Abstract: The blood-brain barrier (BBB) is a special structure in the central nervous system (CNS), whose delicate properties can protect the brain from the attack by harmful large molecules and organisms within blood circulation. However, the very barrier also prevents the brain-targeted drugs from taking effects, posing great challenge to the treatment of neurodegenerative diseases, glioma and other brain diseases. With the development of nanotechnology, more and more nanoparticles (NPs) have been developed as drug carriers, which can facilitate the drug with various mechanisms to get across the BBB. This article starts with introduction of the BBB, explaining the complexity of BBB structure and its unique features to form barriers, so that we can understand the difficulty in transporting drug into the BBB and the potential methods of targeting and permeate the barrier. Next, we focus on three main types of NPs that have been applied in the brain-targeted drug delivery system: polymeric-based NPs; biomimetic-based NPs and inorganic-based NPs. Furthermore, we deal with the specific NPs drug delivery strategies, which include absorption-mediated, carrier-mediated and receptor-mediated transcytosis. At the end of the article, we talk about the leading trend and future development of the brain-targeted nanoparticle drug delivery systems.

Key words: blood-brain barrier, nanoparticles, brain-targeted, drug delivery systems