Apart from passive targeting by blood transportation and structural advantages, active targeting by surface modification is also used widely to optimize selectivity, such as epidermal growth factor receptor (EGFR)-ligand and vascular endothelial growth factor (VEGF)-ligand for tumor targeting, and transferrin ligand and sphingomyelin for BBB penetration [42, 44, 45]. Here, EGFR is linked to neoplasm.