To test the hypothesis that coating of superparamagnetic iron oxide nanoparticles (IONPs) with platelet-endothelial cell adhesion molecule (PECAM)-1 antibody increases nanoparticle association with the blood-brain barrier (BBB) and its biodistribution in vitro and in vivo.Anti-PECAM-1-coated IONPs and non-specific IgG-coated IONPs were prepared and characterized in house.The binding affinity of these nanoparticles was investigated using human cortical microvascular endothelial cells (hCMEC/D3).Flux assays were performed using a hCMEC/D3 in vitro BBB model.To test their immunospecificity index and biodistribution,nanoparticles were given to Sprague Dawley rats by carotid artery infusion.