Soft Graphene Nanofibers Designed for the Acceleration of Nerve Growth and Development

Understanding in the cells responses to programmed electrical signals is a vital tool for the study of the various biological research fields from bioelectronics to regenerative medicine, especially for the nerve engineering. In this study, a novel soft graphene nanofibers was successfully prepared by controlling the assembly of graphene oxide sheets on the surface of electrospun polymer nanofibers, and followed by chemical reduction with hydriodic acid. The graphene nanofibers have ultrathin graphene shells that wrapped the entire surface of the polymer nanofiber, which led to a flexible feature and recoverable electrical conductivity, and physicochemical stability in aqueous solutions with pH values from 2.0 to 11.0. By using the graphene nanofibers for cellular electrical stimulation, a sustained and irreversible change on the electron charge density and the location of the opened Ca²⁺ channel in the cell membrane was achieved, which avoided the common inhibitory effect of the long-term electrical stimulation on the replenishment of Ca²⁺ store, and resulted in a fast and sustainable promotion on the neurons growth and development. The speed of the neurites elongation and maturation of these neurons was almost two times than that of the neurons on the tissue culture plates and graphene film with or without electrical stimulation. We envision that the graphene nanofibers maybe can serve asa powerful tool for developing future therapies for nerve-related disease and injuries in central and peripheral nervous system. In addition, the successful formation of graphene shells in the complex 3D nanofibers extended the superior properties of graphene from traditional 2D nanometer scales to 3D micrometer scales by controlled assembly of graphene oxide sheets in 3D architectural geometry. We expect that this novel preparation technique will open a new way to adapt the graphene macroscopic real-world applications, not only to biomedicine, but also to chemical, electronic, energy, and environmental applications.