Shuttle-Mediated Nanoparticle Delivery to the Blood–Brain Barrier

Many therapeutic drugs are excluded fromentering the brain due to their lack of transport through the blood–brain barrier (BBB). The development of new strategies for enhancing drug delivery to the brain is of great importance in diagnostics and therapeutics of central nervous diseases. To overcome this problem, a viral fusion peptide (gH625) derived fromthe glycoprotein gH of Herpes simplex type 1 is developed, which possesses several advantages including high cell translocation potency, absence of toxicity of the peptide itself, and the feasibility as an efficient carrier for delivering therapeutics. Therefore, it is hypothesized that brain delivery of nanoparticles conjugated with gH625 should be efficiently enhanced. The surface of fluorescent aminated polystyrene nanoparticles (NPs) is functionalized with gH625 via a covalent binding procedure, and theNP uptakemechanismand permeation across in vitro BBBmodels are studied. At early incubation times, the uptake of NPs with gH625 by brain endothelial cells is greater than that of the NPs without the peptide, and their intracellularmotion ismainly characterized by a randomwalk behavior.Most importantly, gH625 peptide decreases NP intracellular accumulation as large aggregates and enhances the NP BBB crossing. In summary, these results establish that surface functionalization with gH625 may change NP fate by providing a good strategy for the design of promising carriers to deliver drugs across the BBB for the treatment of brain diseases.