure of the skin via 3D printing, the proportion of hydrogels was optimized corresponding to each layer. These results reveal that the scaffold has interconnected macroscopic channels, and sodium alginate/gelatin/collagen scaffolds accelerated wound healing, reduced skin wound contraction, and re-epithelialization in vivo. It is expected to provide a rapid and economical production method of skin scaffolds for future clinical applications.

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