Noninvasive nanoparticle strategies for brain tumor targeting

The blood-brain barrier (BBB) maintains the integrity and homeostasis of the central nervous system (CNS) yet represents an intimidating hurdle for efficient drug delivery to brain tumors. This up-to-date review summarizes strategies that have been employed to cross the BBB with a focus on non-invasive nanoparticles that could pass the BBB after systemic administration. Recent advances in liposomes, polymeric nanoparticles, micelles, and inorganic nanoparticles are scrutinized mechanistically with an emphasis on design principles. As highlighted in this review, effective drug delivery to brain tumors may be achieved by rationally engineering nanoparticles to possess appropriate sizes, surface properties, and ligands.