Method to impart electro- and biofunctionality to neural scaffolds using graphene-polyelectrolyte multilayers

Electroactive scaffolds that are passively conductive and able to transmit applied electrical stimuli are of increasing importance for neural tissue engineering. Here, we report a process of rendering both 2D and 3D polymer scaffolds electrically conducting, while also enhancing neuron attachment. Graphene-heparin/poly-l-lysine polyelectrolytes were assembled via layer-by-layer (LbL) deposition onto 2D surfaces and 3D electrospun nanofibers. The employed LbL coating technique in this work enables the electro- and biofunctionalization of complex 3D scaffold structures. LbL assembly was characterized by a steady mass increase during the in situ deposition process in 2D, with regular step changes in hydrophobicity. Uniform coverage of the graphene/polyelectrolyte coatings was also achieved on nanofibers, with hydrodynamic flow and post-thermal annealing playing an important role in controlling sheet resistance of 2D surfaces and nanofibers. Cell culture experiments showed that both 2D and 3D graphene-PEMs supported neuron cell adhesion and neurite outgrowth, with no appreciable cell death. This electroactive scaffold modification may therefore assist in neuronal regeneration, for creating functional and biocompatible polymer scaffolds for electrical entrainment or biosensing applications.