 The blood-brain barrier, BBB, is a physical barrier that prevents certain substances from entering the brain. This can make it difficult to treat diseases in the brain, as many medications cannot cross the BBB. Material science and nanotechnology have provided new tools for targeting drugs to the brain, such as passive transitosis, intranasal administration, ligand conjugation, membrane coating, stimuli, triggered BBB disruption, and more. These techniques offer potential solutions for delivering drugs to the brain, while minimizing side effects. This article was authored by D.I. Wu, Ji Chen, Xiao Jie Chen, and others.