Background: The blood-brain barrier restricts drug penetration to the central nervous system. Targeted
nanocarriers are new potential tools to increase the brain entry of drugs. Ligands of endogenous transporters of
the blood-brain barrier can be used as targeting vectors for brain delivery of nanoparticles.
Objective: We tested biotin-labeled solid nanoparticles for the first time and compared to biotinylated glutathione-
labeled nanoparticles in brain endothelial cells.
Method: Neutravidin coated fluorescent polystyrene nanoparticles were derivatized with biotin and biotinylated
glutathione. As a human in vitro blood-brain barrier model hCMEC/D3 brain endothelial cells were used. Cell
viability by MTT test, uptake and transfer of the nanoparticles across the endothelial monolayers were measured.
The uptake of the nanoparticles was visualized by confocal microscopy.
Results: The tested nanoparticles caused no change in cell viability. The uptake of biotin- and glutathione-labeled
nanoparticles by brain endothelial cells was time-dependent and significantly higher compared to non-labeled
nanoparticles. The penetration of the glutathione-labeled nanoparticles across the endothelial monolayer was
higher than the biotin-targeted ones. Biotin- and glutathione-targeted nanoparticles were visualized in
hCMEC/D3 cells. We verified that hCMEC/D3 express mRNA for sodium-dependent multivitamin transporter
(SMVT/SLC5A6) responsible for the blood-brain barrier transport of biotin.
Conclusion: Biotin as a ligand increased the uptake and the transfer of nanoparticles across brain endothelial
cells. Biotinylated glutathione could further increase nanoparticle permeability through endothelial monolayers
supporting its use as a brain targeting vector.