(229ah) Differentiation of Neural Stem Cells into Neurons By Visible Light‐ Induced Electrical Stimulation

Neural tissue engineering aims to regenerate irreversibly damaged neural systems (either peripheral or central nervous systems) by differentiation of neural stem cells into neurons on three dimensional scaffolds by providing various chemical and physical cues. One physical cue that has received much attention is electrical stimulation by an external electric potential on conducting substrates such as graphene. One potentially useful method of achieving electrical stimulation of neural stem cells is by free electron generation on the surface of titanium oxide (TiO2) nanoparticles by light irradiation. However, the band gap of TiO₂ nanoparticles is in the UV range which can be harmful to cells and has many limitations in clinical applications. The goal of this research is to develop a novel method to achieve visible light-triggered differentiation of human neural stem cells (hNSCs) into neurons. We have discovered that TiO₂ grown on polydopamine (PDA) coated substrates exhibits an absorption peak in the visible light range. The surface chemistry was confirmed by various surface characterization methods including XPS, SEM and FT-IR. Using this substrate, we investigated the effect of YIGSR peptide on hNSC adhesion, surface free electron generation on TiO2 by visible light irradiation, and preferential differentiation of hNSCs into neurons. The results from this research open up a new possibility for implantable neural tissue engineering scaffolds that can be activated by light irradiation.