The effect of the morphological chirality of inorganic TiO₂ nanofibers on peptide assembly and cellular behaviors was investigated. Model peptide insulin maintains its native structure and served as a growth factor for promoting proliferation and differentiation of PC12 cells on the surface of right-handed TiO₂. In contrast, insulin forms amyloid fibrils and loses its bioactivity on the left-handed TiO₂.