Provided herein are peptide amphiphiles (PAs) and supramolecular PA nanostructures that mimic brain derived neurotrophic factor (BDNF), a growth factor that induces neuronal survival, maturation, and increased electrical activity. In particular, injectable biomaterials comprising BDNF mimetic PAs are provided, as well as methods of using BDNF mimetic PAs for the treatment or prevention of neurological injuries, diseases, and disorders.