Transport of Nanoparticles Across Blood–Brain Barrier

The blood–brain barrier (BBB) is the most important structure in defense of the central nervous system (CNS) from potential toxicities of the systemic circulation. Nanoparticles offer an ideal method of transport across this barrier. A clear understanding of BBB structure and function must be attained prior to considering nanoparticle strategies. The BBB is not a static wall but, rather, an adaptable filter able to adjust to varying circumstances. It plays physical, metabolic, and immunologic roles, allowing a separate and distinct extracellular fluid compartment. Uptake of nanoparticles can occur via sensory nerve endings within airway epithelia or via the olfactory bulb, followed by axonal translocation to the CNS. Liposomes, micelles, and dendrimers are all structures that have been used as vehicles for crossing the BBB. While they have applications as drug delivery and imaging modalities, most publications about them have focused on drug delivery. Nanotechnological approaches to brain tumor therapy and imaging have limitations. The extensive brain microvascular network makes targeted delivery across the BBB an ideal route for global brain drug delivery. Nanoparticles offer an effective vehicle for crossing this highly impermeable barrier. While challenges remain concerning nanoparticle safety for patients and health care providers, and nanoparticle dispersion and delivery once it crosses the BBB, nanotechnology holds great promise for providing novel, more effective therapies for neuropathologies and more sensitive and specific imaging modalities.