Meanwhile, the vigorous metabolism of most brain tumors and the increase in iron demand leads to the elevated expression of the transferrin receptor on the surface of the tumor cells, which is about 100 times that of the normal neuron, so that, by using the transferrin receptor-ligand binding effect, dual brain-targeted delivery can be realized (Kawabata, 2019; Sahtoe et al., 2021). The gene discussed is TFRC; the disease is brain neoplasm.