Fig. 2

Strategies for improving nanomedicine delivery passing through BBB. a Schematic representation of three major mechanisms to enhance BBB penetration: i transporter-mediated transcytosis, ii receptor-mediated transcytosis (RMT), and iii absorption. Reproduced with permission [5]. Copyright 2006, Nature Publishing Group. b Nanomedicines functionalized with transporter-targeting molecules. Glucose transporter-targeting 2-deoxy-d-glucose decoration increased the deposition of nanoparticles in the brain passing through BBB while fluorescent dye, DiR, encapsulation allowed an efficient imaging. Reproduced with permission [115]. Copyright 2006, ELSEVIER. c Absorption-enhancing nanoparticles. The magnetic nanoparticles decorated with albumin can be delivered to the brain region from the vein through the enhanced absorption pathway. Reproduced with permission [109]. Copyright 2016, Nature Publishing Group. d Ligand-targeted nanoliposomes promoting receptor-mediated endocytosis. In vivo multiphoton images of brains receiving i non-targeted liposomes or ii transferrin-functionalized liposomes. The targeted liposomes were able to pass the BBB and accumulated in the brain regions via RMT pathway while non-targeted liposomes were concentrated in the vessel regions. Scale bar represents 25 μm. Reproduced with permission [122]. Copyright 2018, Nature Publishing Group