Maintaining cytocompatibility of biopolymers through a graphene layer for electrical stimulation of nerve cells
Here, the utility of large-area graphene as a flexible, biocompatible electrode to stimulate cell growth is demonstrated. Chemical vapor deposition allows the production of highly crystalline, single, double, or few-layered graphene on copper substrates. The subsequent transfer to a biopolymer support, such as polylactic acid (PLA) or polylactic-co-glycolic acid (PLGA) copolymers, provides a unique electrode structure retaining the flexibility and surface properties of the underlying materials with a conductive graphene layer sufficient to enable electrical communication with excitable cells. The growth and compatibility of PC-12 cells on these graphene-biopolymer (GPB) electrodes is influenced more by the underlying polymer than the presence of graphene, demonstrating that the characteristics influencing biocompatibility have been retained after graphene modification. Differentiation of these cells into neural phenotypes is enhanced using electrical stimulation through the graphene conductive layer, confirming that the conductivity of graphene is sufficient to electrically communicate with cells grown on the surface. The process described herein demonstrates that non-conducting, flexible biopolymer surfaces can be easily coated with graphene without changing the biocompatibility of the materials. This could be used to create electrodes from non-conducting materials with optimized cell compatibility with graphene providing electrical properties suitable for stimulation of cells without greatly changing the surface properties.