Drug delivery to the brain using colloidal carriers

Many neurodegenerative diseases, cancer, and infections of the brain become more prevalent as populations become older. Despite major advances in neuroscience, the blood-brain barrier (BBB) ensures that many potential therapeutics cannot reach the central nervous system (CNS). The BBB is formed by the complex tight junctions between the endothelial cells of the brain capillaries and their low endocytic activity. It results in the capillary wall that behaves as a continuous lipid bilayer and prevents the passage of polar substances. Drug delivery to the brain has remained one of the most vexing problems in translational neuroscience research, because of the difficulties posed by the BBB. Several strategies for delivering drugs to the CNS have been developed. This review rationalizes the strategies to target drugs to the brain by using different colloids.