Mediate neurite outgrowth of PC-12 cells using polypyrrole-assisted laser-induced graphene flexible composite electrodes combined with electrical stimulation

Although electrical stimulation (ES) has been proved to be an effective strategy in promoting the regeneration and repair of injured peripheral nerve tissue, it is still a big challenge to encounter the risk of inflammation and infection when the conductive biological platform directly contacted with the damaged tissue. Therefore, it is a very promising solution to develop non-invasive flexible electrodes’ bio-scaffolds for clinical treatment of nerve tissue regeneration combined with ES. With such purpose, the flexible composite electrodes by depositing polypyrrole on laser-induced graphene (LIG) have been developed. The proliferation and differentiation of PC-12 cells incubated on the prepared composite electrodes combined with an ES of 400 mV/cm at different times have also been investigated. The results showed that the fabricated composite electrodes exhibited excellent conductivity and wettability. Moreover, the essence of ES was to induce a field effect, namely, the cell proliferation was independent of the conductivity of the composite electrodes. In addition, we observed that ES could significantly enhance proliferation and differentiation of PC-12 cells. With the prolongation of ES time, the increasing trend finally stabilized. Importantly, the cell growth through MTT value was 1.37 when ES time was 4 h, and the increment was the largest, reaching 0.3, compared with that of 2 h. Furthermore, the cell differentiation showed that the neurite outgrowth length at 8 h of ES was the broadest distribution (the half-width ca 33.83 μm). And the average neurite length reached 68.39 μm after 8 h of ES, which increased by 16.26 μm compared with that of 4 h. This work inspires the design and construction of a practical conductive platform, and provided a new theoretical basis and data support for clinical therapy in nerve tissue engineering combined with ES.