Nanoparticle technology for drug delivery across the blood-brain barrier

Nanoparticles (NP) are solid colloidal particles ranging in size from 1 to 1000 nm that are utilized as drug delivery agents. The use of NPs to deliver drugs to the brain across the blood-brain barrier (BBB) may provide a significant advantage to current strategies. The primary advantage of NP carrier technology is that NPs mask the blood-brain barrier limiting characteristics of the therapeutic drug molecule. Furthermore, this system may slow drug release in the brain, decreasing peripheral toxicity. This review evaluates previous strategies of brain drug delivery, discusses NP transport across the BBB, and describes primary methods of NP preparation and characterization. Further, influencing manufacturing factors (type of polymers and surfactants, NP size, and the drug molecule) are detailed in relation to movement of the drug delivery agent across the BBB. Currently, reports evaluating NPs for brain delivery have studied anesthetic and chemotherapeutic agents. These studies are reviewed for efficacy and mechanisms of transport. Physiological factors such as phagocytic activity of the reticuloendothelial system and protein opsonization may limit the amount of brain delivered drug and methods to avoid these issues are also discussed. NP technology appears to have significant promise in delivering therapeutic molecules across the BBB.