No abstract

The blood-brain barrier is one of the most complicated barrier to pass for therapeutic drugs. Because of the structure of the blood-brain barrier, only a few small molecules with appropriate lipophilicity, molecular weight, and charge can penetrate through the blood-brain barrier and pass in the central nervous system. Because of this unique property, blood-brain barrier is still a major problem for the treatment of central nervous system diseases. In the last decades, many strategies to overcome this barrier have been investigated. Compared to other drug delivery strategies, due to the reduced side effects and no requirement for surgical operations, brain targeted nanoparticle is one the most promising and popular strategy used do deliver drugs to the brain. Many in vitro and in vivo preclinical studies have been conducted to determine optimum brain targeted nanoparticles. These studies were reported that characteristics of nanoparticles such as particle size, zeta potential, and targeting ligand are critical to achieving the goals. In this review, first of all, the structure of the blood-brain barrier and possible causes of blood-brain barrier disruption were summarized. Later, previous strategies of brain targeted drug delivery and characteristic prosperities for optimized brain-targeted nanoparticles were evaluated. Moreover, different strategies, such as focus ultrasound, which can increase the effectiveness of nanoparticular system applications, are mentioned.