Direct ink writing of graphene-based composites : from inks to flexible architectures for biomedical applications

One of the main challenges in neural tissue engineering is the ability to exploit supporting materials for the development of nerve guidance conduits with complex architectures and customizable geometry, while matching the biomechanical properties of native tissues. It is proven that conductive materials can be sufficient to allow nervous signal to travel, in that matter, once voltage stimulus can induce axonal regrowth, graphene, being an atomically thin nanomaterial with exceptional functional and electrical properties, appears as an alternative to open up possibilities in the field. However, its practical utilization depends on the ability to integrate 2D sheets into rather complex 3D structures of practical dimensions, while controlling structural features at multiple length scales. Starting with the design of a graphene nanoplatelet based ink with precise and optimized rheological properties, this study focuses on developing the scientific and technological capabilities for 3D printing nerve conduits with suitable properties for biological applications. A double network hydrogel of functionalized pluronic F127 and sodium alginate was used as matrix for graphene nanoplatelets to produce a 3D printed composite (F127 DA/Alg/xGnP) of flexible and conductive properties. In addition, cytotoxicity assays reveal cells adhesion and vitality increasing in materials with up to 10 wt% of GnP content.