Tunable stiffness of graphene oxide/polyacrylamide composite scaffolds regulates cytoskeleton assembly.

The stiffness of the extracellular matrix (ECM) not only provides mechanical resistance to support the cellular shape, but also plays significant roles in many cell functions. However, it's difficult to utilize traditional substrate materials to investigate cell behaviors under physical microenvironments due to their unphysiological stiffness or intrinsic secondary effects. Herein, a stiffness-tunable graphene oxide/polyacrylamide composite scaffold was fabricated to investigate the effect of substrate stiffness on cytoskeleton assembly and specific gene expression during cell growth. In the composite structure, the polyacrylamide (PAAm) hydrogel plays an exceptional role in controlling the substrate stiffness; in contrast, graphene oxide (GO) sheets not only provide permissive surfaces for cell adhesion and growth, but also effectively eliminate the secondary effects of the PAAm hydrogel. It's found that substrate stiffness could affect cell morphology and cytoskeleton assembly via specific genetic pathways. Therefore, the composite structure can be considered an attractive candidate as a scaffold and provides potential to elucidate the disease association of ECMs.