Degradable biophotonic scaffolds of mesoporous graphene for regenerating neural pathways

Mesoporous graphene frameworks (MGFs) were synthesized as p-type semiconductors with a nonzero band gap of ~1 eV and used as 3D photo-sensitive scaffolds for effective differentiation of human neural stem cells (hNSCs) into 3D-neural networks, under near-infrared (NIR) laser stimulation. The fabrication process involved the chemical vapor deposition (CVD) of 3D graphene frameworks (GFs) on Ni foams, followed by the removal of the Ni templates. Subsequently, TiO2 nanoparticles were employed to induce localized photocatalytic degradation of the CVD-grown sheets of the 3D-GF to obtain the 3D-MGFs. The biocompatibility of the graphene frameworks was evaluated by assessing the proliferation and differentiation of hNSCs. Under NIR stimulation, the 3D-MGF scaffolds exhibited more proliferation of hNSCs and higher cell differentiation into neurons (rather than glia) as compared to the 3D-GF ones. The better performance of the 3D-MGFs is attributable to the photocatalytic activity of the scaffolds induced by the injection of low-energy (<0.5eV) photoelectrons from the scaffold into the cells. The MGFs also exhibited a degradable property under photocatalytic reactions induced by the NIR laser irradiation in the cell culture media. These results suggest the potential for in-vivo regeneration of neural networks on biocompatible as well as biodegradable scaffolds through NIR-laser therapy, contributing to advancements in emerging nanomedicine.