Effects of graphene on the structure, properties, electro-response behaviors of GO/PAA composite hydrogels and influence of electro-mechanical coupling on BMSC differentiation

Electro-responsive Graphene oxide-poly(acrylic acid) (GO-PAA) nanocomposite hydrogels with different concentrations of GO were successfully fabricated via in situ polymerization. The covalently crosslinked PAA network is intertwined with GO sheets by the bridging of hydrogen-bond interactions thus resulting in an integrated and stable hydrogel network. The swelling, mechanical and conductivity properties of the hydrogel are impacted as a result. The influences of different factors on the electro-response behavior of the hydrogels were deeply explored. Because of electrostatic double layer of the GO, the response properties of hydrogels in different voltage, pH, and ionic strength improved significantly. Meanwhile, with the addition of GO, the response performance of hydrogel in biological applications was greatly expanded. Furthermore, GO-PAA hydrogel shows a good compatibility with bone marrow-derived mesenchymal stem cells (BMSCs). The electro-mechanical coupling of the hydrogel can change the morphology of the adhesive cells, and regulate the cytoskeleton of the cell under the condition of electrical stimulation, which can further promote the differentiation of neural stem cells. This electro-responsive hydrogel could be widely used in many fields of biomedical application such as artificial muscle and tissue engineering scaffold.