The 25% transport increase achieved with BB4 after 2 h is comparable to the enhancements previously reported with other well-known brain shuttle peptides on other nanoparticulate systems in similar BBB models. For instance, THR retro-enantio peptide enhanced the transport of poly(methylmetacrylate) nanoparticles by 25% after 4h, and peptide 22 provided a 25%