ABSTRACT
The blood-brain barrier (BBB), formed by brain capillary endothelial cells (BCECs) connected through tight junctions, provides excellent barrier functionalities, preventing penetration of blood-circulating compounds into the brain parenchyma. Excellent restrictiveness of BBB controls the entrance of drugs into the brain discriminately; hence, brain drug delivery and targeting (BDDT) needs to be advanced to circumvent the tight barrier restrictiveness of BCECs. The transport machineries of BCECs can be utilized for efficient delivery of drugs into brain. Once inside, the drugs need to be accumulated in the target site through targeting diseased cells. Of the molecular machineries, carrier- and receptor-mediated transporters provide great possibility for drug transportation into the brain. Modified drug-delivery systems (DDSs) 38appear to be success paradigms for BDDT. Chemically modified drugs with inherent properties (e.g., drug-polymer nanoconjugates, prodrugs, drug-ligand conjugates) have been successfully used. Further, surface-modified/ functionalized nanosystems (NSs) encapsulated/loaded with designated drug molecules that are categorized into organic (e.g., polymer and lipid) and inorganic (e.g., gold, iron oxide) nanoparticles have also been utilized. Of these, dual-targeting NSs and multifunctional nanomedicines and theranos-tics have undergone for translation into clinical applications. The main aim of this chapter is to discuss the importance of BBB on BDDT and advanced drug delivery systems (DDSs) used for targeted therapy of brain diseases.
