Controlling ligand surface density optimizes nanoparticle binding to ICAM-1

During infection, pathogens utilize surface receptors to gain entry into intracellu- lar compartments. Multiple receptor-ligand interactions that lead to pathogen internalization have been identified and the importance of multivalent ligand binding as a means to facil- itate internalization has emerged. The effect of ligand density, however, is less well known. In this study, ligand density was examined using poly(DL-lactic-co-glycolic acid) nanoparticles (PLGA NPs). A cyclic peptide, cLABL, was used as a targeting moiety, as it is a known lig- and for intercellular cell adhesion molecule-1 (ICAM-1). To modulate the number of reactive sites on the surface of PLGA NPs, modified Pluronic R with carboxyl groups and Pluronic R