Nanomedicine for the Brain and the Eye: Disease Management in Poorly Accessible Compartments of the Body

The advent of nanodrugs allows newer strategies to treat poorly accessible lesions, such as those affecting the central nervous system (CNS) or the posterior pole of the eye. These compartments of the body are protected by biological barriers. Their selectivity was first described around 1930, and it was finally stated that hydrophobicity and low molecular weight are requested features of putative drugs for the CNS. Four decades later, techniques for assembling lipids in liposomes were developed. Liposomes interact with biological membranes and carry molecules into the cytoplasm. The partially successful attempt of exploiting liposomes as carriers of drugs to treat brain tumors followed. It was soon clarified that, in neurology, only nanoliposomes retained both biocompatibility and efficacy as drug carriers and adjuvants These experimental evidences together with the bloom of nanotechnology have stimulated researches on new nanomaterials for the diseases of the CNS. Nanotechnology may also target the retina, another site protected by a biological barrier named the blood–retina barrier (BRB).